Momus Design Cnc Router Manual Version 2.1

MomusDesignBENCHTOP CNC ROUTER PLANS

Version 2.1© copyright 2013All rights reserved

release date: March 30, 2013

www.momuscnc.com

v.2.1

page

introduction

machine specifications

design goals

CNC basics

CAD/CAM workflow

exploded views

design alterations

metal parts fabrication

metal parts assembly

wood parts fabrication

wood parts assembly

electronics installation

cover installation

machine alignment

drawing sheets

169suppliers

electronics

enclosure

epoxy bed levelling

spoilboard

preface

bill of materials

structural design

parts list & schedules

168166158155151147145142

138117

140

10493873930292721161513080706050403

Xylotex installation

Gecko G540 installation

limit switches

Mach3 setup

first use

171ADDENDUM: Z axis thrust bearing

02table of contents

The purchaser of this document has express permissionfrom the author to print a hardcopy for personal useonly.This document may not be resold, distributed, or usedfor commercial gain. Commercial sale of componentsor assemblies derived from the information herein isforbidden without prior licensing agreement withMomus Design.

IF THIS DOCUMENT HAS BEEN PURCHASED FROM ANYSELLER OTHER THAN MOMUS CNC, IT HAS BEEN ANUNAUTHORIZED AND ILLEGAL SALE. Please report anysuch activity to Momus CNC.

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03preface

Preface to the 2nd edition

Welcome to the second edition of the Momus DesignCNC router plans. The machine described in thesepages is an evolution and refinement of an earlierdesign, with numerous and significant changesthroughout. The original machine was designed andconstructed in 2008‐2009, with the plans debuting inthe summer of 2010.

After several years of using the machine, and followingthe progress of others who were constructing their owncopies from the plans, it became apparent that therewere many areas that could be improved. By thesummer of 2011 it was felt that there were enoughdesired changes to warrant a full re‐design andrefinement of the original concept.

Many of the design improvements represented in thissecond edition would not have come about without theinput and feedback of all those builders whoconstructed the first version of the machine. Especiallysignificant was the communication between buildersand myself that was made possible by the formation ofa dedicated sub‐forum on CNCzone.com(http://www.cnczone.com/forums/momus_design_cnc_plans/). The existence of this platform has become andintegral and important aspect of both this design andthe plans progressing forward. Please consider this asa welcome invitation to become a part of thiscommunity of builders and observers.

Bob Pavlik‐2012

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04introduction

Introduction

The machine plans contained in this book perhapsbear one significant difference from many others thatare available. The difference is that these plans werenot put together with the goal of selling plans. Theyare the by‐product of building a machine that cameinto existence because of the need for a functionaltool.

The design and fabrication of this machine was due toa specific need, primarily the building of models forarchitectural research, that focused on digital designprocesses and construction automation. The inherentnature of this research required the use of CNCmachinery. Despite having access to large format CNCequipment, the flexibility of having a home‐workshopbased tool seemed to be greatly advantageous.

The design of this machine began as many otherssurely do: by studying existing solutions with theintent of creating a copy of the best currently available.Unfortunately, none of the existing home‐built small‐format CNC routers seemed suited to my particularneeds and constraints. With a small workshop spaceavailable, limited equipment with which to build, theneed to keep dust and noise contained, and a verymeager budget, the existing options were quite limited.

So began the journey of designing and constructing myown machine, a process which ended up consumingseveral years. The resulting machine has far exceededmy initial expectations. The machine has performedsuperbly, proving capable of milling materials nottypically handled by low cost DIY machines (such asaluminum,) and having accuracy that far surpassedoriginal design goals.

Disclaimer:The author of this design is not a professional engineer. Thismanual outlines the construction of a hobbyist machine, designedand built by a hobbyist.

Also note that CNC equipment can be dangerous machinery. Inaddition to the inherent dangers of operating any power tool, doingso remotely, via computer, adds another level of potential danger.Errors in programming machine movement can have catastrophicconsequences.

It is the responsibility of the reader to use the informationpresented in this manual in a manner deemed appropriate topersonal judgment and safety, and use at your own risk.

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05Machine specifications

Machine Specifications:

MACHINE SIZEcutting envelope‐ 16” x 16” x 5.5”overall machine size‐ 32.5”wide x 27.5”deep x 26” tall.

Exact usable Z axis travel will depend on exact configurationof router mount, length of router bit, and thickness ofspoilboard beneath the work piece.

MACHINE CONSTRUCTION MATERIALS

Machine base: PlywoodMechanical parts: Aluminum and steel.

The machine is built entirely from standard stock materialsizes of plywood, aluminum and steel. The stock materialthickness is used for all critical dimensions.

Materials were chosen for this design in order to give thehighest possible machine rigidity for the cost. No MDF(medium density fiberboard) is used in the construction ofthe machine, as it is too flexible to result in a machine ofadequate stiffness.

DIMENSIONINGPlans are dimensioned in Imperial measure. They areNOT currently available in metric.

While the plans are not available in metric, numerousmachines have been constructed in countries that usemetric measure. This can be done either by adaptingthe plans for locally available metric sizes ofmaterials, or by sourcing materials from the US (seelist of suppliers at the end of the plans.)

DRIVE METHODX and Y‐ belt driveZ‐ precision acme leadscrew with anti‐backlash nut

Belt drive can use either open‐ended belting or a closedbelt, depending on availability. Z‐axis anti‐backlash nut isa commercially available product.

LINEAR MOTIONAll axes are controlled by standard ABEC7 bearings ridingon rectangular cold rolled steel rails.

ADJUSTABILITY AND ALIGNMENTAll bearings are provided with a micro‐adjustable setscrewfor precise and easy adjustment.

The design of the machine is based around a step by stepalignment procedure, that allows for highly accurate setupwith very simple tools.

SPINDLEThe machine is intended to use a trim router, such as theBosch Colt, or Ridgid R2400/2401.

MACHINE SPEEDJogging speeds of over 500 inches per minute.

STEPPER MOTORSNEMA23 frame size.Minimum recommended size‐ 275 oz./in.

RESOLUTIONAt 1/10 microstepping:X and Y axes‐ .001”Z axis‐ .0000625”Note that electronic resolution is not an indicator of theaccuracy of the machine. However, it is a potentialindicator of the speed of the machine. The finer theresolution, the slower the machine.

MATERIALS THAT CAN BE CUTWoodPlasticsFoamAluminumBrassCircuit Boards

Note that although the machine is capable of cuttingaluminum, this machine is designed and intendedprimarily as a wood router. Spindle speeds of trimrouters may limit the type of work that can beaccomplished in materials other than wood.

ACCURACYMechanical accuracy: +/‐ .005”Precision (repeatability): +/‐ .001”

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06design goals

Machine Design goals

When this machine was designed, a list of goals and criteria were established at the very beginning of the designprocess. The overall goal was to create an inexpensive machine that could be fabricated in a home shop and performlike a machine costing many times more.

Cost:The machine needed to be as inexpensive as possible, while meeting as many other goals. Target build budgetwas $400, excluding electronics.

Tools:Construction had to be possible with minimal tools and equipment. It had to be constructable with basic toolsthat would not have a high level of accuracy in themselves. This would require creative build techniques tofabricate a machine that was more accurate than the tools used to build it.

Accuracy:It needed to be able to cut to a tolerance of about +/‐.005". Higher accuracy wasn't deemed necessary as themachine was primarily intended to cut wood, which is not a material with high dimensional stability. However,a high enough accuracy was required to allow machining of mating parts that would be assembled, whichrequires more accuracy than simply carving or engraving a single piece.

Enclosed:Due to where the machine would be used, it was necessary to have a full enclosure to contain dust and sound.

Speed: Cutting speed needed to be considerably higher than most other inexpensive DIY machines, which often onlymoved at 20‐30 inches per minute. To facilitate running programs that contained tens of thousands of lines ofcode, a target speed of 150 ipm was set.

Alignment:Many existing home‐built designs had no simple way of attaining accurate machine alignment. An easyalignment procedure was considered integral to a successful to a design.

Bind free:As many existing designs had no way of being accurately aligned, they also often suffered from binding. Linearmotion components that could not be brought into being exactly parallel or in‐plane would cause the machine tobind during travel along its axes. This binding could cause lost steps in the drive motors, potentially ruining awork piece.

Self‐contained:All wiring and electronics should be organized into a single unit, rather than having external components.

Compact:To allow for easy use of the machine at different locations, it must require little or no disassembly/reassembly fortravel.

Attractive:The machine must be attractive and look more like a commercial product than something that was cobbledtogether.

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07CNC basics

Desktop Manufacturing

What was once a technology that existed strictlywithin industry, CNC (Computer Numeric Control)equipment has increasingly found widespread use inthe home workshop. At its most basic, CNC is amethod of using a numerical code to control amachine. Nearly any type of machine orconfiguration can be controlled this way. If it has arange of movement, whether linear or rotary, it canbe controlled by a numerical code that instructsthose movements. Therefore, CNC can be used on awide spectrum of equipment, such as millingmachines, lathes, plasma cutters, water jets, hot wirefoam cutters, wire EDM, etc. Or, as is the case withthese plans, a 3‐axis wood router.

In the early development of CNC, the numbers thatwere used to control a machine were hand‐codedand punched into a paper roll that was fed through amechanical reader. The punched holes equated todiscrete movement steps. While programmingsimple movements, such as straight lines, was easilyaccomplished, curved or free‐form geometry wasmuch more difficult to achieve. With these complexshapes, the smaller the distance between the motionsteps, the smoother the results, necessitating thecalculation of thousands of movement points. Withthe advent of the computer came the ability togenerate much more complex numerical code,resulting in very smooth machine motions.

More recently there has been a tremendous growthin Do‐It‐Yourself (DIY) home‐built CNC equipment. Itis now a relatively straightforward process togenerate the code (“G‐Code”) to control a CNCmachine tool on a home PC, and output the signalthrough a parallel port or USB port to motion controlmotors. Depending on how complex andsophisticated the geometry of the parts beingmanufactured, this can even be accomplished withfree software.

The potential implications for this revolution in “desktopmanufacturing” are huge. Transferring the manufactureof extremely complex parts from costly industrialsettings, which was the only option in the recent past, toa low‐cost home shop opens up a world of possibilities.Many of the machines that have been constructed fromthe plans in this manual have found use in small home‐based manufacturing businesses.

However, having the ability to easily have thesemanufacturing capacities available raises questions ofappropriate use of technology. If a part can adequatelybe made by more traditional hand crafted methods, itmay be an inefficient use of time and resources to use acomputer controlled machine. In addition to the initialtime invested in machine construction, the fabrication ofa part can require significant time spent at the computer.Even a simple part requires drawing or 3d modeling it,deciding on a machining strategy, generating toolpathsand G‐code from the drawing, and setting up the stock tobe cut on the machine.

The advantages comes in using the equipment forpurposes that cannot be achieved easily by other means.CNC lends itself to jobs requiring high levels of accuracy,consistency between repetitive parts, and cuttingcomplex geometries. These advantages are significant,and potentially transformative, for both hobby andbusiness use.

DESIGN (CAD)

TOOLPATHS (CAM)

MACHINE CONTROL

Design parts in software such asAutoCad, Rhino, Solidworks,TurboCad, etc...

Generate movement of thecutting tool in software such as:MasterCam, RhinoCam,BobCad/Cam, etc...

Send cutting tool information tothe machine with software suchas:Mach3, emc2, TurboCNC, etc..

SOFTWARE W

ORKFLOW

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08CAD/CAM workflow

CAD/CAM Workflow

Designing parts to millParts that ultimately will be cut with the machine needto originate somewhere, and that typically happenswithin some sort of CAD (Computer Aided Design)software such as AutoCad, Rhino3d, Solidworks,AutoDesk Inventor, TurboCad, or even software such asCorel draw. This software may be either a 2d or 3denvironment. The type of software required will bedriven in large part by the type and geometriccomplexity of the work being designed. Very simpleparts that are being cut from sheet stock can bedesigned in very rudimentary software that merelyallows you to accurately draw two‐dimensional lines andexport that information in an appropriate file format.Cutting parts of this nature is often referred to as 2 ½axis milling, as most of the machine motion happenswithin only 2 axis. The spindle only moves up and downin the Z axis to enter the work at the beginning of thecut and to lift itself clear of the material at the end.Simple parts can be designed in one of the manyfreeware 2d drafting software packages available, aslong as the design can be exported in a file format thatis compatible with other software that will be useddownstream in the workflow (the CAM software).

Creating the geometry for complex three dimensionalsurfaces requires a much more advanced software thanis necessary for simple 2d linework. Software such asRhino3d, Solidworks, or Inventor are powerful 3dmodeling tools designed specifically to manipulatesophisticated topographical geometries. Cutting thesesurfaces is considered full 3d milling, as the Z axis ofthe spindle is moving in careful coordination with the Xand Y axes to result in the desired shape. Thesesurfaces are exported in file formats that preserve theirtopographical data.

ToolpathsThe next step in the CAD/CAM workflow is typically togenerate toolpaths, or the movements of the machinethat are necessary to cut your part. This can happen inCAM (Computer Aided Manufacturing) software such asMastercam, RhinoCam, MeshCam, MadCam, or a rangeof other programs. The following are basic steps thatare often part of the workflow within a CAM softwarepackage.

1. Machine definition.The software needs to know the configuration of themachine itself. While many of the more basic programsare only capable of 3 axis milling, more advancedsoftware can handle more machine axes, or alternateconfigurations of how those axes move.

2. Stock setup.The software needs to know how large your piece ofstock is, so that it can calculate how much materialmight need to be removed from around the final part.This is less important in basic 2 ½ axis milling, where itoften really does not matter how large the stock mightbe, as long as it is sufficiently large to allow clamping tothe machine bed at a safe distance from the cuttingpath. Stock size is much more crucial when doing full 3axis milling, as the increased amount Z axis movementscreates more opportunities for collision between thecutting tool and the stock. So again, this is a situation ofneeding to match the abilities of your software to thetypes of parts that you want to make. Complicatedparts may even need to have additional geometry drawnin the design software, to provide additional cuttingsurfaces to remove material for needed tool clearance.

There are a couple of typical ways to enter stock sizeinformation within CAM software. One is to entercoordinates for the corner points of your stock size.Better CAM software can automatically detect theboundary size of your part and generate a stock sizearound that. In this case, it is often desirable to drawthe uncut block of material in the design software, sothat the CAM software creates the desired material size.

CAD = Computer Aided DesignCAM = Computer Aided Manufacturing

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09CAD/CAM workflow

3. Tool size.The software needs to know the diameter and shape of thecutting tool. Many CAM packages have a library of tools fromwhich you can pick the size and shape of your cutting bit. Inothers you may need to enter this information manually.

4. Cutting speeds and feeds.Depending on numerous factors (the type of material being cut,the type of cutting tool, the rpm speed of the spindle, how muchof the tool is being engaged in the material, and the quality offinish desired), the feedrate must be set for how fast the tool ispushed through the material. On most home‐built machines thespindle speed is set at the router itself, so that does not need tobe controlled through the software. The feedrate must be fastenough that the tool can efficiently eject the cut material awayfrom the cutting area.

There are two methods of determining feed rates. The bestmethod is to do a “chip load” calculation, which takes all of thosefactors above into account. The principle of this calculation isthat it provides for an ideal quantity of material to be removedby the tool's cutting edge each time it moves through thematerial. This quantity is often published by the manufacturerof the cutting tool. This calculation will give a fairly accuratenumber for setting feedrate.

The other method is an empirical process, where experience canprovide an equally good feedrate number, or can aid in finetuning the number that is arrived at by a chip load calculation.Unfortunately, in practice many other home‐built machinesrequire neither method. They typically have a maximum travelspeed that is far below running any danger of going too fast. Sothey can often simply be run at the highest feedrate that themachine will allow. If anything, many home‐built machinesoften have the problem of running so slowly that they can causea poor surface finish, or even damage to the part or cutting tool,because they do not remove material quickly enough to keep thecutting edge cool When cutting wood this can cause burning ofthe material.

5. Toolpaths.The next step is typically to generate the actual paths that thetool will follow. With simple 2 ½ axis cutting this is a very simpleprocess without many factors. Primarily all that matters is thesize of the tool. More complex 3d cuts open up a wider array ofcutting options. Complex parts may require determining alogical cutting strategy, to remove material in a series of stagesthat will result in the best surface finish or require the least time.

Roughing vs. FinishWhen removing large amounts of material quickly, a“roughing” cut is often used. This is a fairly aggressive cutdesigned to remove stock around the final geometry quicklyand efficiently. It may have the tip of the tool engaged deepinto the material, and when multiple parallel passes arerequired it may step over as far as the entire diameter ofthe tool between each pass. The roughing cut will typicallythen be followed by a finish cut which removes a muchsmaller final amount of material, both in depth of cut anddistance of step‐over between passes. There may even be achange of cutting tools between the roughing and finishcuts.

PlungingWhen milling part geometries where the tool can not simplyenter the workpiece from the edge of the stock, such aswhen cutting a pocket, the tool needs to make some type ofdescending cut into the material. The simplest method is tomove the tool straight down into the material, which mayor may not be the most appropriate movement. Manycutting tools are not designed to be plunged straight downinto material in such a way. A tool that can accommodatethis move is referred to as “end‐cutting,” and can cut on itstip as well as its side. When the tool cannot be plunged, thetip will need to be gradually lowered into the stock as it issimultaneously moved in a sideways direction. This iscalled “ramping” into the material. The best CAM programsprovide great control over how the tool can be rampeddown into the material, including straight ramping andhelical moves. It may also be desirable to avoid straightplunge cuts due to material properties. The grain of somewoods may tear under such a tool movement.

Direction of cutAny amount of experience with a hand‐held router willquickly reveal the difference between moving the tool fromleft to right and right to left along the edge of a piece ofmaterial. One direction will be much harder to control.With a hand‐held router you would typically move left toright to maintain the greatest control of the tool. This iscalled conventional milling. If moving in the otherdirection (“climb cutting”) the router bit may grab into thematerial and be pulled in an undesirable direction.However, when controlling the router with a machine thesituation is not so simple. Depending on the circumstances,climb cutting may provide a much finer surface finish.

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10CAD/CAM workflow

6. Simulation.Many CAM programs have a simulation feature which willallow viewing a 3d computer simulation on the computerscreen of the tool cutting the material. This can allowwatching if the tool is moving in desired directions andsequences, and if there are any possible collisionsbetween the machine and the stock. The best CAMprograms will automatically detect these collisions andprovide a warning.

7. Post‐processing.Once all of the above steps have been finalized, and theoperator is content with the toolpaths, the final step is“post‐processing.” This is where the software convertsall of the toolpath information into a format that can beread by other software that will control the movements ofthe machine itself. This is typically some variation of anindustry standard language called “g‐code”, which is asimple text file. G‐code is nothing but a line by line set ofnumerical instructions for the machine to follow. It givestool movement information in absolute coordinates, andmay also provide information such as feedrate andspindle speed, and on more advanced equipment, movessuch as automatic tool changes.

While G‐code is a standard language, unfortunately eachmachine controller software often uses its own variation.The machine control software typically used by the home‐builder runs on a version that is often very close to pure(canonical) g‐code. More specialized machinery, whichhas its own control electronics rather than using a PC forcontrol, often has a correspondingly more specializedversion of g‐code.

Similar to the need for matching the design software tothe type of parts that you want to create, it may takesome necessary care to match CAM software to controlsoftware. Problems may be encountered with findingCAM software that can handle generating toolpaths forcomplex geometry, yet has proper post‐processing abilityfor control software such as Mach 3 or emc2, which aretypical of what is used by the home user. Software thatwill accommodate very complex geometry may only haveposts available for more industrial machine controls. Thismight mean learning enough g‐code to be able tomanually edit and alter post‐processed code for use in PCbased control software.

Machine Control softwareMach 3, emc2, TurboCNCThis software takes the code that was generated by theCAM software (g‐code) and outputs it as electronic signalsthat actually control the motors on the machine. Thistypically happens by sending “pulse” and “direction”signals through a parallel port cable to the machineelectronics. Mach3 has come to dominate the DIY CNCmarket, as it is a very robust program and is affordablypriced. Many people use the free demonstration versionof the software, but it is recommend to purchase the fullversion if funds allow. The demo is crippled to running500 lines of code. This might seem like a lot, and might besufficient for milling very simple parts with mostly straightcuts, but it will quickly be found to be severely limiting forcutting anything more complex. Even small parts withvery complex 3d shapes may easily require tens or evenhundreds of thousands of lines of code. Another lessknown, but just as important, restraint of the demoversion is that it limits the processing speed of howquickly it outputs signals to your machine’s motors. Thiscan directly limit machine performance.

Software overlapOften, software use isn’t quite as direct as the workflowdiagram might indicate. Many CAM software programsprovide tools for doing basic CAD work. While this can behandy for making minor changes after importing geometryto the CAM program, it is rarely powerful enough to use itas the sole design tool. Anything more than minorchanges are best done back in the original designsoftware, and then re‐exported to the CAM program.

Similarly, control software sometimes has basic tools forconversion of .dwg format line drawings to g code. Again,this isn’t the primary job of the software, so while it maywork adequately for very simple jobs, it should not berelied on exclusively. Control software typically alsocontains a g‐code editor for manipulation of the code.

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11CAD/CAM workflow

Cost of softwareAs might be surmised by this point, the cost of thesoftware necessary to design, generate toolpaths, andthen control the machine can be very, very expensive,especially if needing to create parts of any complexity.Before constructing a CNC machine, it is highlyrecommended to look into the costs of the softwareprograms that might be required, as they can easily farexceed the budget for machine construction. Mostsoftware vendors have functioning demonstrationversions available for download, and it is alsorecommended to try them before purchasing. Some aremuch more user friendly and intuitive than others,which have very steep learning curves.

While software with advanced functionality can be veryexpensive, there is a substantial and growing quantityof lower budget programs available. Some of these areeven free. While they are often lacking certain features,a significant amount of complex work can often beachieved with then by employing some creativity in howthey are used. Workarounds can often be discoveredthat can compensate for functionality that they maylack. The supplier list at the end of this manualincludes a list of software suppliers.

Learning G‐codeAnother alternative when cutting simple parts is tohand write g‐code. Doing this can eliminate the needfor both design software and CAM software. Beforethe development of sophisticated CAM software, thiswas how numeric machine control code was generated.The number of applications of this technique areprobably limited these days, but it can be a usefulmethod to know. Even if hand writing numeric code isnot a primary working method, understanding the G‐code language can be useful as it can allow quickediting or modifying parts of the code such as feedrates, without having to go through the post‐processing step again. Combined with other computerprogramming skills, learning g‐code could also allowwriting scripts to generate toolpaths and g‐code fromwithin 3d modeling software such as Rhino.

computer

motor drives &power supply

machine motors

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12machine electronics basics

Electronics

While an in‐depth discussion of machine control electronicshardware is beyond the scope of these plans, an overview isimportant for a basic understanding. For the most part, thisdiscussion will stay somewhat abstract, although in themachine assembly instructions the specific installation of twotypes of drive boards, a Xyoltex and a Gecko G540, will becovered. Due to the complexity of choosing individualcomponents that will function well together, it is highlyrecommended to purchase a pre‐packaged kit from a supplierthat includes all of the electronics as a matched collection.

While specific components of an electronic drive motioncontrol system for a homebuilt CNC machine can vary widely,the abstract diagram to the left illustrates the basic principlesof what is included.

In general, these are:

1. A computer to send motion data to a hardware componentcalled a “motor drive.”2. A power supply to provide the required voltage & currentto the motors.3. Electronic motor drive(s) that forwards the motion data tothe motors at the required voltage/current.4. The motors.

This is the general flow of information from the computer tothe motors. In addition, there are typically hardwarecomponents to provide data feedback from the machine tothe computer. All systems should be equipped with limitswitches at the end of each axis travel, to provide safety toboth the machine and operator. More sophisticated drivesystems may have feedback sensors that give more accuratecontrol of the motor positioning.

Working backwards from the motion of the machine:

MotorsMost home‐built machines are controlled by stepper motors.These are simple type of DC motor that requires a pulse ofelectricity to move it one “step”. A typical stepper motor has200 steps per revolution, so to cause continuing rotation in astepper motor it requires a fast stream of discrete electricalpulses. The frequency of the pulses will determine the motorspeed.

These motors are easy to electronically control via computer,and relatively inexpensive, but they do have some drawbacks.One is that there is the possibility of them “losing steps”under a load. This happens due to the stream of electrical steppulses continuing to flow to the motor even though it istemporarily being prevented from moving. Since the numberof steps required to move the machine is very high, a very smallnumber of missed steps may not have any noticeable impacton the finished part. On the other hand, enough missed stepsmay be catastrophic. In the best case, it may result in a lessthan perfect part, and at the worst it may result in machinecollisions, since after the event that causes lost steps themachine location is not corresponding to where the softwarethinks it should be. Missed steps is a problem with steppermotors because they typically lack any sort of feedbackmechanism. They simply do as they are told, and the controlsoftware has no way of recognizing any error that may occur,or way of correcting the motion. Some more advancedsystems employ a sensor that informs the software of theposition of the motor or machine, so that it can compensatefor any deviation and return it to proper location.

Another problem that steppers often suffer from is “mid‐band resonance.” This occurs when the frequency of steppulses causes a dynamic resonance within the motor. Thismay cause it to move erratically or even lock up completely.This is obviously an even bigger problem than a few missedsteps. Some stepper drives have circuitry that is designed tocombat this phenomena. Many hobby level drives do not.

Many industrial machines use servo motors rather thansteppers. They do not run in discrete steps like a steppermotor, but rather are more similar to a conventional motordesign. These can be either DC or AC designs, and typically runat a much higher rpm than steppers, necessitating a gearreduction of some sort. Due to both of these factors, servomotors consequently have a much smoother operation thansteppers. The major advantage of servos is that they typicallyhave a positioning feedback loop. They employ a device calledan “encoder” that monitors the position of the motor. Anydiscrepancy between the theoretical position of where themotor should be, and where it is measured as being, can becompensated for, and brought back to the correct position.However, servos are still much more expensive systems to setup on a home‐built machine. They require more sophisticatedelectronics equipment to drive them and more knowledge toset them up and “tune” them.

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13electronics

Torque curve & power transmission

Like all electric motors, stepper motors have the characteristicof producing the greatest amount of torque at zero rpm.What this means is that the faster the motor turns, the lessforce it produces. Manufacturers provide graphs that showtheir motors torque output relative to rpm. Not all motorsare created equal, as some have torque output that falls offmuch more quickly relative to rpm increase than others.Therefore,when designing a power transmission system it iscrucial to know what rpm the motor will be turning for a givenmovement speed at the machine. “Gearing down” the systemmay not necessarily increase the machine’s “power” as thedecrease in the motors available torque at a higher rpm maybe greater than the mechanical advantage that is gainedthrough gear reduction. However, even though the motorproduces most torque when barely turning, the machinecannot be geared to maintain the motor at that speed. If themotor is turning that slowly then the distance between each“step” of its movement will translate to too large of amovement at the cutting tool. It will not have a fine enoughcutting resolution. So the system becomes a compromisebetween several factors.

The belt drive system on this machine was designed withexactly these factors in mind. It is felt to be a goodcompromise between machine speed, power available topush a tool through the material it is cutting, and avoidingmotor speeds that would be vulnerable to mid‐bandresonance.

A belt drive was also felt to be advantageous over a leadscrew system for this machine as it is more tolerant ofmisalignment. A lead screw must be aligned exactly parallelto the machine axis it is powering. By contrast, the belt canbe out of alignment by a significant amount, with zeronegative impact on machine accuracy or performance. Notethat misalignment will have a significant negative impact onbelt wear.

DrivesAll motors that are used for motion control require some typeof electronic drive board to control them. Drive boards take avariety of arrangements. They may incorporate control forseveral axes on a single board, or may be configured as anindividual board for each axis. The advantage of an separateboard per axis is that they can be replaced individually in caseof damage.

All drive boards do essentially the same thing. They receiveinput signals from the control software, which are low involtage and current, and in turn output these signals to themotors with higher voltages and currents that they require foroperation. As such, they mediate between the computer andthe machine. Their in‐between position also allows them tohandle signal inputs for additional functions such asemergency stop buttons and limit switches. Most driveboards are very vulnerable to any errors in mis‐wiring.Incorrect connections, or breaking a connection to themotors while under power, can cause an immediatedestruction of the electronics on the board. Followmanufacturer directions very, very carefully.

MicrosteppingAnother function of many drives is that they break up thenumber of steps per revolution that are required at the motorinto a greater number. So for instance, a drive may have“1/8” or “8x” microstepping, which would effectivelyincrease the number of steps per revolution that control themotor from its original 200 to 1600. This is advantageousin that it increases the resolution of the system and providesfiner control over the movement of the machine. Note thatthese micosteps are typically not an exactly equal sub‐divinding of the original 200 steps. Each microstep may varyfrom the others by a very small percentage. This discrepancyis typically so small that it is inconsequential and will notadversely effect the accuracy of the machine. However, whenincluding microstepping in the calculation of machineresolution, it should be understood that this number has avery slight variability within it.

Power supplyThis is as simple as it sounds. A transformer type powersupply device is matched to the needs of the drive board(s)and motors. It is worth noting that many boards thatoperate by “pulse width modulation,” such as the Xylotex,actually perform most efficiently at the upper limits ofvoltage that they can handle. In other words, running themat lower voltage will not necessarily provide any additionalprotection for the drive board. Stepper motors alsocommonly require many times more voltage than theirratings may indicate. For instance, a stepper motor that isdesignated as a 2.5 volt motor may require a 24 volt powersupply to efficiently power it.

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14electronics

Breakout boardSimple drive boards, such as those that have multiple axesself‐contained on a single board, may be designed for directconnection to the computer’s parallel port via a standardcable. When using multiple drives that each control anindividual axis, an additional piece of hardware called a“breakout board” may be required. This is merely a devicethat connects to the computer via a cable (typically parallelport) and then provides multiple connections to allow wiringto the drives, emergency stop stop switches, limit switches,spindle control relays, etc. These boards also often providean added layer of protection between the higher voltage driveboards and the vulnerable low voltage computer. They dothis through optically isolated connections.

Additional switchesDrive boards or breakout boards will furnish some means ofwiring in several important additional devices. An emergencystop button should be part of every system. It is typically alarge red button with a mushroom‐shaped head, that providesan immediate way of shutting down the machine in case ofan emergency. It should be placed in a location that is easilyaccessible while operating the machine. It can be wired toshut down all axes of machine movement, and can usuallyalso be wired to shut down power to the router to kill thespindle movement. If at all possible, your e‐stop buttonshould be wired in this manner.

The other switches that should be wired into the system arelimit switches. These are placed at the end of each axis’srange of movement, thus a 3 axis machine will typically have6 switches. A limit switch on the Z axis, in the direction ofmovement toward the machine bed, may be omitted as itwould require frequent repositioning due to changes in stocksize, cutting tool length, etc. These switches will stop themotion of the machine if it unexpectedly reaches the end of atravel axis. This can prevent serious damage to the machineas well as guarding against personal harm from brokencutters. In addition to acting as safety devices, theseswitches can do double duty as homing switches. These areused to return the machine automatically to its home XYZposition. Most control software can be configured to use theswitches in this manner.

The computerAll of these inputs and outputs either originate orterminate in the control software in the computer. Mostcontrol software for home‐built machines is written to beused on PCs, although Mac versions are becomingavailable. The most popular, Mach3, is designed forWindows based machines, and others such as emc2 areLinux based. A computer with a parallel port for outputto the machine electronics will typically be required. Thecomputer need not be the latest model, and in fact anolder model with Windows XP or even Windows 98 maybe preferable with some software. A desktop model isgenerally better than a laptop, as most laptops do nothave a high enough voltage output through their parallelports (if they even have one) to perform well. They alsooften have power saving features to extend battery life,which interfere with the pulse timing of the controlsoftware.

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15sound control

Machine enclosure and sound transmission principles

One of the important considerations while designing thismachine was the necessity for it to be enclosed, for thecontainment of both dust and noise. There are manyexisting examples of home‐built machines that have alsoincluded a cover for these reasons. However, theregenerally seems to be a fundamental misunderstanding ofthe basic principles of sound control. This is evidenced bythe technique that many of these builders have adopted:lining the inside of the enclosure with foam‐rubberacoustical "insulation” of the type with an “egg‐crate”texture. Unfortunately, this is an incorrect application ofthis material.

There are a couple of different types of “sound control.” Firstis the controlling of sound within a space. Sound wavesbounce off of surfaces and it is often desirable to have acertain type of control over how this happens. The moretimes a sound bounces off of surfaces before it reaches alistener's ear, the longer the “reverberation time” isconsidered to be. Sometimes a longer reverberation time isdesirable, such as in a concert hall, and at other times ashort or zero reverberation time is needed, such as in arecording studio which must be free of echoes. Lining wallsand ceilings with a material that absorbs sound waves willprevent them from being reflected back to a listener, andmakes the space more acoustically “dead.”

The other type of sound control is between adjoining spaces.This is sound transmission. An example of this would be asituation such as adjoining rooms in a building, where it isdesirable to have as little sound make its way from one roomto another. This is a completely different situation fromcontrolling sound within a space, and this is the type ofsound control that the machine enclosure must provide,preventing the transmission of sound through it. The foaminsulation used by many builders is not intended to controlsound transmission, therefore it would be of significant useonly if a listener were placed inside the machine enclosure.Otherwise, it will mostly serve to collect a lot of dust.

There are three primary categories with which soundtransmission can be controlled:

1. Distance2. Isolation3. Mass

The first category is obvious. The farther away a sound isplaced, the quieter it is going to be. This category clearly isn’tof much help in designing a machine, as it can't simply beplaced farther away.

The second category is very important when it comes tomachinery. Vibrations can be transmitted through materialsand cause new vibrations to be produced a distance away.These new vibrations produce sound. To combat thistendency, many pieces of equipment have isolation mountsthat damp vibrations. These may be comprised of springs,hydraulic devices, or elastomeric materials such as rubber.Even if all sound could be contained within an enclosure,bolting the machine rigidly to a bench could have the effect ofturning the bench top into a large sounding board.

The third category is the one that is of primary importance tothis design. Increasing mass is a very effective way ofpreventing sound transmission, therefore the ideal situationis to make an enclosure out of a thick, massive material. Thishas its obvious problems, such as weight, needing to openthe enclosure, and needing to provide windows to see in.The window material will have a low mass, increasing thesound transmission of the enclosure as an overall assembly.Thicker window material can be used, at an increased cost.

What is of most interest is a sub‐category of the principle ofincreased mass, and that is the removal of any gaps orcracks. A gap is a zone of zero mass and has a majorconsequence on sound transmission. It has such an impactthat a 1/32" wide crack in the wall of a room can allow moresound through than the entire rest of the wall. To combatthis, the enclosure must be thoroughly sealed. The tighter itis, the more effective it will be at preventing soundtransmission.

Some home‐builders who have installed a foam lining claiman improvement. Small gains may be seen for a couple ofunintentional reasons. Depending on how it is attached, itmay be preventing surfaces of the enclosure from vibratingand producing sound. In effect it is providing some damping.More importantly, it is helping with the mass issue. While itprovides a small amount of direct additional mass, it iscovering up crucial gaps. Unfortunately, better results couldmost likely have been achieved with a simple roll of tape ortube of silicone caulk.

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16design alterations and construction

Can changes be made to the plans?

The following section outlines designinformation, and a principal reason forincluding it here is to provide some knowledgeof why the design exists as it does, and whysome aspects can and some cannot be changed.Many of the other plans on the market make aselling‐point out of stating that they can bewidely modified to suit individual needs.While this sounds attractive in principle, thereare serious problems with this approach. Theprimary one is that changing the size of themachine can have serious negativeconsequences on its performance. Increasing adimension can increase internal forces onmachine components, as well as increasing thedeflection of components. These stresses andstrains can be many times in excess of the whatwould be encountered in the machine as itexists in these plans.

In short, you should not make changes to theseplans unless you fully understand what theconsequences might be. The sizes of allcomponents have been optimized for theoverall size and use of the machine. Proceed tomake changes with extreme caution and at yourown risk.

Assembly steps

The assembly steps in these plans start with thefabrication of the wood components and finishwith the metal ones. This sequence was chosenbecause it presents a smooth, seamless order ofconstructing the machine.

However, it is highly suggested to read throughthe entire set of plans and then decide if thissequence makes the most sense for you. Ifthere is any doubt about the skills involved toconstruct the machine, then it is suggested tofabricate the metal components before the woodcomponents. This sequence provides a coupleof advantages: The first is that even though itmay be more unfamiliar to many builders, metalcan actually be easier to work. It has noperceptible grain and is therefore predictable inits behavior. Most of the metal parts arealuminum, which is a soft metal and hasrelatively low cutting forces involved, much likethose of a hard wood. The second reason is thatfabricating the metal parts will constitute thebulk of fabrication time and require the mostpatience to maintain build tolerances. Thenumber of cuts, holes to drill and tap, andamount of hand filing and finishing willultimately end up being a considerable amountof tedious time consuming work. This sequencewill also quickly reveal the level of skills andstamina to complete the metal components. Bythe time all of the metal components arefabricated, the wood fabrication will most likelyseem quick and easy.

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17design process

Designing a machine:

The design of a home‐built machine often has a designprocess that follows these steps:

a. Study existing designs that have been built by others.b. Construct something that looks similar.c. Be disappointed with some aspect of its performance.d. (Hopefully) build a second one.

Design can be a very complicated process, requiring notonly significant knowledge but good decision making skillsto balance the often conflicting criteria that are needing tobe met. Progress in any field is typically incremental, withthe breaking of revolutionary ground being the exceptionrather than the rule. Therefore, steps “a” and 'b” areboth inevitable and desirable. The question becomeswhat knowledge and skills are necessary to successfullycritique and improve upon existing designs?

Design Process and principlesThe following is a brief attempt at explaining the thoughtprocess and rationale behind this particular machinedesign. This is provided for two reasons. First, toperhaps provide a general starting point and advice forthose who decide to design their own machine. Secondly,to provide a foundation for those who may wish to makemodifications to these plans. What follows is a list ofpoints of understanding that were accumulated duringthe process of designing this machine. They range fromobservations of typical problem areas, to designphilosophy, to structural formulas and engineeringinformation. To those with engineering knowledge,please excuse any over‐simplifications of concepts. Thisinformation is aimed at those with little design expertiseand is not intended to transform anyone into a capableengineer or designer. Rather, it is intended to illustratehow complex it can be to design a seemingly simple deviceand how quickly one can get in over their head, evenwhen equipped with a little bit of over‐simplifiedinformation. Design hubris should be kept in‐check, infavor of the cautious and proven path.

Woodworking skillsThis may seem somewhat tangential to a designprocess, but it is not. Many builders of a CNCrouter, who are intending to use it to mill wood,possess very rudimentary woodworking skills.Many have never experienced trying to control ahand‐held router. It is important to have anintuitive understanding of the behavior of thematerial that will ultimately be milled with the CNCmachine, and how it interacts with a cutting tool. ACNC router is a very advanced piece ofwoodworking equipment, and success in using it isgoing to be much greater if the operator has a solidunderstanding of woodworking basics and a feel forthe material. Improving one's woodworking skillswill quickly reveal important understandings ofgrain, how the tool wants to follow it, in whichdirections it wants to tear, and why it is importantto control machine backlash some way other thanthrough electronic compensation. The forcesrequired to move a blade through wood, or to holdit back, may be unexpected, especially when it isspinning at 25,000 rpm in a router. Betterwoodworking skills will equate to a better feel forhow to electronically control a cutting tool, and willalso improve the build quality when constructingthe actual machine.

Use the router to build the machineIf constructing a CNC router, then obviously at somepoint a router will need to be purchased for use asthe spindle. By acquiring it early in the process, itcan be used to fabricate the machine itself. Manyof the wood parts for this machine can just as easilybe cut with a router as they can a circular saw or atable saw. Several of the cutting operations, suchas pockets, will actually require a router. With aguide‐fence and clamps, very accurate cuts can beachieved with the hand‐held router. Using therouter while building the machine will quickly revealthe differences between moving the tool left orright along an edge (climb‐cutting vs. conventionalcutting), the importance of feedrates and spindlespeeds, how to plunge into a workpiece, the effectof different types of cutting bits, and the generalforces involved.

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18design process

StiffnessOne of the biggest shortcoming of many home‐builtmachine designs is a lack of stiffness, or rigidity. Stiffnessis the ability to resist deflection. Materials have “elastic”behavior. At its simplest, pushing on them causes them todeflect. Release the force and they spring back. Push toohard and it doesn’t spring back. When this happens, it hasbent or broken, due to either exceeding the material'selastic limit and causing “plastic deformation,” or goingbeyond its yield point. ALL machines have some amount ofdeflection. A machine built of HDPE plastic has a very largequantity of it that may be easily seen by the naked eye.One built of MDF still probably has a considerable amount,and is often more than should be acceptable forconstruction of a machine. A machine that is built ofmassive cast iron and costs hundreds of thousands ofdollars still has some deflection, it is just infinitesimallysmall relative to its cutting accuracy.

A lack of stiffness causes several problems. The obviousone is that if the machine deflects under a cutting load,then the tool isn’t in the spot that the computer thinks it is.In other words, your cut is not going to be accurate. Theother big problem is “chatter.” A machine is a dynamicstructure, meaning there is motion involved. That motioncan cause vibrations and oscillations in the machinecomponents if it can flex excessively. At best, experiencingchatter may mean reducing cutting speed or taking cutsthat are not as heavy. At its worst it can destroy the cuttingtool, the part being cut, or even cause damage to themachine.

Stiffness comes from a combination of properties. The firstis the flexibility of the material itself, due to a propertycalled Modulus of Elasticity. The second factor is how thatmaterial is arranged in space, due to a property calledMoment of Inertia (or more correctly, the Second Momentof Area.) Thus the first factor is based on materialproperties, and the second on geometrical properties.Because stiffness comes from a combination of these twofactors, it means that to some extent having a surplus ofone property can make up for a deficiency in the other.

What this means is that even a very flexible material canbe arranged to produce a strong and rigid structure. Thisis why a machine built of MDF has to be so bulky, as itneeds to position the material in a way that canovercome its inherent flexibility. Unfortunately this isstill not as good as using an inherently stiff material in ageometrically efficient way. So yes, a somewhat rigidmachine can be built out of wood. No, never as rigid ascast iron, nor as compact.

JointsConnections between components are as important asmaterial choice. There is a huge difference in theamount of force that can be transmitted throughdifferent types of joints. One big limitation in usingwood for any structural application, whether a machine,a building, or a piece of furniture, is designing adequatejoint details. Subtle differences in how pieces cometogether can have a significant effect on strength.Creating strong joints in a material such as MDF is nosmall undertaking, but it can be done.

Basic structural design principlesSome understanding of very basic structural principleswill go a long way in designing a machine. A few simpleexperiments can help illustrate them. Attempting totwist a cardboard box with no top is relatively easy.Taping a top in place so that all six sides are solidplanes makes it many times more resistant to beingtwisted. This has increased the torsional strength of theassembly. Attempting to flex a ruler that is lying flat andspanning between two supports is also relatively easy.Repeating this with the ruler standing on its edge showsno perceptible deflection. This has increased thebending strength of the member. Attempting to hold apiece of thin paper straight out, while holding at onlyone edge, and it will droop down. Putting a 90 degreecrease, or a curve, in the paper that is perpendicular tothe edge being held, and it will now rigidly cantileverout. This change in geometry has made it into a form‐resistant structure.

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19design process

Building a modelIt is common to build a virtual 3d model of a potential design,with software such as SketchUp, Rhino3d, Solidworks, etc.However, one of the big problems that comes with the easyavailability of 3d modeling software is that it does not giveany sense of materiality and real‐world behavior. Everydesign works perfectly on the computer screen. The resultbeing that endless variations of a design are drawn without areal understanding of its basic shortcomings, and fewimprovements are made from one iteration to the next.

Before dedicating significant time to constructing a CNCmachine, it can be very valuable to evaluate the design byconstructing a small‐scale physical model. In addition torevealing potential problems with overall constructability orinterference of parts, it can give a sense of its structuralperformance. By building it out of a material that has someinherent flexibility, it will be easy to witness how thegeometry of the design effects the stiffness. Materials suchas 1/16” chipboard (material that cereal boxes are madefrom, can be sourced at a good art supply store,) mat board,posterboard, or bristol board are excellent for this purpose.Avoid stiff materials like foam core. The more flexible thematerial, the easier to see an exaggeration of where thedesign will flex. A model does not need to be constructed sothat parts slide or move, it can be fixed in mid travel.However, it should be constructed in a manner that mimicshow the material will really come together at joints, as thiscan be a significant location of flex.

A model built as just described can be pushed, twisted, andflexed to see where the design lacks stiffness. If it seemsexcessively flexible, making modifications to the physicalmodel, or constructing a new version, can be a quick way ofmaking significant advances in improving the design. Thismethod will often reveal areas of weakness that were notanticipated, and this will be happening during a phase wherethey are easily corrected. Once an actual machine isconstructed, making structural changes may be nearlyimpossible. Attempting to push a physical model to the pointof breaking can also be instructive. If it takes significantforce, and feels like it does not flex at all beforecatastrophically exploding, it is a good indicator of the overallstiffness of the assembly. If it softly crumples, or easilycomes apart at the seams, more design work is probablyrequired. It is possible to build a posterboard model that isnearly impossible to break in your hands.

Matched level of componentsA common problem with DIY machine design is the necessityof specifying individual components that work well inconjunction with each other. A machine should have aconsistent level of accuracy, or rather of inaccuracy, in itscomponents throughout. A scenario like installing expensivehigh accuracy ball screws for motion control on an MDFmachine will never realize the benefit of the high qualitycomponents. The amount of flex in the MDF material, or itsdimensional instability due to moisture in the atmosphere,will far exceed the tolerances that the ball screws can attain.The levels of accuracy between the two components may beoff by orders or magnitude. The quality level of allcomponents needs to improve together in order to seeimprovements in overall accuracy of the system, otherwisemoney is merely being wasted.

Here is a basic list of aspects that should have somewhatclosely matched accuracy levels:

‐Frame material. ‐Rigidity of frame design (NOT the same as frame material) ‐Ability to align and adjust the machine. ‐Type of bearings or guides. ‐Method of driving motion. ‐Backlash, or the amount of play in the machine. ‐Electronic resolution of steppers or servos. ‐Machine speed. ‐Spindle power.

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20design process

Tolerance and accumulation of errorBeyond creating a rigid machine that will not deflect under aload, there are other factors in design. One is the issue oftolerance. Many home‐built machine designs make claimslike: “cuts accurate to .000025". A number like this ismerely a theoretical electronic resolution of the steppermotors, and has no bearing on actual accuracy of the overallmachine. It in no way translates to accuracy at the tip of thetool, which is where it counts. What does effect accuracy isthe individual tolerances of the various parts of the machineworking together. Sometimes inaccuracies willserendipitously cancel each other out, as an inaccuracy inone direction will be counteracted by an inaccuracy in theother direction, the net result being that the error is notlarge. But this is an uncommon situation, and the individualerrors are more likely to accumulate and add to each other.So a theoretical accuracy tolerance for the machine is bestarrived at by adding all of the possible causes of inaccuracyto arrive at a total possible inaccuracy number. Here are afew things that contribute:

‐The machine flexing: frame, motor mounts, etc.‐Play: space between bearings and rails.‐Linear motion inaccuracy: rails not straight, variation in dimension, not parallel or in‐plane.‐Linear drive inaccuracy.‐Electronics error.

Degrees of constraintOne common problem in many DIY designs is having themachine bind under a cutting load. Each axis of themachine needs to smoothly roll on a bearing system, andeach axis needs to have bearings configured in a way thatwill constrain the motion so that it will only go exactly in thedirection of that axis. This typically requires many bearingsthat are spread somewhat far apart. All works well with thisarrangement until forces on the machine cause flexing, andsome components are no longer in exact alignment with thedirection of travel, causing binding. The arrangement ofbearings on the Y axis of the design in this manual aresomewhat unconventional. They are arranged so that theright side of the gantry is fully constrained against rotationin two directions. The gantry in effect is then cantileveredout from this set of bearings. The bearings on the left sideof the gantry act as outriggers that stabilize its position. Thebearing configuration on the left is not fully constrained initself, but provide constraint to the overall system in thethird direction of rotation.

Removing one direction of constraint from the left isintentional. It has been done this way so that the machinecannot bind if there is excessive flexing of the gantry.Flexing of the gantry will allow a small rotation in onedirection to absorb this force. While under these conditionsthere may be some inaccuracy in the cut due to deflectionof the gantry, the machine will keep moving and not bind.Accepting this very minor inaccuracy was felt to be a bettersituation than having the machine bind, which most likelywould result in a completely unusable part. When amachine with stepper motors binds, what can often happenis that the computer keeps feeding the signal to the motorsbecause it does not know that there is a problem. If themachine suddenly starts to move again, it is now receivingcode that is out of sync with where in the cutting process itleft off. The result is a large cutting error. Do not addadditional bearings to the left side of the machine unlessyou understand the implications for doing so. It will requiremuch more accurate alignment of the machine to preventbinding.

Alignment.Aligning a typical home‐built machine can be problematic.Smooth bind‐free operation requires accurate alignmentbetween bearing surfaces on each axis. It requires gettingthe machine parallel, square, and in‐plane. This can be avery difficult task to accomplish. Nearly all home‐builtmachines provide some means of providing adjustability,however, many use methods that make fine adjustmentvery difficult or impossible. Some do not provide enoughdirections of adjustability. The biggest problem is thatnearly none of them provide any sort of reference plane tomeasure from. It does no good if the machine cantheoretically be aligned, but there is no practical way ofmaking measurements to find that alignment. This designattempts to solve these problems in several ways. Usingthe manufactured faces of stock metal pieces providessome amount of automatic alignment between parts. All ofthe bearings have a set screw to allow very fineadjustments of their pre‐load against the axis rails that theyride along. Finally, by pouring a thin self‐leveling layer of avery low viscosity epoxy on the bed of the machine, it canbe used as a consistent reference plane from which to baseall alignments.

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21structural design

Structural design

Rigidity:For the design of the machine in these plans, rigiditybecame the primary design factor, as everything springsfrom the stiffness of the machine. Accuracy goes hand inhand with flexibility. It does not matter if your electronicscan control motion to .0001" if your machine frame flexes1/8" under a cutting load. This seemed to be the biggestdownfall of the existing home‐built designs. Manymachines were being built primarily of MDF (mediumdensity fiberboard.) This material is by nature veryflexible. The manner in which it was being arranged oftendid not help the situation.

As mentioned earlier, there are two factors at play toachieve stiffness. One is a property called modulus ofelasticity. This a property of the material and isessentially a measure of its flexibility. A higher numberindicates a stiffer material. A stiffer material is obviouslydesirable when building a machine. The second factor atplay is moment of inertia. This is a measure of stiffness ofa shape or geometrical arrangement of the material inspace. The same amount of a material can be used withdiffering amounts of efficiency. An example was givenearlier of the bending efficiency of a ruler, comparing itwhen supported on its flat side vs. when on its thin edge.This phenomenon is happening due to the moment ofinertia of the ruler being greater in one direction than theother. Another example would be to flex a thin steel rod.A steel rod that is about 1/4" in diameter can easily beflexed and bent by hand. However, that same quantity ofmaterial can be made into a large diameter hollow tubewith a thin wall thickness. This tube would not be able tobe flexed by hand. Both have the same amount ofmaterial, but the tube has a much higher moment ofinertia.

To get an idea of the range of material stiffness, here is amodulus of elasticity chart. All values are in psi:

Rubber 1,500‐15,000Low density polyethylene 30,000HDPE 200,000Polypropylene 217,000‐290,000Nylon 290,000‐580,000MDF (wood composite) 530,000Oak wood (along grain) 1,600,000Pine wood (along grain) 1,300,000Magnesium metal (Mg) 6,500,000Aluminium alloy 10,000,000Brass and bronze 17,000,000Titanium (Ti) 15,000,000‐17,500,000Copper (Cu) 16,000,000‐19,000,000Wrought iron and steel 30,000,000

Looking at this chart, the inherent problems of usingmaterials like plastic or MDF for machine constructionbecome immediately apparent. They are orders ofmagnitude more flexible than even the lowest modulusmetals. The philosophy in the design of this machinewas to use materials of high modulus wherever possible.One counter‐intuitive outcome of this is that it is oftenactually less expensive to use small quantities of highermodulus materials than large quantities of low modulusmaterials. Designing using higher modulus materials alsoallows the machine to be more compact, which canfurther help in reducing flex.

It is important to understand that the ability for amaterial to resist deflection is not exactly the same as its“strength.” These are two separate measures ofmaterial properties. For our purposes, the ability toresist deflection is what is more important. If there isenough material to provide a stiff enough design, there isvery little chance of it not being “strong” enough, so wecan ignore that structural need.

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22structural design

Moment of InertiaAs briefly discussed on the previous page, the second factor inachieving stiffness is how the material is distributed in space.This is called moment of inertia, or more correctly, the secondmoment of area. As also mentioned, since most designs aredriven by stiffness requirements rather than strength needs(the concept here is that if you built it so that it is stiff enough,it is going to automatically be strong enough) the focus herewill be on stiffness. Unfortunately, comparing the moment ofinertia of even very basic design options against each otherrequires some math. A few simple equations will be introducedhere. Hopefully this will provide some (relatively) easyinformation to see the implications of alternate designdecisions. These formulas will help compare scenarios such asincreasing the dimensions of member, comparing solid shapesto hollow sections, and how much deflection increases if a spanis increased.

To find solutions to these questions, two types of informationare required. First is the modulus of elasticity, which is aproperty of the material. The second is the moment of inertiawhich is a property of the cross sectional shape of the part.This information works in combination with other factors suchas the overall length of the part, how a load is applied, andhow its ends are supported.

Example:A simple piece of metal bar stock that has each endresting on a support. A single load is pressing down inthe center of it. What factors make it flexible or stiff?

‐Section dimensions. Increasing its size in section willmake it stiffer. A 1" x 1" bar will be stiffer than a ½" x ½"bar.

‐Section shape. Making the bar taller will make a muchbigger difference in making it stiff than will making itwider. (Think back to the ruler example). Another goodexample of this is a floor joist. A 2x12 floor joist is goingto be stiffer than a 2x6 floor joist.

‐Length. A longer piece is going to be more flexible than ashort one.

‐End constraints. The bar in this example is just restingon a support at each end. This means it can rotateslightly as the bar deflects. If the bar was held rigidly ateach end, like if it was welded solidly to another object, itwould make it more resistant to flexing.

‐Load. A load that is spread out over the length of amember will cause less flexing than if it is allconcentrated at the mid‐point.

The calculation of deflection is a three step process:

1. Look up the material's modulus of elasticity in a chart.

2. Calculate the section modulus based on cross sectionshape.

3. Calculate the deflection. The deflection formulas takemany of the factors such as end constraints and loadingconditions into account, so it is just a matter of findingthe formula that matches the situation.

21 3Calculate moment of inertiaFind modulus of elasticity Calculate deflection

a

a

b

d

aa

a

a

b

d

d

D

I = a12

4

cross sectionalshape

formula

I = bd12

3

I = a12

4

b

b

I = a124 b 4

I = bd123 hk 3

k

h

I = d0.049 4

d I = d0.049 4D4( )

I =E =

L

W

= W L48 E I

3

L

W

= W L192 E I

3

max. deflection =

L

W

= W L3 E I

3

simply supported at both ends,force applied at center of span.

fixed support at both ends,force applied at center of span.

fixed support at one end,force applied end of cantilever.

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23structural design formulas

LDPE 30,000HDPE 200,000Polypropylene 217,000‐290,000Nylon 290,000‐580,000MDF 530,000Oak wood 1,600,000Pine wood 1,300,000Magnesium 6,500,000Aluminium 10,000,000Brass & bronze 17,000,000Titanium 15,000,000‐17,500,000Copper 16,000,000‐19,000,000Wrought iron 30,000,000Steel 30,000,000

Units:All dimensions on this page are in inches.

Modulus of Elasticity units are in lb/in2

0.5

0.5

I = a12

4

L

W

= W L48 E I

3

I = 0.512

4

I = 0.00520833

Aluminum E=10,000,000

1

2

3

= (10) 24(48) (10,000,000) (0.00520833)

3

= 138,2402,499,998

= 0.055"deflection

Example:

-simply supported at ends-force applied at center

1/2" square aluminum

W= 10 lb at centerL= 24" long

step

step

step

Now, lets change the materialto 1" square aluminum.All else stays the same.

1.0

1.0

I = a12

4

L

W

= W L48 E I

3

I = 1.012

4

I = 0.0833

= (10) 24(48) (10,000,000) (0.0833)

3

= 138,24039,994,000

= 0.003"deflectionNote that the originalexample had over 17times as much deflectionas the second!

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24deflection example

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25structural design conclusion

structural design conclusion

These calculations on the previous pages are adequatefor very basic cross sectional shapes and simple loadingsituations. Essentially they are for finding deflection insimple types of beams. Unfortunately, the real world israrely that cooperative. As soon as the cross sectionbecomes more complex (like an I‐beam for example,) ormultiple pieces are attached together (like the gantry onthis design,) calculations become much morecomplicated. Determining the deflection in thesecomposite assemblies is beyond the scope of this simpledemonstration. Similarly, any introduction of loads otherthan the very idealized conditions shown in the formuladiagrams also makes calculation tremendously morecomplicated and is beyond our scope.

Not only do cross section properties complicate thecalculations, but there are complexities even withinwhat may seem to be an adequate solution according tothese calculations. For example, increasing the size of ahollow section while reducing its wall thickness will resultin a stiffer member. However, there are limits to this.Wall thickness can not be reduced too far or the memberwill be vulnerable to buckling under a load. So while thebasic deflections calculations show it to be adequate,there are other factors that may reject this as a solution.

Among those other factors, it is unusual, indeed difficult,for any part to be designed so that there is only one typeof stress involved. A good example of this would be atruss, which operates on the principle that its membersare either in pure compression or pure tension. Inpractice this is very difficult to achieve and there isnearly always some amount of bending force introduceddue to the realities of joint design.

In the case of a CNC machine such as this one, the gantryexperiences a combination of torsion and deflectionforces. Not only do the cutting forces push on it causingit to deflect, but those forces are not aligned directlywith its centerline. The cutting forces are cantileveredsome distance down the Z axis. This eccentric loadingintroduces a torsional twist into the gantry.

Understanding and calculating combinations of forcescan be very complex and is well beyond the averagehome‐builder's analytical abilities. It is important tokeep in mind that this is nearly always the rule ratherthan the exception, so the structural calculations shownhere should be viewed as a guideline for understandingsome very basic principles. It can be used as a roughmeans of comparing the effects of changing sizes ofmembers. This should in no way be seen as a definitiveguide for structural design, if anything it should betaken as an illustration of just how difficult it can be tounderstand even simple loads on a part.

A successful design also depends on creating joints thatcan transmit loads between parts in an effective andappropriate way. This is one other aspect that thesesimple calculations do not consider. Also keep in mindthat all of this information pertains to static conditions.Remember that a machine tool is a dynamic conditionand makes it much more complex to predict itsstructural behavior. Kinetic movements and rotatingparts can introduce momentum, vibrations, andoscillations that can amplify static stresses to the pointof breaking failure. Discussion of dynamic behavior iswell beyond the scope of this set manual.

As stated earlier, the intent of providing thisinformation is twofold. First, it is here to illustrate thatwhat may seem simple can be quite complex tocalculate and predict. Please bear that in mind whentempted to make changes to the plans. The secondreason for providing this knowledge is that it can give atleast some sense of the implications of making changes.It is quite easy to do a few calculations and see thatdoubling the length of part makes it much more flexible.To directly see those numbers and be able to comparethem may just aid in your judgment of how fardimensions can deviate from those in the plans beforethe cross sectional size of a member needs to change.In the ideal situation, this knowledge might help youimprove upon the design as given

Naming conventions foraxes and directions followthese standardsthroughout:

X

Y

Z

front

rear right

left

GENERAL NOTES

‐ Do not measure off of printed drawings. Use dimensions asindiacted on drawings. Scale is not indicated on drawingsdue to variation in printer accuracy. Printing at 100% scalefactor may not guarantee exactly 100% on paper!

‐Do not make changes to the design without having a fullunderstanding of their implications. This machine wascarefully designed such that all components work togetheras a integrated whole. Changes may have unforeseenimplications later in the build process, or may negativelyaffect the operation of the finished machine.

‐Dimensions on mechanical parts are given in Imperialdecimal units. Dimensions are given to either 2 decimalplace accuracy or may be given as full decimal equivalentsto fractions. This does not indicate degree of tolerancerequired.

‐Tolerances. An accuracy of +/‐ 1/32" is generally sufficienton metal parts. Any exceptions to this will be noted. Cutwood parts should aim for this same level of precision.

‐Counterbores. Many metal parts indicate counterbores.These are OPTIONAL. Counterbores are present to reducethe thickness of material to be tapped, to make handtapping easier.

‐Filing to fit. If tolerances are not held accurately enough itmay be necessary to file some parts slightly duringassembly.

‐BE SAFE. Use good judgment while working and do notattempt anything that is beyond your ability or that mayjeopardize your personal safety.

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26general build notes

METAL

1018cold rolledrectangularbar

A36hot rolledangle

6063‐T52rectangulartube (1) @ 24.00" 24.00” total

6061‐T6square bar

(2) @ .75”(2) @ 1.25(1) @ 2.50”(1) @ 6.75”(1) @ 7.25”(4) @ 7.375”(1) @ 8.50”(1) @ 10.75”(1) @ 20.75”

96.00” total

6061‐T6rectangularbar

(1) @ 5.625” 6.00” total

.75" x .75" bar

1.50" x 3.00" x .125" wall

.125" x .75" bar

ALUMINUM

(1) @ 4.25”(misc) 4.5" 9.00” total

.1875" x 2.50" bar

(2) @ 24.00" 48.00” total

.1875" x 3.00" bar

(1) @ .75”(1) @ 1.00”(1) @ 1.25”(1) @ 1.875”(1) @ 2.50”

8.00” total

.375" x 1.25" bar

(4) @ 1.75”(2) @ 2.75”(1) @ 5.625”(1) @ 11.25”

31.00” total

.75" x 1.00" bar

(1) @ 2.00"(2) @ 2.25”(1) @ 6.75”(2) @ 4.25"

22.50” total

.75" x 1.25" bar

(2) @ 4.25 9.00” total

.75" x 1.75" bar

(2) @ 24.00" 48.00” total

(2) @ 24.00" 48.00” total

1.25" x 1.25" x .125" angle

.25" x 1.50" CRS bar

STEEL

(1) @ 12.00”(1) @ 22.50” 36.00” total

.25" x 2.50" CRS bar

NOTE:Total quantity for each size of stock is listed.Total quantities typically include additional material length to includewidth of saw cuts. These quantities can be used when orderingmaterial in bulk lengths. If ordering in bulk lengths, note that it isoften less expensive to round quantities up to the nearest whole foot.

Within each size of stock, individual part lengths are also listed. Thesequantities can be used if ordering material by individual part length. Ifordering by individual part length, note that most suppliers will onlyguarantee cut accuracy to +/‐ 1/16", and cuts may not be perfectlysquare or have high finish quality.

NOTE:Before ordering metal or other parts, consult the ADDENDUM onpage 171 of this manual. It outlines upgrading the machine withthrust bearings on the Z axis (HIGHLY RECOMMENDED.)A separate bill of materials is listed for these parts in the addendum.

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27bill of materials 1

(46) sealed roller bearings, ABEC‐7 skate 8mm x 22mm x 7mm (608 size)

MOTION

400XL timing belt‐ 200 teeth x 3/8" width, McMaster part # 6484K445500XL timing belt‐ 250 teeth x 3/8" width, McMaster part # 6484K451

OR

10 feet 3/8" wide x .200 XL pitch open ended timing belting.

(12') stepper motor wire, cont. flex, shielded, McMaster part # 7673K44.Limit switch wire.(5) limit switches, SPDT submini lever switch, Radio Shack part # 275‐016 (or similar).Emergency stop switch.

8" 3/8‐10 acme one‐start precision rod, McMaster part # 99030A327 (36" length)(1) delrin anti‐backlash nut w/ .925" square flange, DumpsterCNC part # AC38101‐LN(1) delrin shaft coupler, @stepper shaft dia., DumpsterCNC part # AC38101‐AC

OR

8" 3/8‐8 acme two‐start precision rod, McMaster part # 99030A315 (36" length)(1) delrin anti‐backlash nut w/ .925" square flange, DumpsterCNC part # AC38082‐LN(1) delrin shaft coupler, @stepper shaft dia., DumpsterCNC part # AC38082‐AC

OR

8" 3/8‐8 acme four start precision rod, McMaster part # 99030A303 (36" length)(1) delrin anti‐backlash nut w/ .925" square flange, DumpsterCNC part # AC38084‐LN(1) delrin shaft coupler, @ stepper shaft dia., DumpsterCNC part # AC38084‐AC

(2) 10 tooth timing pulleys, 3/8" wide, .200 XL pitch, bore dia. to match steppermotor shafts

ELECTRICAL

wood filler.carpenters wood glue.paint and primer.24 fluid oz. (32 fluid oz. recommended) low viscosity epoxy resin & hardener,

<600 cps viscosity.30" piano hinge.(2) 1 1/2" utitlity hinges.(2) 2" utility hinges.(2) magnetic door latches.cable ties.

MISC.

PLYWOOD

PLASTIC

(2) 4' x 8' sheets, 3/4" sanded finish plywood, such as“cabinet grade.”

Note on plywood:While "cabinet grade" is specified, the important qualities tolook for in plywood is that it has a sanded finish on bothfaces, preferably a high count of core plies, and core plieswith no voids.

Nominal 3/4" plywood is often marked and measures 23/32".This thickness, or close equivalent metric sizes, will notaffect the construction of the machine base. To the greatestextend possible, the design allows for such small variation inmaterial thickness.

(1) 24"' x 24"' sheet, polycarbonate.~1/8" min. thickness, ~3/16" preferred.

Min. recommended stepper motor size: 275 oz./in.

Stepper motor choice may depend on the type of materialsthat you intend to cut with the machine. For very softmaterials, such as foam, the machine may perform adequatelywith stepper motors with a lower rating than the suggested 275oz./in.

Stepper motors, motor drive, and power supply must all becarefully matched to each other for proper motorperformance. Information on making these decisions isbeyond the scope of this manual. For this reason, it issuggested that motors, drive(s), and power supply be purchasedas a prepackaged kit from a reputable source.

ELECTRONICS

HARDWARE

hex head bolts(1) #10‐32 x .75” (or 5mm x 20mm)(14) 1/4‐20 x .5” bolts (modified, see page 86)(28) 5/16‐18 x 1.5” (8 modified, see page 86)(1) 5/16‐18 x 2.5”

socket head cap screws(2) #10‐32 x .75”(7) 1/4‐20 x 1/2”(1) 5/16‐18 x 2.5”(4) 5/16‐18 x 3”

soc. head cap screws (OR machine screws)(4) #4‐40 x 1”(8) #10‐32 x 1”(4) #10‐32 x 2.5"

lag bolts(30) 1/4” x 1.25”

nylon insert lock nut

(4) #4‐40(8) #10‐32(48) 1/4‐20(35) 5/16‐18

flat washers (SAE)(4) #4(20) #10(100) 1/4”(100) 5/16(6) 3/8" (modified, see page 86)

lock washers(4) #4(12) #10(28) 1/4”

soc. head cap screws (OR hex bolts)(1) 1/4‐20 x 1”(1) 5/16‐18 x 2”

fender washers(2) 5/16

grade 8 hardware

(4) 5/16‐18 x 3” bolts(8) 5/16 washers(4) 5/16 lock washers(4) 5/16‐18 hex nuts

set screws (grub screws)(50) #10‐32 x 3/8"(2) #10‐32 x 3/4"

HARDWARE

roll pins(4) 3/16" x 2"

threaded rod (allthread)(96") 1/4‐20 (total length)nails

(1 lb) 6d bright finish

wood screws(1 lb. box) #10 x 1.25"(1 lb. box) # 10 x 3"

Acme rod choice is a compromise between speed and resolution. Single‐start willhave a finer resolution, but slow travel speed. Four‐start will move quickly withslightly less resolution. In general, the two or four‐start will still have enoughresolution for most needs, and is thus recommended (four‐start preferred).Also, low torque stepper motors (below 300 oz/in) may require single start ordouble start, for additional mechanical advantage.

NOTE:Consult ADDENDUM (page 171) for additional Z axis thrustbearing parts that are not listed in this bill of materials.

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28bill of materials 2

FABRICATED METAL PARTSpart # part name # reqd.01 gantry bottom 202 gantry tube 103 gantry left top 104 gantry right top 105 gantry spacer 106 gantry outer right 107 Y motor mount front 108 Y motor mount rear 109 X belt plate 110 X belt clamp 111 Y rail 112 carriage block rear upper 113 carriage block rear lower 114 bearing block 315 bearing block tapped 116 carriage block front right 117 carriage block front left 118 spacer upper 219 spacer lower 220 Z motor mount right 121 Z motor mount left 122 Z cable plate 123 Y belt clamp 124 Z rail 125 Z rail block 126 nut plate block 127 nut plate 128 X rail 229 X rail angle left 130 X rail angle right 131 X plate right 132 X plate left 133 X belt pulley adjuster 134 cable arm 1 135 cable arm 2 136 cable arm mounting block 137 router mount Ridgid R2401 238 router clamp Ridgid R2401 239 router mount Bosch Colt top 140 router mount Bosch Colt bott. 141 router clamp Bosch Colt top 142 router clamp Bosch Colt bott. 143 X limit switch bracket 244 Y limit switch bracket 245 Z limit switch bracket 1

GAN

TRY

CARR

IAGE

Z AX

ISX RA

ILS

FABRICATED WOODEN PARTSpart # part name # reqd.A bottom skin 1B Y rib 1 2C Y rib 2 2D X rib 1 2E X rib 2 5F top skin 1G wall plate 3H vertical rib 6I right wall plate 1J right top plate 1K left top plate 1L left skin 1M rear plate 1N rear plate door 1O left inner skin 1P right inner skin 1Q right skin 1R front plate 1

BASE ASSEM

BLY

COVE

R

STUD SCHEDULEpart # length # reqd.SA 1.25" 5SB 1.5" 1SC 1.75" 12SD 2.25" 2SE 2.5" 2SF 2.75" 3SG 3.25" 4SH 3.50" 2SI 8.00" 1

LIST OF FABRICATED PARTSMODIFIED HARDWAREpart # part name # reqd.H1 thin head bolt 8H2 shortened bolt 14W1 enlarged washer 6

S cover front 1T cover top 1U cover side 2V cover side filler 2W cover rear 1

ROUTER

ROUTER STUDSpart # length # reqd. ModelRSA 2.75" 4 Ridgid R2401RSB 3.00" 4 Bosch Colt

(1/4‐20 studs)

(1/4‐20 studs)

FABRICATED PLASTIC PARTSpart # part name # reqd.P1 cover window front 1P2 cover window top 1P3 cover window side 2CO

VER

NOTE:Consult ADDENDUM (page 171) for additionalfabricated parts that are not listed here. (for additionof Z axis thrust bearing)

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29Fabricated Parts list

01 gantry bottom

stud SG (3.25")

02 gantry tube

03 gantry left top

11 Y rail

stud SH (3.50")

stud SC (1.75")

01 gantry bottom

04 gantry right top

05 gantry spacer

06 gantry outer right

09 X belt plate

10 X belt clamp

08 Y motor mount rear

stud SA (1.25")

stud SD (2.25")

07 Y motor mount front

5/16‐18 x 2.5" bolt.

stud SG (3.25")

(7) 1/4‐20 x .5" socket head cap screws.

1/4‐20 x 1" bolt

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30exploded gantry

15 bearing block tapped

stud SC (1.75")

13 carriage block rear lower

14 bearing block

stud SC (1.75")

20 Z motor mount right

21 Z motor mount left

16 carriage block front right

14 bearing block

stud SC (1.75")

14 bearing block

stud SC (1.75")

17 carriage block front left

18 spacer upper

23 Y belt clamp

stud SA (1.25")

stud SE (2.50")

22 Z cable plate

stud SG (3.25")

19 spacer lower

12 carriage block rear upper

(4) 5/16‐18 x 3"grade 8 bolts.

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31exploded carriage

Locations of all bearings indicated in red.

Look closely, some are obscured by otherparts. There are a total of 38 bearings inthis illustration, including the two that areused as a belt pulley.

All bearings are sealed ABEC‐7 skatebearings, 8mm x 22mm x 7mm.

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32bearing locations

24 Z rail

25 Z rail block

26 nut plate block

27 nut plate

stud SB (1.50")

stud SF (2.75")

38 router clamp RIDGID

37 router mount RIDGID

stud SC (1.75")

stud SA (1.25")

RIDGIDR2401

BOSCHCOLT

stud RSB (3.00")

stud RSA (2.75")

39 router mount BOSCH top

40 router mount BOSCH bottom

41 router clamp BOSCH top

42 router clamp BOSCH bottom

stud SH (3.50")

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33exploded Z axis

31 X plate right

29 X rail angle left

28 X rail

28 X rail

30 X rail angle right

33 X belt pulley adjuster

32 X plate left

5/16‐18 x 2.5" socket head cap screw.

5/16‐18 x 2.00" bolt.

#10‐32 x .75" hex head machine screw. (or 5mm x .8)

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34exploded X rails

34 cable arm 1

35 cable arm 2

36 cable armmounting block

stud SF (2.75")

stud SF (2.75")

stud SI (8.00)shorten as required forcable management.

washer W1

washer W1

washer W1

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35exploded cable arms

F top skin

D X rib 1

D X rib 1

E X rib 2

A bottom skin

B Y rib 1

C Y rib 2

B Y rib 1

G wall plate

H vertical rib

I right wall plate

H vertical rib

J right top plate

H vertical rib

G wall plate

H vertical rib

G wall plate

K left top plate

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36exploded base inner structure

R front plate

Q right skin

electronics bay door(not in Bill of Materials)

M rear plate

N rear plate door

L left skin

O left inner skin P right inner skin

Inner assembly.See page 36 forexploded view.

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37exploded base skins

U cover side

S cover front

Base assembly.See page 37 forexploded view.

T cover top

U cover side

V cover side filler

V cover side filler

W cover rear

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38exploded cover

0.75

6.254.25

0.75

14.75

0.75

1.5

0.75

1.5

0.75

1.5

.375

.375.75

3.1252.125

7.375

.375

0.75 0.75

.375

.375

.75 .75

.375

.375

.3125 DIA., 2 holes.

#10‐32 threaded, 2 holes (from bottom side).

.375 DIA., 2 holes.

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391 gantry bottom

stock size:.75 x .75

material:6061‐T6 alum.

# required: 2

part # 1

4.5 6.5 6.5 6.5 6.5 6.5 6.53.253.253.253.253.253.252.256

3

3.00

1.50

0.75

25.5

0.75

0.75.375 .37512.75 .375

0.875

4.252.125

.4375

4.5 6.5 6.5 6.5 6.5 6.5 6.5

0.875

4.25

0.875

4.25

2.125

.4375

2.125.4375

0.875

4.252.125

.4375

25.50.7512.75 .375

1.5

1.5

.75

.753.253.253.253.253.253.252.25

4824.00

.50 DIA., 7 holes..3125 DIA.


.3125 DIA.

.3125 DIA., 4 holes, cut & file to slots.

.3125 DIA., 4 holes, cut & file to slots.

1.75.875 .375 DIA., cut & file to slots.

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402 gantry tube

stock size:1.5 x 3.0 x .125


# required: 1

part # 2

0.75

6.254.25

0.75

14.75

0.75

1.5

0.75

1.5

0.75 0.75

7.3752.125

.375 .375

3.125

.375

.75

.375 .375

.375.75

#10‐32 threaded, 2 holes.

.375 DIA., 2 holes.

84.00

.375 DIA.

1/4‐20 threaded,CBORE .375 DIA x .25 DP.,2 holes.

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413 gantry left top



# required: 1

part # 3

0.75

2.5

6.254.25

0.75

2.5

14.75

0.75

1.5

0.75

1.5

0.75

2.5

0.75

2.5

3.757.5

7.3752.125

.3751.25

.3751.25

3.125

.375

.75

.3751.25

3.75 1.8751.25

.375

.375.75

.375 DIA., 2 holes.

1/4‐20 threaded,CBORE .375 DIA x .25 DP.,2 holes.



.375 DIA., 2 holes.

1/4‐20 threaded,CBORE .375 DIA x .25 DP., 2 holes.

4 22.00 1.00

.25 DIA., 2 holes.

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424 gantry right top



# required: 1

part # 4

0.75

1.5

0.25

11.25

27.5

.75

.375

1.003.75

5.625

.125.3125 DIA, 2 holes.

4 22.00 1.00

.25 DIA, 2 holes.

1.75.875

Note that this part is notsymmetrical. Holes arecloser to one end.

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435 gantry spacer



# required: 1

part # 5

11.25

0.75

44

0.750.75

27.5

5.251.5

2

0.75

1.5

0.75.375

.375 .375

.375

5.625

2.00 2.00

1.00

.75

.375

2.625.75

1.003.75

#10‐32 threaded, 2 holes(from rear side).

.3125 DIA.,2 holes

1/4‐20 threaded,CBORE .375 x .50 DP, 2 holes.

.3125 DIA, 2 holes.File/drill to slots.

.375 DIA., 2 holes.

0.75.375

0.5.25


4

42.00

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446 gantry outer right

stock size:.75 x 1.00


# required: 1

part # 6

3.712

0.394

1.5

.75

1.856

.1875

2.51.25

4.52.25

0.606.303

#10‐32 threaded,CBORE .25 DIA. x .875 DP., 2 holes.(CBORE from bottom).

1/4‐20 threaded, CBORE .3125 x .75 DP.

1.25.6250.75.375

0.75

1.5.75

.375

.125R

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457 Y motor mount front



# required: 1

part # 7

3.712

0.394

0.606

1.5

.303.75

1.856

.1875

2.51.25

4.52.25

#10‐32 threaded,CBORE .25 DIA. x .875 DP., 2 holes.(CBORE from bottom).

1/4‐20 threaded, CBORE .3125 x .75 DP.

1.25.6250.75.375

1.5

0.75

.75

.375

.125R

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468 Y motor mount rear



# required: 1

part # 8

1.25

2.5

1.25

1.75

3.75

1.25

.625

.625

.8751.875

0.75.375

enlarged beltgroove detail .

0.8.20 0.25

0.375.094

.063


1/4‐20 threaded.

0.75.375

1.25

2

.6251.00

.3125 DIA.

1.25

2.51.25

.625

1.5

0.5

.75.25

0.125.062

45°

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479 X belt plate & 10 X belt clamp



# required: 1

part #s 9,10

ea.

PART # 9 PART # 10

6.5 6.5 6.5 6.5 6.5 6.5 3

45

2.5

5

1.252.50

1.503.2522.50

3.253.253.253.253.25

0.5.25

1/4 ‐ 20 threaded, 7 holes.

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4811 Y rail

stock size:.25 x .2.50

material:1018cold rolled steel

# required: 1

part # 11

0.75

13.5

1.75 5.875

1.75

0.75

1.75

0.75

1.5

0.75

0.75

1.5

0.75

1.75

3.3756.75

0.75

1.75

6.75

.375.875

2.9375.875

.375

.875

.375.75

.375.75

.375

.875

3.375 1.6875

.875

.375

0.75

.375

.375

.375 DIA., 2 holes. NOTE: These two holesare NOT centered in the material thickness.

1/4‐20 threaded,CBORE .375 DIA x .25 DP, 2 holes.(CBORE from bottom).


.375 DIA., 2 holes.

#10‐32 threaded, 2 holes (back side).

.375 DIA., 2 holes.

0.5.25 0.813.3930.813.393

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4912 carriage block rear upper



# required: 1

part # 12

0.75

13.5

1.75 5.875

1.75

0.75

1.75

0.75

1.5

0.75

1.5

6.75

.375.875

2.9375.875

.375

.875

.375.75

.75

.375

.375 DIA., 2 holes. NOTE: these two holesare NOT centered in the material thickness.

1/4‐20 threaded,CBORE .375 DIA x .75 DP,2 holes.

#10‐32 threaded, 2 holes (from bottom).

.375 DIA., 2 holes.#10‐32 threaded, 2 holes (from back side).

.375 DIA.,2 holes.

0.5.25 0.813.3930.813.393

0.75.3750.75

0.75

1.75

.375.875

3.3751.6886.753.375

1.50

2.51.25

0.75

1.75

.375.875

1

1.5.75

.50

.375

2.625 8.25 2.6254.1251.313 1.313

0.3750.375

0.875

0.875.438

.438

.1880.3750.375

0.875

0.875

.188

.438

.438

.1875 DIA., 4 holes.R 0.25.125 R (Typ.)

1.25.625

ALTERNATIVE DESIGN:Rather than cut notches at thecorners of the part, leaverectangular. Add counterbores and(2) additional #10‐32 threaded holesas indicated. Requires use of longerbolts (2") at two bearing locations .

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5013 carriage block rear lower



# required: 1

part # 13

2

0.5

0.5

0.5

1.5

0.5

0.875

1.75

0.375

3.5

1.00 .75

1.75

.25.25

.4375

.875

.1875

.25

.25

2.751.375

.375 DIA.


#10‐32 threaded,CBORE .25 DIA x .25 DP,2 holes.

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5114 bearing block



# required: 3

part # 14

2

0.5

0.5

0.5

1.5

0.5

0.875

1.75

0.375

1.375

1.375

3.5

1.00 .75

1.75

.25.25

.4375

.875

.1875

.6875

.6875

.25

.25

.375 DIA.


#10‐32 threaded,CBORE .25 DIA x .25 DP,2 holes.

1/4‐20 threaded.

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5215 bearing block tapped



# required: 1

part # 15

0.5

1

1.756.875

11.25

130.75

1.625

0.75 13

1.625

3.875 7.25

11.25

17

0.75

1.5

0.75

1.5

8.50

6.50.375

.8125 5.625 .50

.25

.375.75

.8753.438

1.938 3.625

.375.75

.8125

.375

5.625

6.50

1/4‐20 threaded,CBORE .375 DIA. x .25 DP.,2 holes.

.375 DIA., 2 holes.

#10‐32 threaded, 2 holes (bottom side).


.375 DIA., 2 holes.


.375 DIA., 2 holes.

0.5.25

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5316 carriage block front right



# required: 1

part # 16

1.756.875

11.25

130.75

1.625

0.75 13

1.625

3.875 7.25

11.25

14.5

0.75

1.5

0.75

1.5

7.25

6.50.375

.8125 5.625

.375.75

.8753.438

1.938 3.625

.375.75

.8125

.375

5.625

6.50

1/4‐20 threaded,CBORE .375 DIA. x .25 DP., 2 holes.(CBORE from bottom).

.375 DIA., 2 holes.


.375 DIA., 2 holes.


.375 DIA., 2 holes.

0.5.25

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5417 carriage block front left



# required: 1

part # 17

0.75

1.5

0.75

1.5

1.5.75

.375

.375

.75

.75

.375 DIA.

NOTE:Use stock thickness as thisdimension to maintainconsistency between pieces.

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5518 spacer upper



# required: 2

part # 18

0.75

1.5

1.25

2.5

1.5.75

.375

.625

.75

1.25

.375 DIA.

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5619 spacer lower



# required: 2

part # 19

0.394

1.5

0.394

3.538

5.326

0.5

12

2.751.856

.197

.197

.75

1.00 .50

.25 0.75.375

R 1.25.625 R

.25 DIA., 2 holes.


0.75.375

1.856 1.682EQUAL EQUAL

2.0761.125

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5720 Z motor mount right



# required: 1

part # 20

0.5

121.00 .50

.25 0.75.375

0.394

1.5

0.394

3.7121.856

.197

.197

.75

R 1.25.625 R

5.52.75

.25 DIA., 2 holes.

1/4‐20 threaded,CBORE .375 DIA. x .25 DP.,

2 holes.

0.75

1.856 1.856

.375

EQUAL EQUAL

2

0.5

1 1.00.50

.25

0.5

1.5

.25.75

2.251.125

#10‐32 threaded,.75 deep, 2 holes.

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5821 Z motor mount left



# required: 1

part # 21

2.25

8.5

4.5

1.5

3

1

4.25

1.125

2.25

.75

.50

1.50

0.375.1875

1.50 DIA.

.25 DIA., 4 holes

.3125 DIA.

1.8561.856.928 .928

4.5

1.856

1.856

2.25

.9281.125

.928

R 0.25.125R

2.25

NOTE:Cut from 2.50" wide plate stock, as it isa more common stock size than 2.25"

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5922 Z cable plate



# required: 1

part # 22

enlarged beltgroove detail .

0.8.20 0.25

0.375.094

.063

0.5

1.5.75

.25

.125 R.

.3125 DIA.

1.25

2.51.25.625

0.75.375

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6023 Y belt clamp



# required: 1

part # 23

4.5 2.5

24

0.5

5

2.51.25

2.50

12.00

2.25 1.25

.25

1/4‐20 threaded, 5 holes.

1.75.875 12.256.125

0.75.375

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6124 Z rail



# required: 1

part # 24

22.5

1

2

1.5

.50

1.00

.75

11.25


0.75

2.512.251.754.52.25 .875 6.125 1.25.375

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6225 Z rail block



# required: 1

part # 25

2.5

0.75

1.5

0.75

1.75

4

1.25 0.5.25.625

1.25 .75

.375

.875

2.00

.375


1/4‐20 threaded, 2 holes.

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6326 nut plate block



# required: 1

part # 26

5

1.35

0.973

1.25

0.75.375

2.50

.675

0.675

1.875

.625

.338

.9375

0.875.4375

0.675

1.35.675 .338

.487

0.75.375


.50 DIA.

.125 DIA., 4 holes.

1.5.75

0.875

R 0.25.125 R

2.5

.4375

1.25

NOTE:Hole pattern is for DumpsterCNC anti‐backlash nut. Modification may benecessary if using a an anti‐backlash nutfrom another manufacturer.

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6427 nut plate



# required: 1

part # 27

1.5

7.5 7.5 7.5 7.5 7.5 1.5

.753.75 3.75 3.75 3.75 3.75 .757.5

4824.00

3.75

31.50

0.5.25

1/4 ‐ 20 threaded, 7 holes.

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6528 X rail



# required: 2

part # 28

48

2.5

2.5

0.251

0.246

1.25

1.25

.125

.125

24.001.5

7.5 7.5 7.5 7.5 7.5 7.5

1.5

1.5

.753.75 3.75 3.75 3.75 3.75 3.75

.75

.75


.3125 DIA., 7 holes. Grind/file 1/16" off of top edge.

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6629 X rail angle left

stock size:1.25 x 1.25 x .125

material:A‐36hot rolled steel

# required: 1

part # 29

2.5

2.5

0.251

0.2461.25

1.25

.125

.125

1.5.75

4824.001.5

7.5 7.5 7.5 7.5 7.5 7.5

.753.75 3.75 3.75 3.75 3.75 3.75


.75R

1.251.625

5.52.75

0.607.30


1.5.75


1.8561.856.928 .928

Grind/file 1/16" off of top edge.

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6730 X rail angle right

stock size:1.25 x 1.25 x .125

material:A‐36hot rolled steel

# required: 1

part # 30

7.57.57.57.57.57.5

1.5

1.125

3.5

6

48

2.732

5.5

1.856

1.856

1.8561.856

3.75 3.75 3.75 3.75 3.75 3.75

24.00

3.001.75

.5625.928 .928

2.75

1.375

.928

.928

.3125 DIA., 14 holes.

.3125 DIA.


1.50 DIA.

.75

0.375.1875

4.52.250.75.375

7.753.875

2.9961.50

.375 DIA.

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6831 X plate right



# required: 1

part # 31

7.57.57.57.57.57.5

1.5

48

3.75 3.75 3.75 3.75 3.75 3.75

24.00

.3125 DIA., 14 holes.

.75

0.375.1875

1.125

3.51.75

.5625

63.00

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6932 X plate left



# required: 1

part # 32

2.5

1.5.75

.3125 DIA.

1.25

0.75.375

0.75

1

.375

.50

0.75

0.312

.375

.156

#10‐32 threaded.

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7033 X belt pulley adjuster



# required: 1

part # 33

1.5

1.5

0.75

.75

.75

.37540

41.5

20.0020.75

1.5

1.5

0.75

.75

.75

.37520

21.5

10.0010.75

.3125 DIA., 2 holes (at ends).

.375 DIA., 25 holes,

.75 center to center.NOTE: these arelightening holes andare optional.

Radius both ends.

.3125 DIA., 2 holes (at ends).

.375 DIA., 12 holes,

.75 center to center.NOTE: these arelightening holes andare optional.

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7134 & 35 cable arms



# required: 1

part #s 34,35

PART # 34

PART # 35

ea.

0.755

1.5

1.5

0.75

.375

.75

2.50

0.75

.375

.375

.75

0.5.25

21.00

.3125 DIA.


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7236 cable arm mounting block



# required: 1

part # 36

0.625 0.625.3125 .3125

7.253.625

1/4 ‐20 threaded..3125 DIA.1/4 ‐ 20 threaded,.3125 CBORE to leave

.50" thread length.

0.75

1.5

.375

.75

21.001.50

1.125.5630.375

45° 45°

1.375

4.25

8.54.252.125

.688

.1875

0.75.37530°30°

3.51.75

R 2.419R 2.6251.3125 R 1.21 R

0.75.375

R 0.125.062 RR 0.5.25 R

2.0541.00

R 0.188.094R

for: RIDGID R2401

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7337 router mount Ridgid R2401



# required: 2

part # 37

for: RIDGID R2401

0.625 0.625.3125 .3125

7.253.625


0.75

1.5

.375

.75

1.5.751.5

0.875

.75

45° 45°

0.75.375

R 2.419R 2.6251.3125 R 1.21 R

R 0.125.062 R

.4375

2.51.25

1.7551.75 .875.875 2.50

8.54.25

R 0.25.125R

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7438 router clamp Ridgid R2401



# required: 2

part # 38

8.54.25

21.001.50

30°30°

3.51.75

4.252.125

1.125.563

1.375.688

0.875.4375

60°60°

2.0541.00

0.75.375

R 0.5.25 R

R 0.188.094R

0.625 0.625.3125 .3125

7.253.625


.50" thread length.0.75

1.5

.375

.75

0.75.375

R 0.125.062 R

for: BOSCH COLT

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7539 router mount Bosch Colt top



# required: 1

part # 39

8.54.25

21.001.50

30°30°

3.51.75

4.252.125

1.125.563

1.375.688

R 2.7761.388 R1.50 R

0.875.4375

45°45°

2.0541.00

0.75.375

R 0.5.25 R

R 0.188.094R

0.625 0.625.3125 .3125

7.253.625


.50" thread length.

0.75

1.5

.375

.75

0.75.375

R 0.125.062 R

for: BOSCH COLT

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7640 router mount Bosch Colt bottom



# required: 1

part # 40

R 2.7761.388 RR 31.50 R1.375.6875

1.5

2.5

.75

1.25

1.75 1.75.875.875

1.5.75

8.54.25

52.50

0.75.375

R 0.25

.125 R

0.625 0.625.3125 .3125

7.253.625


0.75

1.5

.375

.75

R 0.125.062 R

for: BOSCH COLT

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7741 router clamp Bosch Colt top



# required: 1

part # 41

R 2.7761.388 RR 31.50 R1.375.6875

1.5

2.5

.75

1.25

1.75 1.75.875.875

1.5.75

8.54.25

52.50

R 0.25

.125 R

0.625 0.625.3125 .3125

7.253.625


0.75

1.5

.375

.75

45°45°0.75.375

R 0.125.062 R

for: BOSCH COLT

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7842 router clamp Bosch Colt bottom



# required: 1

part # 42

2

2

0.375

1.25

0.5

1.125

0.75.375

1.00

.625.25

.625

.188

1.00

R 0.125.063R

1.5

1.25.625

.75

2.75

0.5

1.25

1.25

0.625

2.75

0.375

0.75

0.75

0.25

.625.313

.6251.375

1.375.375

.188

.125

.375

R 0.25.125R

.125R

2.5

0.625

1.25

2.5

0.5

0.375

0.375

0.375

0.75 1.5

1.5

.375

.188

.75

.1881.25.188

.25

.625

.313

1.25

.75R 0.27.125R

R 0.25.125R

.125 dia., 2 holes.

.125 dia., 2 holes.

.125 dia., 2 holes.

.25

R 0.188.093R

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7943, 44, 45 limit switch brackets

PART # 43X limit switch bracket(2) required

PART # 44Y limit switch bracket(2) required

PART # 45Z limit switch bracket(1) required



# required:as indicated

NOTE:All brackets are dimensioned forRadio Shack switch, part #275‐016.Use of other switches may requiremodification of bracket design.

NOTE:Stock size is listed as .1875 x 2.50,as these can be cut from theremaining material that is specifiedfor part #22 (Z cable plate.)

(F) top skin

PLYWOOD LAYOUT NOTES:

These are suggested layout of parts on 4' x 8'plywood sheets.

Allow for width of saw cuts.

Dashed lines indicate cuts to be made later.(A) bottom skin

(B) Y rib 1

(B) Y rib 1

(C) Y rib 2

(C) Y rib 2

(O) left inner skin

(M) rear plate

(H) vertical rib (H) vertical rib



(K) left top plate

(J) right top plate

(N) rear plate door

(Q) right skin

(L) left skin

(P) right inner skin

(D) X

rib 1

(E) X

rib 2

(D) X

rib 1

(E) X

rib 2

(I) right wall plate

(G) wall plate

(G) wall plate

(G) wall plate

(R) front plate

(E) X rib 2

(E) X rib 2

(E) X rib 2

4' x 8' sheet,3/4" finish sanded plywood,

such as "cabinet grade."

(U) cover side

(U) cover side

(W) cover rear

(T) cover top

(V) cover side filler

(V) cover side filler

(S) cover front

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80plywood sheet layouts

X 2

NOTE: All slots 3/4" nominal width,centered on dimension centerlines.Adjust actual slot width for light press fitwith measured thickness of rib material.

31

2626.00

31.00

23

2.5

2323.00

23.002.50

1.25

2.52.50

1.25

8.25 7.3757.3758.25

3

31

3

31.003.00 3.00

3 33.00 3.00

0.75

0.75

2626.00

0.75

0.75

.75

.75

.75

.75

31

2.5

31.002.50

6.5 6.375 6.375 6.5

1.875

29.5

1.25

2.5

29.50

6.50 6.375 6.375 6.501.875

2.50

1.25

1.8751.875

(A) bottom skin

(1) Required

(F) top skin

(1) Required

(B) Y rib 1

(2) Required

(D) X rib 1

(2) Required

(C) Y rib 2

(2) Required

(E) X rib 2

(5) Required

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81plywood parts A‐F

stock size:3/4" thickness

material:finish sandedplywood


NOTE:Cut opening for passthroughof wires in one rib. It does not needto be this exact size and shape.

24.5

33.00

24.50

8.5

3

8.50

3.00

24.5

2.75 2.625

2.438

3

2.752.625

25.25

1.688

25.25

3

3.00

3.00

2.50

2.6252.7524.50

1.688

0.188.1881.4981.50

0.179

2.447

3

1.498

2.438

25.25

3.00

2.50

2.6252.75

.188

25.25

26

14

26.00

14.00

31

3

25

3

31.00

25.003.00 3.00

4

6.75

2.5

13.25

4.00

2.50

6.7513.25

26.5

8.258.25

26.50

A

ASection A‐A

45°

1.5.75

2.438

1.50

1.50 DIA.

1.50 DIA.

(G) wall plate

(3) Required

(H) vertical rib

(6) Required

(i) right wall plate

(1) Required

(j) right top plate

(1) Required

(K) left top plate

(1) Required

(L) left skin

(1) Required

(M) rear plate

(1) Required

(N) rear plate door

(1) Required

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82plywood parts G‐N


as indicated# required:


Section A‐A

A

A

45°

1.5.75Typical pocket,enlarged detail.

2 2

8

4

2.001.001.00

4.00

pocket routed 5/8" deep

A

A

A

A

0.75

26

3 6.625

4

10

0.75

26

6.625 3

4

10

26.00

3.00 6.625.75

4.00

10.00

10.00

26.00.75

4.00

6.625 3.00

2

10

2

10

2

26

4.75

6.5

14

26.00

10.00 10.00

14.00

2.00 2.002.00

4.75

6.50

31

13.25

32533.00 25.00 3.00

10.75

2.52.50

10.75

13.25

31.00

(O) left inner skin

(1) Required

(P) right inner skin

(1) Required

(Q) right skin

(1) Required

(R) front plate

(1) Required

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83plywood parts O‐R




Section A‐A

45°1.5.75

S cover front

(1) Required

32.5

13

32.5

26.75

32.50

26.75

32.50

13.00

27

22.25

A A

AA

A

A27.00

22.25

R 1.5R 1.51.5 R 1.5 R

26

11.5

11.5

33.00

11.50

26.00

11.50

T cover top

(1) Required

W cover rear

(1) Required

U cover side

(2) Required

V cover side filler

(2) Required

NOTE:All dashed lines indicate cutsto be made later in theassembly sequence.

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84plywood parts S‐W




20

16

7.75

4

2

4.00

7.75

2.00

20.00

P1 cover window front

(1) Required

P2 cover window top

(1) Required

P3 cover window side

(2) Required

24

8

P3

P3

P1

P2

PLASTIC LAYOUT NOTES:

Below is a suggested layout of parts on24" X 24" polycarbonate sheet.

Leave space for width of saw cuts.

24" x 24" polycarbonate sheet.

R 22.00 R, typ.

R 22.00 R, typ.

R 0.75.75 R, typ.

16.00

8.00

24.00

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85cover plastic

stock size:.125" min.thickness

material:polycarbonatesheet


0.223

file/grind head of boltto leave approximately3/32" thicknessremaining.

3/32"

5/16 x 1 1/2" bolt

1.1735/8"

washer to fit 5/16 bolt.Outside diameters of washers may vary.Make sure outer diameter is larger thanthe outside diameter of the 22mmbearings. If it is not, use a washer with alarger outside diameter.

file inside diameter toapproximately 5/8"(8) modified bolts required

washer W1(6) modified washers required

1/4‐20 x 1/2"bolt

shorten bolt to approx.3/8" thread length.These attach the X rails tothe rail angles, and mayneed to be tested andadjusted for exact lengthrequired.

(14) modified bolts required

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86modified hardware

23

0.75

0.75

for y rib 1

for y rib 1

for x rib 1

for front plate

for rear plate

23.00centered onpanel width

.75

.75

29.529.50centered onpanel length

for x rib 1

1.5

6.256.25

1.50

equal equal 1212.00

2.25

3.53.5equal equal

2.25

S cover front

T cover top

A bottom skin

NOTE:Mark all red lines onto panels with apencil as indicated. See assemblydirections for more detailed descriptionof these marked lines.

Measure as indicated in drawings, and usepreviously cut plastic windows as templatesto trace. Trace lines tightly to window.

11.595

4.975

11.6

5.00

1.5

2.5

1.50

2.50U cover side

11.595

4.9755.00

11.6

1.5

2.5

1.50

2.50

U cover side

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87panel markups

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88wood fabrication

All of the wood parts can be fabricated with relatively simplewoodworking equipment. All of the basic cutting can beaccomplished with a circular saw, such as the one pictured tothe right. When combined with a straightedge fence which canbe clamped to the sheet material, it will be capable of just aboutall cutting needs in this project.

A table saw would be useful for cutting repetitive parts of thesame width, such as the inner ribs, to make it easier to keep theirdimensions consistent. However, with careful fence setup,these components can also be cut with a circular saw.

The few cuts that can't easily be done with a circular saw ortable saw can easily be done with a router. This project isdesigned to use a trim router, such as the one to the right,as the spindle. Purchasing the router at the beginning of theproject will allow it to be used to cut small cutouts andpockets that are found on several of the components, as wellas curved cuts.

Router mount drawings are provided for two models, theRidgid R2401 and the Bosch Colt. The mount design can bealtered and adapted for most similarly sized trim router.

The use of spiral up‐cut bits, rather than straight type bits, issuggested. These are similar in form to end mills used in amilling machine, but have flute angles and cutting anglesthat are specifically suited for wood. The increase in cuttingperformance over straight bits is well worth any additionalcost.

Both the circular saw and the router can be used with a fence toincrease their accuracy. Commercially produced fences withintegral clamps are available. Alternatively, a straight, rigid lengthof metal can also be used. Pictured to the right is a length of 1" x2"rectangular aluminum tubing and two C‐clamps to secure it inplace. With careful setup, very accurate cuts can beaccomplished.

Don't forget both hearing and eye protection. These are notoptional!

WOOD FABRICATION

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89wood fabrication

A few simple layout tools are required. A good qualityframing square, a triangle or machinist's square, tape measure,and a pencil. Make sure the square and triangle are actually at90 degrees. It may seem obvious that the legs would beexactly perpendicular, but low quality versions can be veryinaccurate. You can check accuracy by placing it along aknown straight edge and striking a perpendicular mark. Flipthe square or triangle 180 degrees and make another markparallel to the first. If it is in square, the lines will be exactlyparallel. If not, the lines will be closer together at one end orthe other. Note that this test is only as accurate as thestraightedge you are using.

When drilling holes in wood, a set of brad‐point drill bits isworth the investment. They cut a considerably cleaner hole thanregular twist bits, which are intended primarily for metal.

In addition to the tools shown, you will most likely need a fewother traditional hand tools, such as a hand‐saw, wood chisels,hammer, a nail set, etc.. An electric sander will also be helpfulin preparing the wood surfaces prior to painting.

Whatever selection of tools you end up using, what is mostimportant is accuracy of layout and cutting. Be careful to makeprecise measurements and thin, crisp pencil marks. Cut to thewaste side of the line, as seen in the photo to the right, tomaintain the desired dimensions of the finished pieces.

Okay, time to refer to the drawing sheets for the wood parts andstart cutting! Cut all of the wood parts on pages 80‐84 to theiroverall sizes.

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90wood fabrication

With all of the wood components cut to their overall sizes,there are several which have smaller specialty cuts.

The inner skin panels each contain two pockets. These shouldbe cut with the router, prior to cutting the 45 degree bevelalong the edges of the panels. Mark the locations of thepockets and set the depth of cut to about 1/8" less than thethickness of the material. Rout the pockets to within 1/8" ofthe marked lines.

After first removing material to within 1/8" of the markedlines, return for a finish pass that cuts right to the line.

The cuts shown to the right were done entirely by hand, butthe fence can be used to increase the straightness of the cuts.Exact size and precision of these pockets is not required, asthey are present only to provide wrench clearance whileservicing the machine.

After the pockets are routed, cut the 45 degree bevels on thetop edges, as seen in the image to the left. This can be doneeither on a table saw, or with a circular saw and fence.

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91wood fabrication

There round holes in several parts, such as the one markedin the image to the left. These cuts are best accomplishedwith a hole saw. Several of the metal components alsohave holes of the same size, so purchase of "bi‐metal" holesaws will allow cutting both materials. Two sizes of holesaws, 1 1/4" and 1 1/2”, will serve to cut all large roundholes in the project.

Drilling one or more holes tangent to the outside diameterof the final hole, as shown to the left, will provide space forchips to clear. This will make the sawing operation mucheasier. A hole at the center may also be pre‐drilled, to actas a pilot to align with the center drill that is integrated intothe hole saw.

Using the hole saw in a drill press at a low spindle speed issuggested, as well as using a piece of scrap wood as abackup board to avoid splinters on the back of the cut. Thefinished cut, and the plug that will need to be removed fromthe saw, should look like the image to the lower left.

As seen in the series of images to the right, severalcomponents have square holes in them. These can easily beaccomplished by drilling a series of holes with the hole sawto remove a bulk of the material. The router can then be usedto remove the remaining material.

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92wood fabrication

Many of the internal rib components contain notches, whichallow them to slide together with perpendicular ribs. Tomaintain consistency in location, these are best cut across allribs of the same type in one operation. This can beaccomplished with a circular saw as seen to the right.

Clamp and mark the cuts on the ribs. Measure the thicknessof the wood stock, and mark the cuts to correspond to thisthickness. Correct slot width will result in a small amount offorce being required to assemble the ribs.

Set the sawblade depth dimension to just over one half ofthe rib width. Carefully make a cut to the inside of each ofthe marked lines.

Make a series of closely spaced cuts to remove the rest of thematerial from the slot, as shown to the right.

These cuts can also be made on a tablesaw with a dado blade,or with a radial arm saw. The cuts could also be made with ahand saw, preferably in a miter box, and using a chisel toremove the waste material from the slot.

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93wood fabrication

As shown in the series of images to the left, one rib requires apass‐through to accommodate wiring for the electronics.Thus, its size is not crucial. The suggested size, indicated onthe drawings, leaves adequate material to allow nailing intothis piece.

This cut can also be made by removing a bulk of the materialwith a hole saw, and finishing with the router.

Cut the polycarbonate material for the cover windows, asshown in the image to the right. Leave the protective filmattached to the plastic while making the cuts.

If the polycarbonate being used is relatively thin, less thanabout 1/8", it may be carefully cut with a utility knife. It mayalso be cut with a circular saw and a standard fine‐tooth finishblade.

Regardless of method, use the fence to clamp the plastic sheetto a scrap sheet of wood while making the cuts.

The image to the right shows all of the wood componentsfor the base.

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94wood base assembly

On the bottom skin (part A), draw the pattern of lines that are shownin red in the diagram to the left. The lines are all spaced 3/4" apart.A more detailed drawing of these layout lines is shown on page 87.

Slide the X and Y ribs together as shown in the middle left photo.Drill 3/16" clearance holes as shown in the left photos, andgenerously countersink.

Place the assembled ribs onto the bottom skin as shown in the topright photo. The ends of the ribs should all fall along the drawnlayout lines as shown. With a pencil, mark around each rib onto thebottom skin, as shown to the right.

ASSEMBLY OF WOOD COMPONENTS

Remove the rib assembly from the bottom skin. The penciledrib outlines will be used as guides for glue application.

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As shown in the series of images to the left, apply carpenter'sglue to the area where the ribs meet the lower skin. Repositionthe ribs on the skin and attach with #10 x 3" wood screws. Usecaution that the assembly does not shift as the screws aretightened. The wet glue can act as a lubricant and allow thepieces to slide easily. Also be sure that none of the screw headsare proud of the top faces of the ribs, as they will interfere withlater placement of the top skin.

As seen in the lower left image, apply glue to the front edges ofthe ribs and to the lower skin as shown.

Position the two Y rib 1 (parts B) and clamp as shown to theright.

With clamp pressure applied, secure the two Y rib 1 parts to thelower skin with the #10 x 3" wood screws. Once fully secured tothe lower skin, attach with #6 finish nails into the endgrain ofthe X ribs, as indicated in the red circles to the right. Use a nailset if necessary, so that the heads are below the surface.

Using the same method and sequence of gluing, clamping,and nailing, attach the two X rib 1 parts as shown to theright. The base is now ready for attachment of the top skin.

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As shown in the image to the left, position the top skin on thebase. Offset the skin in each direction, and transfer thecenterlines of the ribs to top of the skin with pencil lines. Theselines will be used as a guide for fastening the top skin.

Remove the top skin, apply carpenter's glue to the tops of all ribs,and carefully position the skin. Using the lines as guides, nailthrough the skin and into the ribs with #6 finish nails. Theassembly should look like the lower left image.

As shown in the upper right image, apply glue to the end Y rib.Spread it so that it evenly coats the surface. Position the frontplate (part R), and secure with #6 finish nails into the rib. Thennail along the edges of the top and bottom skins into the frontplate, as shown in the right image.

Install the rear plate (part M) in the same manner. The baseassembly should now look like the image to the right.

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As shown in the image to the right, assemble the vertical ribs(parts H) to the lower wall plates (parts G.) Attach with #6finish nails and carpenter's glue. The center vertical rib iscentered along the length of the wall plate.

Prior to assembling, drill and countersink clearance holes forinstallation of #10 screws through the wall plates and outsidevertical ribs as shown.

Slide the assemblies down between the front and rear platesuntil they are in firm contact with the top skin of the base. Placea straightedge across the tops of the ribs as shown in the imageto the right. If they are not all exactly the same height, eithertrim the ones that are taller or shim the shorter ones asnecessary, so that their tops are parallel to the base. Measureup to the straightedge at several points to check this. Shims canbe made of paper or thin paperboard if necessary. The tops ofthe ribs need to be exactly the same height so that the top platewill be flat when installed.

When the alignment of the vertical ribs is satisfactory,remove the assemblies from the base. Apply and spreadglue to the mating surfaces, and reposition. Attach the lowerwall plate to the base with #10 x 1 1/4" wood screws. Withthe lower plates securely fastened, secure the vertical ribsto the front and rear plates with the #10 x 1 1/4" screws.

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Trial fit the top wall plates as shown in the image to the left. Ifthe plywood material is thinner than the full 3/4" that isspecified, the top of the plate may be slightly lower than the topedge of the front and/or rear plate, as seen to the left.

If the top plate exhibits this condition, trim the front/rear platesas shown in the lower left image. Apply glue to the matingsurfaces and install the top wall plates with #6 finish nails.

(Not pictured) With the side walls in place, the inner and outerskins (parts L, O, Q, and P)can be fastened to the base assemblywith 6d finish nails. Use the exploded view drawing on page 37as a guide. The top edges of the outer skins should be flush withthe top surfaces of the wall plates. The bottom edges of theinner skins should sit flush against the top skin.

Position the X plates (parts #31 and 32) on to the top of theircorresponding top wall plates (parts K and J.) Be sure thatthe correct ends of the X plates are facing forward. Align therear edges of the components so that they are flush. With apencil, trace the locations of the holes in the aluminum partsto the wood parts, as shown in the image to the right.

As shown to the right, drill a 1/8" pilot hole in the center ofeach hole location that was transferred.

Between and around this first series of holes, drill anotherseries of clearance holes for #10 wood screws. Countersinkthis second set of holes.

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Apply and spread glue to the mating surfaces, and fasten thetop plates (parts K and J) with #10 x 1 1/4” screws. The topplates are positioned exactly above the plates beneath them.The rear edge of the top plates should be flush with the rearsurface of the rear plate. This should leave one thickness ofplywood remaining at the front and sides of the machine, asseen in the image to the right.

The base is now complete, and should look like the image to theright. Sand any proud edges, set the nail heads below finishsurfaces, and fill heads with wood filler. The base can now beprimed and painted.

Measuring between the two top plates, as shown in the rightimage, the dimension should be 25.00", and be parallel fromfront to rear. If it is smaller than this dimension, the inside edge(s) of the top plates can be carefully trimmed with the routerand a guide or fence.

If the dimension measures slightly larger than 25" it can be leftas it is.

25.00"

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100cover assembly

Mark the window locations on the corresponding plywoodcover parts. Reference the drawing on page 87 fordimensions of these locations. Use the previously cutplastic window panels as templates, and trace aroundthem as shown to the left.

Draw a second series of lines, offset 3/8" to the inside of thewindow outlines, as shown to the right.

Using the router, remove material to the inside of the twolines. A hole saw can be used to remove large quantities ofmaterial close to the line. These cuts can be done freehand ifyou are comfortable to do so with the router. As they are notcritical for fit of other parts, any cutting error will only effectappearance.

Set the router cutting depth to 1/32" ‐ 1/16" greater than thethickness of the plastic window material. Rout this depth tothe pencil outline of the windows, to provide a rabbet for theinstallation of the plastic. While routing, check the fit of theplastic in the depression often.

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101cover assembly

When the rabbets have been cut for the installation of theplastic windows, assembly of the cover can begin. As seenin the image to the left, assemble the cover sides (parts U)to the filler pieces (parts V) with glue and nails.

Attach one of the side assemblies to the cover top (part T)as seen to the right. While nailing together, be careful notto place nails close to the angled pencil lines that extendup the sides and across the top. A saw cut will later bemade along this line. Keeping any nails at least 1.5” fromthis line will be a safe distance.

Attach the cover front (part S) to the assembly. Measureand mark a centerline on the front and top parts, so thatthe front will be centered when it is installed. Use care toensure that the top and side are as square as possiblewhen attaching the cover front. As seen in the upper rightphoto, a carefully scribed pencil line can be used as aguide to help to maintain squareness. Glue and nail thecover front to the top along its edge. Attach the side fillerto the front with screws from the rear. In the top rightimage, it can be seen that clearance holes for thesescrews have been pre‐drilled.

The rest of the cover assembly will use the machine baseas a working support, to ensure that the cover fits astightly as possible.

Stand the left side assembly in position on the base, asseen in the image to the right.

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102cover assembly

Place the assembled cover pieces onto the left side assembly,which is standing on the base, and fasten with glue, nails,and screws as were used on the right side. Check for correctalignment and squareness multiple times, before and duringattachment.

With the cover assembly still standing on the base, attach therear panel (part W.) Attach it to the edges of the coverassembly, but do not attach it to the base at this time.

As seen to the right, carefully measure and clamp a fence toallow cutting along the angle marks on the side pieces with acircular saw. Set the blade depth as deep as possible, to cutpartially into the cover top.

With both side cuts made, reposition the fence to cut acrossthe cover top. Setting the saw blade at a 30 degree tilt willallow it to align with the side cuts. Carefully position thefence so that the cuts will align at their ends. After cutting, thecover will now be in two pieces.

As seen to the upper left, mark and cut a shallow rabbet for thepiano hinge, using the router. Corners of the rabbet may need tobe cleaned out square with a wood chisel. Check the fit of thehinge as seen to the left. When the hinge is installed there shouldbe a gap between the two cover pieces that is the thickness of thecircular saw blade.

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103cover windows and hinge

Remove the cover from the base. The parts can now be sanded,finished, and painted.

It can be helpful to plan where wiring will be run for the machineelectronics before painting the base. As seen in the image to theright, two holes were cut with a hole saw for wiring to pass fromthe electronics compartment to the cable management arms. Ahole was also cut into the rear plate door (part N) for the routercord. The door will be installed during a later stage.

Place the two halves of the cover assembly on the base. With allof the edges of the cover sitting tightly to the base, there shouldbe a gap between the two halves that is equal to the thickness ofthe circular saw blade.

While maintaining this consistent gap, install the pianohinge to the two cover halves. The assembly should looklike the image to the left.

With the two halves connected via the hinge, install theplastic windows. Apply a thin bead of silicone adhesive inthe window rabbet. Spread it to an even thickness. Do notapply an excessive amount, as it will be pushed from thegroove and onto the surface of the plastic window, whichwill be unsightly. Remove any protective film from thewindows and carefully set the plastic into the adhesive.Press lightly to set. The installed windows should sitflush to the cover surfaces, as in the image to the right.

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104metal parts fabrication sequence

FABRICATING THE METAL PARTS:

The most efficient method of fabricating the metal parts is to do each type ofoperation all at once. More in‐depth descriptions of each step are on thefollowing pages. The following fabrication sequence was used here:

1. Cut all of the pieces to their overall lengths.If necessary, file the cut ends of the parts while holding them in a vise, to cleanthem up and make them as perpendicular as possible to the part.

2. Lay out all locations of holes and any secondary cuts with a marker andscribe.

3. Center punch all of the holes.Use a spring loaded centerpunch for accuracy and speed.

4. Drill all holes.It may be quickest to drill all of each size hole at once. Keep the same size drillbit chucked in the drill press and drill all holes of that size in all of the partsbefore changing bits. It may be faster to clamp and unclamp parts in the drillpress vice than to constantly change drill bit size while working on only one partat a time.

5. Drill counterbores.Here it may be easiest to drill the primary hole, keep the part clamped, changethe bit, and then drill the counterbore. This will maintain concentricity.

6. Tap all threaded holes.

7. “Cut” the large and complex part shapes, such as the router mounts, bystitch drilling a series of closely spaced holes to nibble through the material.Use a hand file to finish the parts.

8. Fabricate the studs.Referencing the stud schedule on page 29, cut all of the steel studs to lengthfrom threaded rod. File the ends flat, with a chamfer around the edge.Threading a nut onto the rod before cutting can help straighten any threaddeformation as it is removed. However, this method should be unnecessary iffinish filing is done properly.Keep the finished studs organized by size.

9. Fabricate the modified hardware.Referencing the drawings on page 86, modify the bolts and washers asindicated. These modifications can all be done with a hand file. Keep thesefinished parts organized as well.

Metal Fabrication Sequence

1. Cut Lengths

2. Hole Layout

3. Centerpunch Holes

4. Drill Holes

5. Counterbore

6. Tap Holes

7. Plate Cuts

8. Studs

9. Hardware

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105clamping tools

METAL FABRICATION

Most vises have jaw faces that are serrated. Using these toclamp aluminum parts can badly mar the finish surface.The solution is to buy or fabricate a set of jaw covers. Thereare commercial versions available in many types of non‐marring materials: brass, plastic, rubber, etc. The images tothe right illustrate a set of covers that were quickly fabricatedfrom a piece of common aluminum roofing flashing.

Taking some measurements from the vise, transfer thisinformation to a paper pattern. The covers should wrappart way around the jaws to hold themselves in place. Itmay take a couple of adjustments to arrive at a pattern thatwill fit well. A sheet of card stock/ cover stock, or otherthick paper material will be durable as a pattern.

Transfer the pattern to the aluminum sheet with a finetipped marker. The aluminum can be cut by scoring with autility knife blade and then lightly bending it back andforth. It will snap off cleanly along the score mark. Thematerial is thin enough that curves and inside corners canbe cut this way.

Wrap the cover as tightly as possible around the vise jaws.It is OK if they are slightly loose. This type of aluminum isvery thin, and will wear out after some use, so keep thepattern to make more covers in the future.

Another helpful clamping device is a block to hold roundstock, such as threaded rod, in the vise. These were quicklyfabricated out of two lengths of 3/4" square oak stock.They were clamped together with a strip of paper mat‐boardbetween them as a spacer (cardboard or a thin strip ofwood would work fine). Drill a series of holes in commonsizes. These are very helpful when making studs fromthreaded rod. They work wonderfully to hold them withoutdamaging the threads, such as while filing their ends flat, asin the photo to the left.

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106scribing & cutting stock

The tools to the left were used to mark the locations of cutson the lengths of material. These are a steel engineer's scalewith 1/64" divisions, a felt tip marker, a carpenters awl, and asmall square. To measure pieces longer than the 6" scale, a24" carpenters square was used, hooked over the end of thematerial. The marker is used to provide a colored backgroundto scribe through. A blue marker may work better than a blackone, as it may provide better contrast when a line is scribedthrough it. Blue is also the color of the traditionalmachinist’s dye that is used for this operation.

Mark the area where the cut is to be located with the felt tipmarker. The scratch awl is used for just that‐ to scratch a thin,accurate line through the area of color. The scribed lineshould not go deep into the material, just enough to gothrough the marker. If the marker is washed off, the scribedline should just barely be visible, and barely be felt with afingernail.

Use the square to extend the scribed line all the way aroundthe material. The end of the last line should meet up exactlywith the first line. This will serve as a check that the marks areprecisely perpendicular to the edges.

With the piece clamped in the vise, begin cutting with ahacksaw. Note that the cut is just to the side of the scribedline. It just barely leaves the scribed line on the finishedpiece. Use the edge of your finger as a guide for the blade, andbegin to cut carefully and slowly. Keep the blade horizontaland only apply pressure on the forward stroke. After cuttingabout 1/8"‐3/16" deep, remove the piece, rotate it 90 degreesand make another cut on this face, also about 1/8" ‐ 3/16"deep. Continue this all the way around the perimeter of thepart, as seen to the lower left.

Like the scribing, the last cut should exactly line up withwhere you began. With a consistent 1/8" ‐3/16" groove allthe way around the part, make a final cut all the way through.The groove will help guide the blade straight through thematerial on the final cut. The completed cut should now beperpendicular to length of the material and require minimalclean‐up with a file.

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107cutting stock with a miter saw

While perfectly adequate cuts can be made with a simplehacksaw, the method is tedious. The large number of partson this machine can by cut much more quickly andaccurately with a simple power miter saw, as shown in theimage to the left.

A common fine‐toothed carbide tipped blade designed forwood can be used, however, a much finer finish can beachieved with a blade designed specifically for use inaluminum. These blades have a negative cutting rake angle.The difference in cut quality between a wood blade and analuminum blade can be seen in the image to the right. Thepart to the rear was cut with the aluminum blade.

The blade used here is was made by Onsrud, and waspurchased directly through the manufacturer via their ebaystorefront. Best performance with this type of blade can beachieved with a blade lubricant, such as the wax stick in theimage to the right. Carefully lower the spinning blade ontothe wax stick prior to making a cut, to coat its teeth.

When making a cut, be sure that the work is securelyclamped to the saw. Pull the saw trigger and allow theblade to come to full speed. The blade used here is quiteheavy, and its quickly accelerating mass will move the sawsignificantly if it is not clamped securely to a surface.Gently lower the blade into and through the work piece.Release the trigger and allow the blade to come to a fullstop BEFORE raising it back up through the cut part. Thiswill greatly minimize the chance of kickback or having theblade catch an edge of the part.

ONLY use this method if you are comfortable with theequipment. Wear full safety gear and never place any part ofyour body directly in line with the spinning blade.

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108labeling parts

The aluminum parts can all be cut either by hand orwith a miter saw. It is recommended to cut the cut thesteel parts to length with a hacksaw, or other coldmethod such as a metal cutting bandsaw withcoolant. Do not use any method that will introducesignificant heat, such as abrasive cutting blades, asheat may cause small warping of the material.

Cut all of the aluminum and steel parts to length. Tostay organized, as each part is cut to length write thedimension of its length on it with a marker. It is alsohelpful to write the part number or name.

After all of the metal parts are cut to rough length, file theends clean if necessary. Clamp the piece in the vise withthe end face up, using the soft jaw covers, and carefullyfile the end faces flat. Be careful to keep the filehorizontal, and only file deep enough to get below themarks from the saw blade. It is better to err on having apart slightly too long than too short, so be sure not to filetoo far even if it means leaving an end face with some finesaw marks remaining. File a slight chamfer on each endface edge to remove any sharp burrs.

Keep the parts organized. There will be a lot ofparts in total, so keep organized with some sort ofsystem, so that pieces don't become mixed up.

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109hole layout

To mark the locations of the holes to be drilled on the parts, a6" engineers scale, felt tip marker, circle template, the scratchawl, and a fine tip felt pen were used. A disposable technicalpen in an .03 tip width works well. A carpenters square can beused on the longer parts. It ensures that measurements areaccurately made from the end face. Be cautious if using acarpenters square. While some edges are marked in traditional1/8", 1/16" or 1/32" divisions, others may be marked in1/10" or 1/12". This can cause serious errors in marking if notcareful.

Use the felt‐tip marker to color a zone on the part where thecenter line of the hole is located. Measure and scribe a fine lineacross the part at the center of the hole location. Also scribe aline at the side to side distance to create a scribed crosshairs ateach hole location. Scribing the line that runs parallel to thelength of the aluminum parts may be difficult due to marks inthe surface from the extrusion process. These might pull theawl into them and create an inaccurate line. If this happens,color back over any inaccurate scribe lines and try re‐scribing.Use the circle template, lined up to the scribed crosshairs, todraw the outline of the hole with the fine felt‐tip pen. Also,write the diameter of the hole directly on the part to avoidhaving to consult the drawings later to re‐determine the holesize. With everything clearly marked on the part, little thinkingwill be required when drilling the holes. Mark the tapped holesin a similar manner.

A drill press is highly recommended to achieve the necessaryaccuracy when drilling holes. It is almost indispensable, andthey can be purchased quite inexpensively. Make sure it hasenough quill travel and throat clearance to handle all of thedrilling requirements. A drill press vise of some sort is alsovery helpful. The drill press used here was a very inexpensivehomeowners quality, equipped with a compound cross slidevise. Take some time to adjust the drill press so that the tableis exactly perpendicular to the quill.

When drilling, especially on the aluminum parts, always use aproper cutting fluid. Drilling aluminum dry will quickly destroythe drill bit.

The drill bit itself can be used to accurately clamp the part.Extend the quill down alongside the part. Push it up againstthe drill bit while clamping it in place. This will ensure that itis parallel to the length of the bit and quill travel.

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110tapping holes

Clamp the parts to be tapped firmly in a vise (use the softjaw covers, unlike what is shown here). Secure the tap intothe tap handle and start it into the hole. Be sure to useplenty of tapping fluid that is designed for tappingaluminum. WD‐40 can be used if it is not available. Usingtapping fluid is crucial. Taps will not last long whentapping aluminum without it, especially the smaller sizes,possibly not even making it through the first hole.

If you have never tapped a hole before, it is highly suggestedto do a trial run on an extra piece of aluminum. Use theproperly sized drill bit and drill a few holes to be tapped1/4‐20. It is worth getting used to the experience on ascrap piece, as taps can be quite fragile. Any side loadingcan immediately snap them off, as can excessive chiploading in the flutes. A broken tap can be nearlyimpossible to remove from the part without specializedequipment, so a tap broken off in a final part will mostlikely require starting completely over with a new piece.Better to break a tap in a piece of scrap. That said, with theproper technique and a good lubricant, tapping holes inaluminum is quick and easy. Also recommended istapping all of the 1/4‐20 holes first, to get comfortable withthe technique, before attempting the 10‐32 holes. Thesmaller tap size is less forgiving of error and will breakmuch easier.

Turn the tap into the hole and check the alignment as itstarts to bite. Look at the tap from both the front and theside to make sure it is exactly perpendicularly to the part.The only opportunity to make any correction is during thisfirst partial turn of the tap. Even then, the amount ofcorrection possible is minor. Taps are very brittle andcannot withstand ANY side loading. As the tap is threadedinto the hole, stop every turn or so and back the tap out apartial turn to break the chips before going deeper.

When the tap comes out of the backside of the hole, cleanthe chips off of it with a spray lubricant before threading itback out of the hole.

With the tap removed, clean it thoroughly of all chipsbefore starting the next hole.

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111stitch drilling

There are a few large diameter holes that need to be cut, aswell as some unique shapes cut from plate. While the largediameter holes can be cut with a hole saw if it is available, thefollowing technique, called stitch drilling, can be used for anyof these cuts. A series of closely spaced holes, that slightlyoverlap, are drilled along the edge of the cut line. This willremove a plug of material. Final shaping can then be donewith a hand file. This can be used both for parts cut from thin(3/16") stock, as well as out of considerably thicker plate.

The best diameter of drill bit to use for this is a compromise,and will require some judgment. The smaller diameter drill bitused, the less material that will need to be removed with thefile during clean‐up. However, the smaller the diameter the bit,the more difficult it is to drill sequential holes that barelyoverlap. A larger diameter bit makes it much easier toaccomplish this overlap, but requires more material removalwith the file, hence requiring more time. Generally, thesmallest bit that will easily allow drilling holes that overlap theprevious ones should be used. A bit around 1/4" dia. willprovide a good starting point. If in doubt, use a larger bit.

Clamp the part in a vise and finish file to the final size.

In the example to the right, a large round hole is being cut. Acircle template was used to draw a concentric circle that issmaller in diameter than the desired hole by the diameter ofthe drill bit being using. For example: for a 1.5" dia. finish holesize, using a 1/4" drill bit, a 1.25" circle was drawn. A series ofslightly overlapping 1/4" holes were then drawn using the circletemple, placing their center points on the inner circle. Thesewere simply spaced by eye. The center point of each 1/4" holewas center punched. The holes were drilled, removing a plug ofmaterial as shown. The same process can be used for thickerstock, as seen in the images to the left. Both parts were finishedto final size by hand filing. If the holes do not completelyoverlap, it may be difficult to remove the waste material. A coldchisel may be used to cut any remaining webs. The waste on thepart to the left was cut off with a hacksaw.

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112hole saw

There are several wood components with large holes, which areeasiest to cut with a hole saw. Use of the hole saw is discussedon page 91. Likewise, there are several aluminum componentswhich may also be cut using the same two sizes of hole saws (11/4" and 1 1/2".) Use of a hole saw will be especially helpfulwhen fabricating the Z motor mounts. These two parts have aconcave radius groove cut out of their inner faces, which caneasily be cut with the 1 1/4" hole saw. The saw must be of thetype that can be used to cut metal.

The easiest way to accomplish this cut is by clamping the twoparts together, with a 3/4" spacer between them, and drilling asone unit. In the top two images, the parts are clamped in a benchvise to measure and mark the hole location.

As when using the hole saw in wood, pre‐drilling smaller holesfor chip clearance will improve the smoothness of the cut.Drill these holes just to the inside of the larger hole that willbe cut. An additional hole can be drilled at the center, to actas a guide for the pilot drill in the center of the hole saw. Thisis optional, and was not done here.

Clamp the work in the drill press vise and carefully align thehole saw to the marked circle. Use a low spindle speed on thedrill press. Use a cutting fluid or WD‐40 while making the cut.

The completed parts with neatly matched grooves areshown to the right. No further finishing was required.

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113carriage match drilling

The carriage assembly has several parts that require holesdrilled while they are clamped in alignment with eachother. Gather the following five parts together, as seen inthe image to the left:

#13‐ carriage block rear lower#16‐ carriage block front right#17‐ carriage block front left#19‐ lower spacers

Begin with lower rear block, one lower spacer, and either ofthe front blocks. As seen in the top and middle images tothe right, using an accurate square, scribe guide lines thatcorrespond to where the edges of the spacers will be whenthe parts are assembled. Clamp the 3 parts together with a5/16” bolt, as seen in the lower left image. Use the scribedlines as guides to keep the front and lower blocks square toeach other, and centered properly. Double check that theyare square to each other and fully tighten the bolts. Triplecheck that left and lower blocks are square to each other.

Flip the assembly over and clamp it into a vise on the drillpress table. Check again that the parts are square to eachother. Insert a 3/16” drill bit into the chuck. Lower the quillnext to the parts to make sure that the drill press spindle isparallel to the edges of the parts. This drilling operation willbe going through the thickness of all 3 parts, so the drill needsto go as straight through them as possible. Carefully align thedrill bit with the existing holes of the lower carriage block anddrill down through the other two parts. Align the bit carefullyso that the existing holes are not reamed out larger.

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114carriage roll pins

Take the parts out of the vise and disassemble them. Markthem first so that they can be put back together with thespacer in the exact same orientation. Carefully clean theparts of any oils, cutting fluids, etc.. With a hammer, drivetwo 3/16” x 2” roll pins down through the 3 parts to re‐assemble. With no bolt, the joint connection between theparts should have no perceptible play or movement.

Repeat the procedure with the right side parts. Foraccurate alignment, use the square as well as takingmultiple measurements between the left and right sidecarriage blocks to make sure they are exactly parallel.This distance should measure 2.625".

Drive the roll pins down through the second joint, as seen inthe image to the left. With no bolts installed, as seen to theright, the assembly should be strong and rigid, with noplay. The 5/16" bolts will be reinstalled during a laterassembly step, to give additional strength to the joints.

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115cutting router mounts

The router clamps are fabricated from thick aluminum barstock, and have a complex series of curved cuts. While a metalcutting bandsaw would be a helpful tool to make these cuts, thepieces here were made using the stitch drilling techniqueoutlined on page 111. The basic principle is the same: drilling aclosely spaced series of holes and then hand filing to final size.Due to the thickness of the material, it is beneficial to use thesmallest practical size of drill bit diameter, as a larger bit willleave more material to be removed across the face of the partthickness. A 1/4” drill bit was used in these photos.

As the geometry of the parts is relatively complex, it may behelpful to print the drawing sheets and cut them out for use aspatterns. If printing patterns, use durable heavy paper or cardstock. After printing, measure the longer dimensions to checkthat the sheet has accurately printed to scale. If not, adjust theprinter scale setting. Unfortunately, printer scale error is oftenless than 1%, which is enough to cause a slight inaccuracy butnot enough to be able to correct through the printer driver.Carefully cut the pattern out with a sharp razor blade.

The parts shown here were laid out directly on the stock,without aid of paper patterns. The matching components(mount and clamp) were marked together as one unit. To do so,a wood block of the correct thickness was clamped betweenthem. Fillet curves were marked with a circle template and finefelt tip pen. As seen in the image to the left, these were the firstholes to be drilled in the stock. After drilling these holes, theclosely spaced stitch holes were placed along the rest of thepart outline, as seen in the image to the right.

A hacksaw was used to remove the excess material. On themount component, a hole saw was used to drill close to thesurfaces that will contact the router body. This can be seen inthe image to the right. While the hole saw is a smallerdiameter than the router body, it can cut much closer to thelayout line, and will require less filing than a series of smalldiameter stitch holes. After removing the bulk of the stock, asseen in these photos, the parts were hand filed to remove theremaining material.

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116belt clamps

The drive belts are secured with fabricated clamps that havecorresponding grooves cut into them. This can be achievedwith a simple hacksaw and some patience. No filing was donein any of these photos, this was all done with just thehacksaw.

Hold a length of the belt securely on the piece of stock to bemarked. Scribe short marks that align with the width of theroot of the belt teeth. As you move along the belt markingteeth, move your head as well. It is important that you arelooking exactly straight‐on at the belt while marking to avoidparallax error.

With the teeth widths marked, use a square to extend thescribe lines across the width of the stock. With the stockfirmly clamped in the vise, slowly begin to use the hacksaw tocut out the grooves. Keep the saw as horizontal as possibleand use a finger or two as a guide against which the side ofthe blade rests. Think of the saw blade as a long narrow file.Tilt the saw to the side to widen the slot if necessary.Alternatively, install two blades in the hacksaw handle. Thiswill effectively create a wider blade that may more closelymatch the width of the grooves.

When the belt is installed on the machine, these parts areexerting clamping force against the belt, therefore the depthof the grooves do not need to be the full tooth thickness.More important is that the center to center spacing of thegrooves matches the belt. As long as there is some smallamount of groove it will prevent any belt slippage onceclamped together. Cutting these grooves is much easier thanit may seem, and the work progresses quickly.

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117installing studs‐ Assembly

With all of the 1/4” threaded studs cut to length, gather all ofthe metal parts together. Locate all of the parts that will havestuds threaded into them. Make sure that the threads on allthe parts are clean and free of any oils, tapping fluids, etc.Clean the parts with a degreaser if necessary. Cotton swabscan be used to reach into the holes.

The studs will be adhered into their holes with a thread‐lockingcompound so that they will not turn when nuts are tightenedonto them. Since it can be very difficult to remove these studsonce they are bonded in place, it is highly advisable to do a trialassembly of all parts that are held together with studs. Thiswill allow checking that all stud lengths are correct. Using plainnuts can help with a trial assembly, as using the nylon‐insertlock nuts will simply cause the stud to turn deeper into thepart. Following the exploded‐view drawings on pages 30‐33,thread the correct studs into the parts. The stud lengths arecalculated for 1/2" thread engagement into the parts. With allof the studs temporarily in place, follow the relevant directionson the following pages to complete a trial assembly of matingparts. If all seems to assemble together correctly, disassemblethe parts, keeping stud lengths organized.

Apply a couple of drops of “permanent” thread‐lockingcompound to the end of the stud. A small amount issufficient. The tip of the tube can be used to spread thecompound around the circumference of the stud. Thread thestud into the hole to the required depth. Set the parts asideto let them cure. Leave them undisturbed for a full day beforebeginning any assembly.

If any of the studs need to be removed, the permanentthread‐locking compound requires the application of heat tosoften it. Heat the part in an oven at 400 degrees F, or use apropane torch applied to the part. The stud should now beable to removed with a pair of locking pliers. After cooling,chase the threads in the aluminum part with a tap to removethread‐locking compound residue before installing a new stud.

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118gantry rail‐ Assembly

Begin assembly of the metal parts by attaching the Y rail (part #11) to the gantry tube (part #02). Assemble using (7) 1/4‐20 x1/2"socket head cap screws and lock‐washers. The cap screwsneed to have full thread engagement in the rail, yet notprotrude beyond its outer face or they may strike the carriageas it slides. Achieving this proper engagement may requiringadjustment by stacking several lock‐washers together. Here,two were used under the head of each screw.

Use a hex key that is long enough to feed the cap screwsthrough the 1/2" holes in the back face of the gantry tube.It may be easier to do this if the front of the gantry tube isoriented facing up. This way, gravity is holding the capscrew on the hex key as it is fed up through the holes.

Get all 7 of the screws threaded into the rail, but do nottighten fully. Tighten the two outer ones until they are justsnug enough that the rail can still be moved around whenpressure is applied. Check to make sure the threads do notprotrude beyond the face of the rail.

Use a scale and measure both top and bottom, and at each endof the rail to make sure it is exactly centered on the gantrytube. When it is centered, tighten all of the screws downfully. As seen in the image to the left, the gantry tube shouldextend beyond the rail at each end by .75".

Washers

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119left gantry‐ Assembly

As per the diagram to the left, and image to the right:

Thread a nylon insert lock‐nut, with two flat washers above it,onto each of the studs in part #03, marked “gantry left top”.Thread the nuts nearly to the top, leaving about 3/16" of an inchbetween the washer and the part. Thread another nut onto eachstud, this time with the nylon insert going on first. To do this, ifmay be necessary to thread the nuts on in the conventionaldirection first, perhaps even a couple of times, so that the studforms threads into the nylon insert. Even having done this, itmay be difficult to get the nuts threaded on straight. Use cautionand do not force the nut onto the stud if it is not going onstraight. Thread these nuts up the stud so that they are about1/2" below the first set. Slide a flat washer up each stud so thatit is against the inverted nuts.

This assembly should now slide into the slots on the leftside of the gantry, and look like the image to the right.Make sure that the correct end of the part is facing forward.Depending on the type of washers being used, and theirparticular outside diameter, it may be necessary to file a flaton the four washers that are inside the gantry tube, as seenin the top right image. SAE dimension washers should fitwithout modification. USS dimension washers are larger indiameter.

Using a square, align the inserted part so that it is perpendicular tothe gantry and tight against the end of the Y rail. Tighten the topset of nuts, being careful to keep everything perpendicular.

Next, thread the inverted nuts back down the stud so that they arejust putting a very light pressure against the bottom inside face ofthe gantry tube. The purpose of these nuts is to keep the gantrytube from being crushed under the pressure of tightening thebottom part.

With the lower nuts in contact with the inside of the gantry tube,slide two washers and part # 01 (gantry bottom), up the studs.

Washers

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120right gantry‐ Assembly

WASHERS

Using the square to make sure part #01 (gantry bottom) is alsoperpendicular to the gantry, install another set of flat washers andlock‐nuts to hold it in place. Tighten securely. The assemblyshould look like the image to the left. Note the drawings andimages carefully for the placement of the four washers betweenthe gantry tube and the other parts. These are necessary forcorrect spacing.

Using the same procedure, and sequence of nuts and washers,install parts #01 (gantry bottom) and #04 (gantry right top) on theright end of the gantry tube. Parts #05 (gantry spacer) and #06(gantry outer right) will be installed next. Before installation ofparts #5 and 6, thread two 10‐32 x .75 setscrews into the holes asseen in the image to the right.

Note that part #06 (gantry outer right) is not quitesymmetrical and it is possible to accidentally install it upsidedown. When installed in the correct orientation, the verticalhole at each end should align exactly across to a similar set ofholes in part #04. With these parts in the correct orientation,install washers and nuts onto the studs and tighten to securethem. All three of the top parts should be flush across theirtop faces.

The gantry assembly should look like the image to the left.Next install parts # 07 and #08 (Y motor mounts) as shownto the right. Note that these parts are different. The holesfor the motor attachment are offest to the inside. Closelylook at the image and the exploded‐view drawing to notewhich side they face. If in doubt, hold a motor up to themounts to make sure the holes align.

Install a washer and nut on each motor mount stud. Do nottighten then down fully. Tighten the nuts just to the pointwhere the mounts can be moved around by hand.

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121carriage blocks‐ Assembly

Locate the carriage parts as seen in the image to the right. Theyare parts:

#12‐ carriage block rear upper#18‐ upper spacersthe sub‐assembly from page 113 (parts #13, #16, #17, #19)(4) 5/16”x 3” grade 8 bolts, nuts, and washers.

Begin with the sub‐assembly that is currently held togetheronly with roll pins. As seen in the image to the right, installtwo bolts, with washers and nuts. Use lock‐washers if the nutsare not lock‐nuts.

Install the upper rear carriage block (part #12) and the twoupper spacers (part #18) as seen in the image to the left.With the nuts lightly snug, measure between each end ofparts #12 and #13 to ensure that they are exactly parallel.This distance should measure 2.625". Adjust as necessary.When satisfied that they are parallel, tighten the top twobolts fully. If a torque wrench is available, tighten all fourbolts to 25 lb/ft. Double check parallel alignment to ensureparts have not moved during tightening.

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122carriage assembly

Organize the four bearing blocks to be attached to thecarriage assembly. Note that one (part #15) has a studinstalled for later installation of the Y belt clamp. Thisbearing block is installed in the top position. The otherthree bearing blocks (part #14) are identical.

Using the exploded‐view drawing on page 31, and theimages on this page, install the four bearing blocks in theircorrect orientations.

Next, install the Z motor mounts (parts #20 and #21) as shown inthe images to the left and right. Use a square to position themperpendicular to the carriage. Take care to set them as squareas possible, as any error will later cause misalignment of the Zaxis leadscrew. Note that the nuts are very close together, andthis may prohibit use of washers. They are also close enoughtogether that tightening the first nut so its flat is facing thesecond nut will give more working space for a wrench.

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123Z axis rail assembly

Locate the Z axis parts as seen in the image to the right. Theyare parts:

#24‐ z rail#25‐ z rail block#26‐ nut plate block

Assemble the parts together as seen to the right. Installnuts on the top and bottom studs of the Z rail. Do nottighten the nuts holding the nut plate block at this time.With the top and bottom nuts lightly snug, adjust the Z railblock so that it is exactly centered on the width of the Z rail.Take multiple measurements on each side, and top andbottom. When centered, tighten the two outer nuts.

Thread the nuts holding the nut plate block so that they arenot quite snug against it.

10‐32 set screw

5/16 lock nutwasherbearing

5/16‐18 x 1 1/2" bolt

Note that in some locationsthis bolt has a modified head.

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124bearing installation

The next step is to populate the gantry and carriage withbearings. Most of the bearings are attached in theconfiguration of bolt, bearing, washers, and nut that is showin the above left diagram. This sequence of parts is alsoseen in the images to the right.

As each bearing is installed, thread the lock‐nut on farenough that there is just a very small amount of clearancebetween the washers and the part. The bearing should justbe able to slide slightly along the face of the part, but notrock or feel loose.

NOTE: In addition to this series of photos,refer to the exploded drawing on page 32that depicts the bearing locations. It issometimes difficult to have one view clearlyshow all of the bearing locations in a givenstep, so this drawing may help to clarify.

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125gantry bearings

Begin by installing the four bearings in the left end of thegantry, that are shown in the images to the left and right.

Note that the lower bearings use bolts with modified headsfor clearance. These are circled in the image to the right.

The left end of the gantry also uses two bearings as an idlerbearing for the belt drive. These can also be installed duringthis step. Use a 5/16‐18 x 2.5" long hex head bolt or sockethead cap screw. Two fender washers are used as flanges,and a short stack of standard flat washers are used asspacers, to achieve the correct height. When installed, theunderside of the top fender washer should be 1" from thetop face of the upper gantry block.

The right end of the gantry uses four bearings installed in thesame positions as the left end. In addition, there are fourmore bearings positioned from the underside, as seen in theleft image. The right end of the gantry has a total of eightbearings installed.

The lower bearings on the right end of the gantry also usebolts with modified heads. They are circled in the image tothe left.

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126carriage bearings

At the location of each of the bearings that has beeninstalled on the carriage, thread a setscrew into the holethat is perpendicular to it. For now, just thread these in afew turns, so that they do not fall out.

The four bearing blocks (parts # 14 and 15) have a longerbolt that goes through them, holding a bearing on eitherside of the aluminum block. The bearing assemblysequence is seen in the image to the left. Slide one bearingonto the socket head cap screw, and then one washer. Notethat there is no washer between the head of the sockethead cap screw (5/16‐18 x 3") and the bearing. Insert thisthrough the bearing block. Next slide a washer, bearing,another washer, and then the lock‐nut.

Install all of the bearings onto the carriage assembly. Study theimages on this page, and the illustration on page 32, for thepositions of all bearings. This step will be installing a total of24 bearings on the carriage assembly.

Note that four bearing locations require the use of modifiedbolts with thinned heads. Two of these are circled in red in thelower right photo. The other two are obscured in these photos,but are in the same positions on the other side of the carriage.

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127carriage installation on gantry

Measure the outside distance of the lower gantry blocks, asseen in the left and right images. It should measure 24".The dimension can be adjusted by repositioning thecomponents on either end. Bringing them closer togethermay require trimming the length of the Y rail slightly.Before making any adjustments, consult the measurementof the base that was taken on page 99. For the best fit, thegantry measurement take here should be exactly 1" lessthan the measurement of the base taken on page 99.

After assuring that the correct 1" difference between thetwo measurements can be achieved, remove thecomponents from the left end of the gantry. Fully removethe lower piece. Slightly loosen the remaining nuts, andthe assembly will slide out of the slots in the gantry tube.

Slide the carriage assembly onto the gantry, feeding the Y railbetween the bearings. There should be enough clearancebetween the bearings and the rail that it slides on easily. Ifthe bearings do not move far enough apart to allow thecarriage to slide onto the rail, stop and investigate why. Ifthere was inaccuracy in drilling holes, there may not be theproper range of adjustability for the bearings. If this happens,look closely to determine which bearings need to be able toslide further away from the rail. Remove them from thecarriage assembly. The holes can then carefully be filed toelongate them, giving more adjustment range.

Re‐install the components on the left end of the gantry. Use asquare to ensure they are perpendicular to the gantry, andremeasure the dimension taken at the top of this page.

Be careful in handling the final gantry assembly, as thecarriage will slide very easily and has significant mass, whichcan easily lead to smashed fingers.

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128gantry belt drive

As seen in the images to the left and right, install a 10 toothtiming belt pulley onto the shaft of a stepper motor. Ameasurement of 7/8" from the face of the motor to theouter pulley flange should result in a correct belt alignment.

Install the motor with four 10‐32 x 1" socket head capscrews, or machine screws. Place washers between themotor mounts and the motor, as shown to the left, to raisethe round boss on the end of the motor clear of the mounts.Two flat washers were sufficient here for clearance.Tighten the motor to the motor mounts.

Hook the 250 tooth belt around the left idler pulley. Removethe motor, still attached to the mounts, from the gantry andhook the other end of the belt around the motor pulley. Themotor and mounts can now be lowered back down intoposition, and the nuts re‐installed on the mount studs.

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129gantry belt drive

Tighten the nuts on the motor mount studs so that theyare not quite snug. Insert a hex key through the holes asshown in the image to the right, so that it engages with thesetscrews. Tighten the setscrews, working alternately fromone to the other, to tension the belt.

When the belt is at sufficient tension, fully tighten the nutson the mount studs. Be careful to not overtighten the belt,as the setscrews are capable of applying significant pressure.

Install the Y belt clamp as shown in the image to the right.Before tightening, it is important to install a small spacerbehind the top side of the clamp. This serves to help theclamp put even pressure against the full width of the belt.The spacer is circled in red. The spacer used here was cutfrom paper mat‐board and measures slightly more than1/16" thick.

Note that the clearance between the stud and the insideof the belt is very close. If contact with the belt occurs,especially at the motor end of carriage travel, it may benecessary to shorten the stud slightly. Depending ontolerances, it may even be necessary to trim the thicknessof the nut, or the thickness of the belt clamp.

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130Z axis assembly

Next to be installed are the Z axis motor and Z cableplate (part #22). With two lock‐nuts and washers,install the stud into the cable plate as seen in the imageto the left.

Install the motor and cable plate to the Z motor mountswith 10‐32 x 1.75" socket head cap screws or machinescrews. The assembly should look like the imagesshown on this page.

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131Z axis assembly

Slide the Z rail assembly into the carriage bearings fromthe bottom. It may be easiest to work by laying thegantry assembly on its back.

Assemble the anti‐backlash nut to the bottom of the nutplate (part #27) with four #4 machine screws and nuts, asseen in the image to the right. Thread the leadscrewabout half way into the anti‐backlash nut.

Thread the motor coupler onto the top of the leadscrew.Thread it on so that the end of the leadscrew is alignedwith the slot that is cut through the coupler. Theassembly should look like the photo to the left.

If using a motor coupler made of Delrin plastic, an additionalset screw should be added, as shown in the image to the left.Drill and tap with #10‐32 threads for this set screw. This canthen be tightened against the flat on the motor shaft for amore secure connection.

NOTE:See the addendum on page 171 for an alternative lead‐screw assembly that includes the addition of thrustbearing. Following the procedure in the addendum isHIGHLY RECOMMENDED.

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132Z axis assembly

Position the leadscrew assembly as in the image to the right,so that the motor coupler is aligned with the motor shaft.Slide the coupler onto the shaft and tighten its screws tosecure it to the shaft.

Let the Z rail assembly slide down so that the studs on thebottom of the nut plate block go through the holes in thenut plate.

Install two lock‐nuts as seen in the image to the right.Thread the nuts on so that they are not quite touching thenut plate. Note that the studs are close together, whichmay prevent the use of washers.

NOTE:See the addendum on page 171 for an alternativelead‐screw assembly that includes the addition ofthrust bearing. Following the procedure in theaddendum is HIGHLY RECOMMENDED.

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133X axis rail installation

The next step will be to install the X rails to the machinebase. Begin with the four rail parts shown in the image tothe right:

part #28‐ X railspart #29‐ X rail angle leftpart #30‐ X rail angle right

Assemble the rails to the angles with hex head 1/4‐20 x1/2" bolts. Use a single lock washer beneath the head ofeach bolt. As seen in the lower left photo, the threads willprotrude too far beyond the face of the rails. Like the Y railthat is attached to the gantry, the threads must notprotrude beyond the rail face. Do not use additionalwashers beneath the heads of the bolts to correct this. Thethread length of the bolts must be shortened. This can bedone before inserting the bolts, or as was done here,carefully ground down after assembly with a disc grinder.

With the bolts appropriately shortened, adjust the rails so thattheir lower edge is flush with the bottom face of the angles.Tighten the bolts so they are snug tight. Do not fully tighten, asfurther adjustment of the rail positions will be done later.

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134X rails

Using four #10‐32 x 1" socket head cap screws, or machinescrews, install the X stepper motor (with pulley installed)and right plate (part #31) to the right angle and rail. At thispoint there will only be two screws sandwiching theassembly together, so use caution when handling.

Note that the top edge of the X rail angles have been grounddown in height. This will provide clearance for bearings thatcontact the edges of the X rails.

Place the assembly from the step above into position on themachine base. Place the left plate (part 32 X) and left rail/angleassembly into position on the other side. The correct positioningof these parts is with the rear faces flush with the rear face of thebase, as seen in the left image.

Secure the plates/angles to the base with the lag screws and a flatwasher beneath each head. Fully tighten the 7 lags on each sidethat only go through the plate. Adjust the angle/rail assembliesso that there is .1875" between the edge of the plate and the rearface of the X rail, as shown in the image to the right. Measure atfront and rear points along the rail to maintain a consistent.1875" overhang. This will provide an initial adjustment. Tightenthe front and rear lag screws that go through both plate and angleso they are snug, as seen in the image to the right.

Measure between the inside faces of the X rails at thefront and rear of the machine as shown to the right. Ifeverything has been constructed accurately, thisdimension should be 24.125". The rails need to be asparallel as possible, so if the measurements do notmatch, loosen the lag bolts slightly and carefully adjustthe positioning. There should be less than 1/32"discrepancy between the front and rear measurements.Aim to achieve rails that are as parallel as yourmeasuring method will allow. With the rails positionedparallel, install the remaining lag screws and fullytighten all of them.

.1875"

24.125"

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135gantry and preliminary adjustment

Once the X rails are parallel, attempt sliding the gantryassembly onto the rails, as seen in the photo to the left.Go slowly and carefully with this. There is little clearancebetween the lower bearing bolts and the machine base,and the bolt heads can gouge the surface of the base if thegantry is not slid exactly straight onto the rails. The tightclearance can be seen in the image to the right.

To keep the bolt heads from rubbing, a preliminary adjustmentshould be made to the bearings. This will keep the gantrycentered within the rails and allow it to travel smoothly alongthe length of the rails. A complete alignment to the rest of thebearings will be performed later. Begin by adjusting the twobearings circled in the right image. Hold sideways pressureagainst the gantry, pushing these two bearings against theface of the X rail. Use the set screws to adjust the bearings sothe the two lower bearing bolt heads clear the base by about1/16". Place a square between the X and Y rails to check thatthey are perpendicular to each other. Tighten the nuts tosecure the bearings that have just been adjusted.

As seen in the middle left image, adjust the two bearingsthat ride against the rear face of the right X rail. Tightenthem so that the gantry feels rigidly attached to the rail,with no perceptible play. Readjust as necessary to get thegantry at exactly 90 degrees to the X rails, as seen to theleft. Consult the adjustment techniques on page 161 tohelp make this alignment.

Adjust the two bearings circled in the image to the right.They should be set so that the gantry is raised high enoughthat there is no interference between any parts as it ispushed forward and back along the rail.

This series of adjustments should allow the gantry tosmoothly roll.

90

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136X belt assembly

When the gantry is rolling smoothly, with no interferenceat any point along its travel, install the X belt components.Begin with the X belt pulley adjuster (part #33). Install thehex head bolt into the threaded hole. This is anuncommon size of hex head bolt and may be difficult tosource locally. If one cannot be easily located, a 5mm x .8pitch metric bolt may be substituted. The thread pitch isnearly identical to the #10‐32 size, but the outsidediameter is a few thousandths of an inch larger. The 5mmbolt threaded into the #10‐32 hole will be serviceable inthis situation. If the metric bolt will not thread in easily,run the #10‐32 tap through the hole again.

First, hook the 200 tooth belt around the pulley on the Xstepper motor. Assemble the bearings to the pulleyblock with 5/16‐18 x 2" socket head cap screw or hexhead bolt. As on the gantry pulley, use two fenderwashers as flanges. Use a single flat washer betweeneach fender washer and the bearings. Hook the otherend of the belt around the pulley assembly and drop itdown into position, as seen in the left image.

As seen to the right, insert a 5/16‐18 x 2.5" socket headcap screw through the hole that is adjacent to the pulleyblock. Install a washer and nut on the other end of thescrew and tighten. This cap screw serves as a solid stud,against which the pulley adjuster will push.

Install a washer and nut on the bottom of the idler pulleycenter bolt and tighten so that the block is just free to slidesideways. With a small wrench, back the small hex bolt out,to put tension on the belt. When proper tension has beenachieved, tighten the nut.

Install the belt plate (part #09) and the belt clamp (part #10)as seen in the image to the right. As on the Y belt clamp,install a small shim behind the top edge, as circled in red.

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137cable arm assembly

Using the exploded‐view drawing on page 35, assemble thecable arms, as seen to the left. Make careful note of where thelarge diameter washers with enlarged holes are placed.

The bearings in this assembly are being used as thrust bearings,which is not the direction in which they are intended to beloaded. To avoid premature wear of the bearings, the nuts onthe studs must be adjusted so that they are tight enough to holdthe assembly rigid, but not so tight as to introduce excessive sideloads. The bearings are being used in this manner because theyare the same type that are used throughout the machine, andare inexpensive when sourced in bulk. They could easily bereplaced with proper thrust bearings if desired.

Install the assembly to the gantry, as seen in the upperright image. The cable arm assembly should cantileverfrom the gantry without sagging.

Push the gantry all the way to the rear of its travel.Working from beneath the gantry, hold the cable arms sothat they are as horizontal as possible, and mark thelocations of the holes in the cable arm mounting blockwhere it contacts the rear plate.

Pull the cable arm assembly away from the machine base anddrill a 1/8" pilot hole in the center of the hole marks. Installthe mounting block to the base with two 1/4" x 1.25" lagscrews, as seen to the right.

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138epoxy bed

To facilitate alignment of the machine to a high level of accuracy,a perfectly flat surface should be used as a reference plane, fromwhich all measurements can then be based. There are severalpossible methods of doing this. The simplest is to use the woodenbed of the machine as a reference surface. If it can be determinedthat it is adequately flat, it can be used in this capacity. Mostlikely, it will have enough deviation from true flat to require usinga flatter surface. This can be done in several ways. One is totemporarily place an object known to be very flat, such as asurface plate or lapped glass plate, securely on the bed so that itcannot move during the alignment process. A second method,used here, is to pour a thin layer of epoxy resin on the bed to levelit. An epoxy with a very low viscosity will self‐level and result in asurface that is very flat, creating a relatively low cost surfaceplate that is integrated into the machine.

Prior to pouring the epoxy, the bed area must be as levelas possible so that the epoxy will be a consistentthickness. If there is a large difference in thickness of theliquid epoxy, surface tension can result in an imperfectfinished surface. A larger volume of epoxy would berequired to overcome this tendency. To level themachine, place it on a solid surface that cannot moveduring the duration of the time the epoxy requires to cure(at least 24 hours). The machine can be placed on fourbolts with nuts threaded onto them, to serve asadjustable feet. The bolts used here were 3/8” diameter.

With the machine on a solid and stable surface, use ahigh quality level to set the bed of the machine as level aspossible. Check for level in multiple directions, as seen inthe images on this page. Use the bolts to adjust thecorner heights of the machine as necessary to achieve alevel machine bed area. Note that if the bed area is notperfectly flat, which is to be expected due to typical woodconstruction tolerances, achieving a “level” bed may be acompromise between errors in several directions. Findthe best average of the errors that is possible.

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139epoxy bed

To pour the epoxy, it is necessary to establish a watertight damto contain it to the bed area. This was done here with strips ofpainter's tape applied to the front and rear edges of the bed.The poured epoxy will only be approximately 1/8” thick, butmake sure the dam is significantly higher than this. What ismost important is that the area will have no leaks. The epoxy isvery thin and will run out of the smallest crack or area ofporosity. Make sure the joint between the bed of the machineand the vertical skin panels is watertight. If in doubt,additional paint may be applied to seal very fine openings, or acaulk may be used for larger gaps.

Use an epoxy with as low a viscosity as possible. The brand usedhere has a viscosity of about 550 cps, which is quite thin. Note thatthe warmer the liquid epoxy resin, the thinner it will be. However,if it is warmed too much, it will cause it to harden too fast. An idealcompromise is to get the epoxy to about 85‐90 degrees Fahrenheit.The temperature of the room should also be high. If it is not, thewarmed resin will cool very rapidly when spread thin. The resin canbe warmed by placing the closed containers in a bucket of hotwater for 15‐20 minutes. Warm the resin before mixing the twocomponents together to activate. Use a slow hardener to allowmaximum time for the resin to flow out to a flat surface.

Mixing a total of 24 fluid ounces of epoxy resin will result in anaverage thickness of just under 1/8”. This is about the minimumamount to coat a base that is already reasonably flat. 32 fluidounces is suggested, as it will flow out across the surface moreeasily. The more inaccurately the wood base was constructed, themore epoxy it will take to arrive at a perfectly level coating ofepoxy. Although a high quality epoxy will have few solvents andwill produce very little odor, make sure there is adequateventilation in the work area. Set up an exhaust fan if possible.Double check that the machine bed is as level as possible and mixthe epoxy. Use a graduated cup for accuracy and follow themanufacturers mixing directions.

Pour the mixed epoxy into the bed area, and use a spreader to tryand achieve a consistent thickness across the surface. The resinwill self‐level, so it need not be perfect, but the entire surfaceshould be coated, including into the corners and edges. Be carefulboth when mixing the epoxy as well as spreading it that excessiveair bubbles are not introduced. Trapped air bubbles will standproud of the flat plane of epoxy when dried. After spreading, allowthe resin to harden for at least 24 hours. Do not disturb the themachine during this time.

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140cover assembly

The cover assembly is attached to the base along its lowerrear flange by four screws. Other than these screws tosecure it, the cover primarily rests on the machine baseunder its own self‐weight.

Prior to attaching the cover, thin foam strips were applied to theedges that will contact the machine base. These were alsoapplied to the surfaces where the two halves of the cover cometogether. The foam will cushion the cover to prevent vibrations,as well as seal any gaps to prevent sound transmission. Thefoam used here was cut from sheets of a medium density foamrubber that was purchased at a craft store. It was applied witha high temperature hot‐melt glue gun.

Two fluorescent strip lights were installed in the top inside ofthe cover. Slots were routed in the bottom of the flange toallow their power cords to exit the cover. The foam strips wereinstalled in a manner to allow placement of the cords beneaththem.

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141cover and rear door

Strips of foam were also placed around the perimeter ofthe rear door face, where it will contact the machinebase. A hole was cut in the door with the hole saw forpassage of the router power cord. The door was fastenedwith six wood‐screws.

A rear door is fitted, to cover the hole at the rear of themachine. The intent of providing the door is that it can allowstock that is longer than the machine bed to pass through,giving a larger effective work area. Depending on anticipatedfrequency of use of this feature, the rear door can either bescrewed in place, as seen here, or can be installed with hingesfor easier operation.

A latch was not installed on the front door, as it is held in placeduring machine operation by its self‐weight. However, a latchmay be installed if desired. Lifting the front door, it can simplybe rested on the rear cover half.

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142installation of electronics

INSTALLATION OF ELECTRONICS:

A complete guide to installation of the electronic drivecomponents is beyond the scope of this manual. This islargely due to the vast number of different drivemanufacturers and models, each with their own wiringrequirements.

A brief installation overview of two popular drive boards willbe covered here. However, this should be used asREFERENCE ONLY, and the manufacturer's installationinstructions should be considered the definitivedocumentation for wiring. The two drives covered here willbe the Xylotex and the Gecko G540. Wiring diagrams aregiven for each, including emergency stop switches and limitswitches. There are often multiple methods of configuringthese switches, so again these diagrams should be used asreference, and considered supplemental to thedocumentation provided by the manufacturer.

While the installations shown here are for specific modelsof drive boards, the general procedure may be similar formodels of boards from other manufacturers.

Machine operation is possible with a minimum ofcomponents: a power supply, drive board, and steppermotors. However, the system should not be consideredcomplete without the addition of an emergency stop switchand limit switches. These provide protection to both themachine and operator.

General ElectronicsInstallation Sequence:

1. Install wiring to motors

2. Determine locations ofcomponents in electronics bay.

3. Connect power supply tomotor drive.

4. Connect motor cables tomotor drive.

5. Connect emergency stopswitch.

6. Connect limit/homeswitches.

7. Firmly fasten all componentsin place.

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143wiring the machine

It can be helpful to install the electronics on the machine beforemaking its final mechanical adjustments. This will allow easilyjogging the machine into multiple positions with the computer,which will especially be helpful on the Z axis. The exact wiringprocedure will depend on the particular motor drive(s) andother components being used. Also, if electronics componentsare purchased as a kit, much of the wiring may already be done,using pre‐installed connectors, resulting in a nearly “plug andplay” system. This section will illustrate the general routing ofcables on the machine.

The cable arms provide a means of organizing the cables thatrun to the gantry, and control how they are flexed as themachine travels. Route the wiring for the Y and Z steppermotors as shown in the photos. Simple cable ties are used tosecure them to the cable arms. Be sure that there is no waythat the cables can hook anything or bind as the gantry andcarriage move through their full range of motions. Be sure toprovide enough cable length on all 3 stepper motors toadequately reach the location of the drive board, without beingpulled taut. The power cable for the router, and limit switchwiring can also be run along the cable arms. Try to maintain asmuch distance between each of these parallel cables aspossible to prevent transference of electrical signal noise.

The vertical threaded rods on the cable plate and the center ofthe gantry may be used for cable attachment. It may be foundthat the cabling flexes more smoothly without fastening it tothe rod on the gantry. If this rod is not used, cut it down shorter,so that cables can not get caught on it.

In the image to the left, the location where the drive boardwill be mounted has been marked. It will be mounted onthe four nylon stand‐offs that are next to the screws. Anawl was used to create a pilot hole, and the mountingscrews were fully threaded into position without the boardpresent. This will form threads into the wood, which willallow a more careful feel for how tight they are wheninstalling the board. This can help avoid over‐tightening,putting too much pressure against the board. This alsoprevents having to put a lot of pressure on the screwdriver,which could cause it to slip off and damage the board.

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144cables

There are multiple types of cable which are advertised for useon CNC machines, and not all are equal in performance. Threetypes are shown in the image to the right. There are severalattributes that are important to consider for machine wiring.The first is the flexibility of the cable. As the machine movesthrough a range of motion, the cables must flex toaccommodate that movement. There are different flexibilityratings available. All three cables to the left are advertised as“flexible,” however, only the one on the far right is classified as“continuously flexible” and is rated for millions of movementcycles. Its large diameter is due to a thick silicone rubber casing.It can also be seen that this cable has a high number of very finewire strands, rather than a few thick, stiff strands which willfatigue quickly. The other two cables are only “flexible” in thatthey can be flexed into position during a wiring installation.They are not intended to be subjected to flexing during service.If continuously flexed they may break. This is crucial, as manytypes of drives will be destroyed if a wire breaks while it is underpower.

The other cable feature seen here is shielding. Shieldingprovides a way to neutralize electrical noise, which may causeproblems with motor operation, or false limit switch signalsbeing sent to the control software. Wires may be twisted inpairs, which also helps to neutralize noise signals. The cable onthe far left is unshielded. The middle one uses a thin metalizedmylar strip. The right one uses a heavy stainless steel braiding.When installed on a machine, this shielding “tap” that runsthrough the cable will be connected to ground.

Some method should be used to provide a seal where thecables enter the machine housing. Without this, dust will beable to enter the electronics bay. The cables should also besecured in some manner, so that they cannot accidentally bepulled through the hole. The plugs shown here, in theimages to the right, were milled from 3/4” MDF, and were thefirst parts to be cut on the finished machine. The cutting ofthese parts can be seen on page 168. They fit by a lightpress fit, and were tapped into place with a mallet. Theygrip the cables tightly, preventing any movement.

XB# XB XA# XA YB# YB YA# YA ZB# ZB ZA# ZA

P10P12P13P11P14P1P15P16P17GND

VCCGND

VBB

GND

MS1MS2ENA#

X AXIS

MS1MS2ENA#

X AXIS

MS1MS2ENA#

X AXIS

GND

ENAZ

ENAY

ENAX

GNDVBB

TPX

TPZ

TPY

GND

DIR_

ASTEP_A VCC

GNDVCC

24 volt p

ower su

pply

24v cooling fan

to electricaloutlet

to X motor to Y motor to Z motor

10K

10K

10K

X lim

itX lim

it

Z lim

it

Y lim

itY lim

it

10K

emergencystop switch

NOTE:All limit switches and emergencystop switch to be wired NC(normally closed.)

NOTE:Color of motor wiring may vary,depending on manufacturer.

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145electronics‐ Xylotex wiring diagram

wiring diagram forXYLOTEX 3 axis board

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146electronics installation‐ Xylotex

INSTALLATION OF XYLOTEX DRIVE

Wire the power supply to the drive board. This is best done offthe machine at first, as the board requires adjustments to bemade to it. The Xylotex requires setting the individual outputvoltage for each motor axis. This can allow use of motors withdifferent power requirements on each axis. This adjustment isdone with only the power supply hooked up, NOT THE MOTORS,and using a digital multimeter (left photo). A smallpotentiometer is turned to achieve the desired output voltage.Consult the Xylotex documentation for your board to determinethe voltage value that is required. Be sure to not exceed themaximum voltage specified, as damage to the board can occur.With this "Vref" voltage set for each axis, the board can bewired to the motors (right image).

In the image to the right, the drive board is mounted andwired to the power supply and motors. The power cordfor the power supply enters from the right, and is routedup over the board and into to the left side of the space.Notice it is knotted to prevent it from being pulled throughthe hole.

When using this board at its higher range of possiblevoltage outputs, a cooling fan is required. Here a smallfan is mounted to a small piece of paper mat‐board,which is held in position with small wood screws. Thefan is powered by the drive board itself, and is positionedwhere it will blow air over the heat sinks on the board.

A couple of small pieces of wood blocking were attachedto the top surface of the electronics bay. The powersupply was attached to this, essentially "hanging" fromthe top. This put it in a convenient orientation to run allof the wiring.

Plan your layout carefully so that wiring is neat and iseasily traceable. More wiring will be added later for anemergency stop button and axis limit switches, so plan forthis wiring as well.

Y AXISX AXIS Z AXIS A AXISTRIM

PARALLEL PORT

A9

87

6B

12345

R

STP = DB25 P4STP = DB25 P5

TRIM

A9

87

6B

12345

R


TRIM

A9

87

6B

12345

R


TRIM

A9

87

6B

12345

R


POWER

FAULT

ON

OFF

CHARGEPUMP

1 2 3 4 5 6 7 8 9 10 11 12

emergencystop switch

24 volt p

ower su

pply

to electricaloutlet

+VDC

‐VDC

X limit X limit

Y limit Y limit

Z limit

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147electronics‐ Gecko G540 diagram

wiring diagram forGecko G540 drive board

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148electronics‐ Gecko G540 installation

INSTALLATION OF THE GECKO G‐540 DRIVE

If operating the Gecko G540 drive with supply voltage and outputcurrents that are near the high end of its capacity, heatsinksshould be installed to reduce operating temperatures. Theheatsinks being installed here were purchased as a kit fromSoigeneris, and are intended specifically for use on this drive. Itsupplies three individual heat sinks, which are attached withincluded double sided tape.

The mating surfaces of the heatsinks and the bottom of thedrive should be cleaned with rubbing alcohol beforeinstallation. Carefully apply the tape to the bottom of thedrive. As seen in the image to the right, holes were cut in thetape at locations of subtly protruding screws, to allow theheatsinks to sit as flush to the surface as possible.

Carefully position and adhere the heatsinks into position onthe bottom of the drive. In addition to the heatsinks, a fancan also be used to further reduce drive temperatures.

to X m

otor

XB#

XB

XA#

XA

resistor value =motor currentrating x 1000

Typical Gecko G540bipolar motor wiring.

NOTE:Color of motor wiring may vary,depending on manufacturer.

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149electronics‐ Gecko G540 motor wiring

The Gecko G‐540 drive requires installation of a 1/4 watt,5% resistor in the wiring to each motor, to properly controlthe amount of current that is supplied to that axis. As perthe Gecko documentation, this resistor is installed at thedrive end of the motor wiring, within the DB‐9 connectorbackshell. The value of this resistor can be found bymultiplying the motor current (up to 3.5 amps) x 1000.Thus, for a 2.5 amp motor, the proper resistor would be2.5K ohm, 5%, 1/4 watt.

There are a couple of alternatives to installing this resistor. Oneis to purchase a G‐540 kit from a supplier who incorporates theproper resistor directly into molded wiring for their motors.This avoids hand soldering motor supply wiring and sourcingthe proper resistor. It results in a system that is veryconvenient to assemble, being nearly “plug‐and‐play”.

Another alternative, if soldering your own motor cables, is touse a Soigeneris EZ‐G540. This component, which is shown inthe three images to the right, incorporates an adjustablepotentiometer into a DB‐9 backshell. By using this device, iteliminates soldering a separate resistor. It also provides largesolder pads for the motor wiring, making soldering easier thanwithin a standard DB‐9 connector. Once installed, thepotentiometer is adjusted to set the proper resistance value.A digital multi‐meter must be used to measure this setting.

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150electronics‐ Gecko G540 installation

With the proper resistor installed in the motor cables, they canbe installed on the machine, as per page 143. In the image tothe right they are seen extending into the electronics bay.

Also seen in this image is that the location of the drive boardhas been determined, and mounting screws with nylonstandoffs have been installed.

In the image to the right, the power supply has been placed inthe electronics bay. It is not yet fastened in place, allowingmovement for ease of making wiring connections. Its leads arerouted to the position of the drive board.

One end of the wiring from an emergency stop switch has alsobeen connected to the power supply ground, and is placed inposition to be connected to the drive.

The first connection to the drive that should be made is toconnect only the power supply. Connect the positive lead toterminal 11 and the negative lead to terminal 12. With thepower supply connected, turn it on, and the red LED on theboard should illuminate, as seen in the image to the lower left.

After verifying that the red LED illuminates, turn off the powersupply. Connect the lead from the emergency stop switch toterminal 10. This switch should be wired normally closed. Asper the Gecko instructions, disable the charge pump switch.Turn on the power supply, and the green LED on the driveshould illuminate.

Turn off the power again and attach the motor cable DB‐9connectors to the drive. The system should now beoperational. Connect a DB‐25 cable to the PC parallel port, andcheck that the machine can be jogged through each axis byusing the machine control software.

The final installation step is to adjust the trimpot of each axison the drive. Consult the Gecko documentation for thisprocedure. It is most easily accomplished with the motorsdisconnected from the belts/leadscrew. To keep the motorsturning at the desired rpm for tuning, a short G‐code programcan be written, or the jogging speed adjusted.

X limit Y limit Z limit

X home

Y home

Z home

P10P11P12P13

GND

MOTO

R DR

IVE

X home X limitP10P11P12

GND

MOTO

R DR

IVE

Y home Y limit

Z home Z limit

X home Y home Z homeP10

GND

MOTO

R DR

IVE

X limit Y limit Z limit

X home X limitP10P11P12

GND

MOTO

R DR

IVE

Y home Y limit

Z home

X limit

Y limit

Z limit

P10P11P12P13P14P15

GND

MOTO

R DR

IVE

Z home

Y home

X home

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151electronics‐ limit switches

Regardless of type of motor drive used, the system should be installed with limitswitches. These are small microswitches installed just before the end of travel oneach axis. When the machine reaches this point in travel, the switch istriggered, sending a signal to the machine control software, which stops motion.This prevents the machine from accidentally slamming into the end of its travel,potentially causing damage or operator injury.

In addition to adding a level of safety, they can also be used to “home” themachine. Each time the machine is turned on, the machine control softwarecan be instructed to “home all axes.” The software will sequentially move eachaxis of the machine in a desired homing direction, until it triggers a switch. It willthen back off the switch a small amount so that it is no longer triggered. Thesoftware will consider this the zero coordinate “home” position for the axis. Thiswill provide a consistent 0,0,0 starting position each time the machine is used.The software will now know where the tool is positioned in space.

Note that this 0,0,0 machine coordinate does not have to be considered as the0,0,0 position on a part when running a job. A separate 0,0,0 work origin pointcan be set for each job. This exists independently of the machine coordinates,which will always have 0,0,0 in the same position.

Having consistent 0,0,0 machine coordinates that are found through homingallows use of “soft limits.” These are travel limits that are set through thesoftware, that prevent the machine from traveling as far as a limit switch duringoperation. This will be discussed more fully in the section on Mach3 setup.

Limit switches can be installed in many wiring configurations. Generallyspeaking, a compromise must be found between giving the software as muchknowledge of machine position as possible, while not using an excessive numberof parallel port input pins. The diagrams on this page illustrate some of thepotential configurations for wiring the same number of switches.

At one extreme, all switches can be wired through a single pin. No matter whichswitch is activated, motion will be stopped. However, the software will have noway of determining which switch was triggered. Correct machine homing canstill be done, as the software knows which axis it is putting into motion.

At the other extreme, each switch is wired to a separate pin. This gives thesoftware the maximum knowledge of which switch is triggered. However, itrequires more input pins than are typically available, in addition to a largeamount of wiring.

The diagram in the lower right was used on this machine. It is considered a goodcompromise between maximizing software knowledge while minimizing inputpins. Note that limit switches are always installed normally closed, so that anybreakage of wiring will stop the machine. Also note that a switch in the Z‐direction is not used. Due to the variability of tool lengths, it is more practical tocontrol motion in this direction through soft limits.

NOTE:Diagrams represent input logic only,they are not wiring diagrams for anyspecific drive. Particular drives mayrequire resistors at each switch input.Consult documentation from drivemanufacturer for requirements.

pin 11pin 12

GND

MOTO

R DR

IVE

pin 10

Y homeY limit

Z ho

me

X ho

me

X lim

it4 conductorcable

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A single, 4 conductor cable can be used to wire the limitswitches for the Z and Y axes. A general diagram of thisconfiguration is shown to the left. Note that some drives,such as the Xylotex, may require resistors at each switchinput pin.

The image to the right shows this wiring as it was applied toa Gecko G540 drive. Note that this cable is shielded, and thetap is also connected to the ground point. The coil of singlewire in the center will be used for the X axis limit switches.

In the image to the right, all of the limit switch wiring isconnected to the Gecko drive, as well as grounded to thepower supply. With all of the connections made, the drive issecured in position on the nylon standoffs.

Wiring was soldered to the microswitch connectors beforeattaching them to their mounting brackets, as seen to the left. Besure to connect the wiring to the correct lugs, so that the switchwill be operating in the normally closed configuration.

The switches are next installed on the machine. The image to theright shows the front X axis switch, which is triggered by theextended length of threaded rod. A small hole is drilled to routethe wiring directly into the electronics bay.

to ground

to pin 11to pin 12

to Y and Z axislimit switches

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The X axis limit switches are mounted as seen in the images to theleft and right. The brackets were attached to the base with screws.A stack of washers is used as a spacer between the bracket andbase, with the switch sitting tightly to the surface of the base skin.

Install the switches in a position where they are triggered by theextended length of threaded rod. Install the mounting screws sothat there is some amount of adjustability to the brackets. Theswitches should be able to be adjusted so that they trigger about1/4” away from any hard collision at the end of the axis travel.

The single Z axis switch is mounted as in the image to theright. It is also triggered by an extended length of threadedrod. Washers were used behind the bracket, to provideclearance for the heads of the screws that attach the switch tothe bracket.

Mounting the Y switches on the gantry requires drilling andtapping #10‐32 holes in the gantry tube, as seen in the imageto the left. Carefully determine the placement of the switchesbefore drilling. Note that the Y switches are triggered by theoutermost carriage bearings.

The images to the left and right illustrate the installed Y axisswitches. Washers were again used between bracket andgantry to provide clearance for screw heads. Wiring wasfastened to the gantry with strips of electrical tape.

With all switches, make sure that the connectors cannotpossibly ground to any part of the machine, as this willinterfere with their proper operation.

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154side door

A side door may be provided to cover the electronics bay. Thisis also a convenient surface for mounting an emergency stopswitch. A door can be fabricated from any flat material. Due tothis, the material for the door has not been included in the Billof Materials. The door shown here was cut from a piece ofpolycarbonate sheet, which was sanded on both sides with finesandpaper to give it a frosted appearance.

The only limitation on door material is that it should be able towithstand the force of hitting the emergency‐stop switch if it ismounted here.

The hole for the emergency stop switch was cut by stitch drillingand filing. The same technique was used to cut a hole formounting the input cable for the electronics. A series of holeswere also drilled to provide airflow for the power supply fan, and acooling fan that will blow air across the drive board.

The door was mounted with two 1 1/2” utility hinges and twomagnetic latches. A length of wood was screwed to the door toprovide a handle, and to stiffen the edge of the thin material.

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155Mach3 setup

Basic software configuration will allow use of the computer tojog the machine during alignment, and provide preparation forthe first use of the machine. Setup of Mach3 software is shownhere, although many basic concepts will apply to otherapplications, such as EMC2. Extensive documentation isprovided by the software developers, and it should be followedclosely. The setup shown here should be considered assupplemental reference, and is no way intended to provide thefull knowledge necessary to use the software.

If you haven't already, install the software per the developer'sdirections. This may involve rebooting the computer andrunning a program to test the operation of the parallel port.Some manufacturers of motor drives will also provide a Mach3.xml file, which creates a “profile” that has numerous settingspreconfigured for the particular drive. Gecko is one suchmanufacturer, which provides a .xml file for its G540 drive. If an.xml file is available for your drive, install it in the Mach3 installfolder.

Parallel Port settings:Config>Ports and Pins>Port Setup and Axis Selection (upperright image)This screen is used to activate the correct port. Consulting theWindows Device Manager may be necessary to determine theport address. The other setting on this screen is for KernelSpeed. This setting determines the frequency of the outputpulse rate. A higher pulse rate translates to higher motor rpm.For typical stepper motor systems, 25,000Hz is adequate.

Config>Ports and Pins>Motor Outputs (middle right image)The motor wiring must be configured to correspond to specificparallel port pins to receive proper output signals. Consultmotor drive documentation for this information. If using a drive‐specific .xml file this should already be set.

Jogging:On most screens within Mach3, the arrow keys and PgUp/PgDncan be used to jog the 3 axes. This function may need to beconfigured by going to Config>System Hotkeys. In addition tousing keyboard input, the Manual Pulse Generator fly‐out maybe used. Pressing the tab key makes this screen appear, andgives increased functionality for jogging. This can be used forcontinuous jogging, or by discrete steps. Do not use the joggingfunction until the correct motor settings have been entered(following page.)

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156Mach3 setup

Motor Tuning:Config>Motor Tuning> desired axisThe software must know how many step pulses must be sent tothe motors to result in machine movement of one unit (inch ormm.)

For the X and Y axis belt drives:Motor steps per revolution =200Timing belt pitch (.200”) x teeth on pulley (10) = 2.00” per rev.Microstepping value (Gecko G540 = 10x)

One motor revolution (200 steps) = 2.00” of movement. Thus100 motor steps = 1 inch of travel. However, since the motordrive has a microstepping feature, this results in a higher numberof steps per revolution. Thus, for a 10x microstepping drive, 10xmicrostepping X 100 steps/inch = 1000 steps/inch. For thisdrive, 1000 steps/inch will be the value entered in the X and Yaxis fields titled “Steps per.”

For the Z motor axis, the factors are:Motor steps per revolution =200Leadscrew pitch (1/8” x 4 start acme) = .50”” per revolution.Microstepping value (Gecko G540 = 10x)

One motor revolution (200 steps) = .50” of movement. Thus itrequires 2 revolutions of the motor shaft to cause one inch ofmovement, or 200 steps X 4 revolutions = 400 steps/inch.Factoring the microstepping feature, this again results in a highernumber of steps per revolution. Thus, for a 10x microsteppingdrive, 10x microstepping X 400 steps/inch = 4000 steps/inch.For this drive and particular leadscrew pitch, 4000 steps/inch willbe the value entered in the Z axis field titled “Steps per.”

Velocity:This sets the maximum speed, which is used during jogging orrapid moves. This may be limited by the particular electronicsbeing used, but in general the machine is capable of very highspeeds. This should be kept to a reasonable speed to avoid themachine moving faster than the operator's response time to hitthe emergency stop switch.

Acceleration:This sets the acceleration and deceleration of the motors. Thisshould also be kept to a reasonable value, as stepper motors canbecome generators under deceleration. This can feed excessivevoltage back to the drive, potentially causing damage.

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157Mach3 setup

Limit Switch Inputs:Config>Ports and Pins>Input Signals

The software must be configured to know when a limit switch isbeing activated, as well as knowing on which axis the event isoccurring. The image to the right shows typical settings thatcorrespond to the wiring diagram used on pages 151/152. Theport# must correspond to which parallel port is being used tocontrol the drive. The pin number corresponds to how the limitswitches are wired through the drive (or breakout board.) On theGecko G540 and Xylotex drives, certain terminal connectionscorrespond to certain parallel port pin numbers.

Home Referencing:Config>Homing/Limits

The machine can be instructed to sequentially move eachaxis in a determined direction, until it hits a “home”switch. The limit switches, configured above, can also beused for this homing operation. No separate switches arerequired. By checking “auto zero”, as seen in the image tothe right, an axis will be included in the homing operation.The X and Y axes are typically homed in the negativedirection, while the Z is homed positive. Due to theparticular motor wiring, here it can be seen that thedirection of two motors required reversing, in order toorient the correct positive/negative movement directions.

Activating the REF ALL HOME command (circled in red inthe lower right illustration), each axis will move at areduced speed until it contacts a home switch. It willthen back away from the home switch slightly. Thisposition will be the zero coordinate for the axis. Thesethree 0,0,0 locations set the “machine coordinates.”

Soft limits:Config>Homing/LimitsRather than depend on limit switches for end of axisprotection, travel limits can be set through the software.These are distances from the 0,0,0 machine coordinates.The advantage of using soft limits is that the machine willgently decelerate as it approaches this travel limit, unlikethe abrupt stop caused by hitting a limit switch.

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158alignment

At this point the machine is basically finished and primarilyneeds alignment before use. The first alignment step will be toget the two X rails exactly parallel to the surface of the machinebed. This is done by measuring up from the bed at the frontand rear of each rail, and adjusting them so that themeasurements are equal. This can be accomplished to a highlevel of accuracy with some relatively simple tools.

The image to the left illustrates an adjustable height gauge thatwas constructed from some scrap rectangular tubing and alength of threaded rod. The tubing size was 1 1/2" x 2". Thesurfaces of the tubing are very flat and allow the gauge to sitflush against the bed without rocking. The top of the threadedrod was filed to a shallow point. Note in the images to theright that the threaded rod was bent very slightly to the side sothat it would reach exactly under the rails.

The height gauge is used in conjunction with a set of feelergauges (middle left image.) These are simply thin flexible metalstrips that are inserted into a gap to "feel" how wide it is. Theycan be purchased at any auto parts store for a few dollars.Adjust the threaded rod up under the front of the right X railuntil it is almost touching. Ideally, leave about .010" ofclearance. Use the feeler gauges to measure this gap. With trialand error, find the feeler gauge strip, or combination of stripstogether, that slides into the gap with just a faint amount ofdrag along its surface. Without changing its adjustment,reposition the height gauge under the rear of the right rail.Measure the gap between it and the rail with the feeler gauges.Loosen the bolts holding the rail to the rail angle andreposition it so that the gap is the same at the front and rear.This may take moving the height gauge from front to backseveral times and taking repeated measurements. With somepatience, the rails can be very accurately positioned this way.Do the same for the left rail. The right and left rail should eachbe the same exact same height above the bed.

equal equal

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159alignment

The two X rails should now both be parallel to the machine bed.The next adjustment is to set the Y rail parallel to the bed. Thisis done in a similar fashion, but we will now be adjustingbearings to effect its height.

We will again be using the height gauge and feeler gauges, thistime to measure the left and right sides of the Y rail (left andright images.)

The four bearings that ride along the tops of the X rails willneed to be adjusted (circled in the middle right image). All fourwill need to be exerting equal pressure downward on the railsso that the gantry will not rock. Again, this will require sometrial and error and multiple repositioning of the measuringgauge during the process. Tighten the nuts on the bearingbolts so that they are just slightly snug and then adjust the setscrew to reposition it before fully tightening the nut (lowerright image).

While adjusting these four bearings to get the Y rail parallel tothe bed, occasionally check that the front face of the Y rail is asclose to perpendicular to the bed as possible (left photo). Thecloser to perpendicular, the easier it will be to adjust the Zaxis later.

Take your time with these adjustments and be patient. It maytake multiple attempts to get the adjustment correct and maybe frustrating and time consuming at first. The process willproceed faster as you develop a feel for adjusting thebearings.

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160alignment

Once you are satisfied with the adjustment of the fourbearings that ride along the tops of the rails, next adjust thefour that ride along the lower edge. Move the gantry sothat the bearings line up with the four depressions in theinner skins, as shown in the lower right image. These areprovided to allow clearance to get a wrench onto the headsof the bolts. However, as the bolt heads are thinner thannormal, it will take a special wrench to fit onto them.

There are a couple of solutions to this. One is to simply grinddown the head of a standard wrench so that it fits. If you do this,grind the wrench slowly to avoid overheating the metal. Cool itoften by dipping it into water. Another solution is to use a readymade wrench. Many power tools have special wrenches to fittheir arbors that are thin. The lower left images shows a wrenchfor a router that was the required 1/2" size. Another option is tobuy a bicycle “cone wrench” that is made for working on bicyclehubs (wrench with blue handle in image.) Buy one in a 13mmsize. Note that this is a slightly loose fit on the 1/2" head (whichis 12.7mm) but should work fine. These do not need to beexcessively tightened, so no rounding should occur if the wrenchis squarely on the bolt head.

Adjust these four bearings until they lightly touch the bottomedge of the rails. This also requires acquiring a feel for how tightagainst the rail they need to be. They need to be tight enoughthat there is no free play, but not so tight that they increaserolling resistance. A good test is that with the gantry stationary,you should still be able to grasp the bearing and turn it againstthe rail. It should slip against the rail when turned with somepressure. It should not slip very easily, but should not turncompletely freely either. The tendency while adjusting may beto over‐tighten the bearings. It is easy to over‐tighten thebearings to the point where the stepper motors can not move themachine, or lose steps during movement. If in doubt, it is betterto go with an adjustment that seems slightly too loose ratherthan too tight.

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161alignment

Most of the bearings on the machine are adjusted insets, that simultaneously touch opposing sides of a rail.This may either be across the width (left illustration), oracross the thickness (right illustration). Keeping this inmind can help during adjustments, as there are a coupleof strategies that can be used to cause an adjustment tohave the needed effect.

Adjusting two bearings along one surface (the top twobearings in the upper left illustration) can cause eitherrotational shift or a parallel shift. Make theseadjustments with the opposing bearings loose.

Once bearings along one surface are satisfactory, adjustin the opposing set (middle left illustration.)

If all four bearings are making the desired amount ofcontact, a rotational shift can be accomplished byleaving two opposing ones alone, while adjusting theother two equal amounts in the same direction. (lowerleft illustration.)

The next bearings to adjust will be the carriage bearingsthat ride along the Y rail. First adjust the four that contactthe top and bottom edges (circled in the middle rightimage.)

While adjusting these four bearings, also try to get thecarriage itself perpendicular to the bed, as shown in thephoto to the right. The closer to perpendicular thecarriage can be set, the easier the alignment of the Z axisrail and Z screw will be later.

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162alignment

The Y axis bearings that ride along the front and rear faces ofthe rail are adjusted next. There are a total of eight bearings,that need to be adjusted as one group. Note that on the frontones, a single socket head cap screw secures two bearings at atime. Each bearing does have an individual set screw adjuster.

You may find it easiest to adjust these double sets of bearingsfirst (middle right image), and then adjust the rear ones in totouch the rail (upper right image.)

The rear bearings also use bolts with thinner heads forclearance, so the thin wrench will be needed here too.

Like with the previous adjustment, check often during thisadjustment to try and set the carriage perpendicular to the bed inthe front/rear direction. Again, this will make later Z axisadjustments much easier, and will result in smoother Z axisoperation.

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163alignment

The next adjustment will be to the Z axis rail. This needs to beadjusted so that it is perpendicular to the machine bed in bothside to side, and front/rear directions.

First adjust it side to side, using the four bearings circled to theright.

Jog the Z axis down so that it is at the lowest point of its travel.Be careful that the rail does not move low enough that it it nolonger captured between the top bearings. A small triangle orsquare can now be used as a gauge to set the railperpendicular.

When the Z rail is perpendicular to the bed, double check byflipping the triangle around and holding it up to the otherside. If your triangle is not exactly a 90 degree angle, or thebed surface is uneven, then flipping the triangle to the otherside will reveal the discrepancy, and that something isinaccurate.

Move the triangle or square to the front of the rail as shown inthe image to the right. Adjust the eight bearings that ride alongthe front/rear surfaces of the rail to get it perpendicular to thebed. These also have paired bearings on long socket head capscrews, so use the technique that was used on the Y rail.

All three of the machine axes should now be in properadjustment and alignment.

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164alignment‐ Z screw

The final adjustment is to the Z axis drive screw. There is nosimple place to directly measure to find its proper positioning, soit will take some trial and error. Begin by jogging the Z axis to itslowest position. Tighten the #4‐40 x 1" machine screws and nutsholding the anti‐backlash nut so that they are snug enough tohold it in position, but it can still be repositioned with some slightforce. Also snugly tighten the nuts securing the nut plate, and nutplate block. Each of these points can later provide adjustability.

Standing in front of the machine, visually align the drive screw sothat it is parallel to the Z axis rail.

Move to the side of the machine and do the same in thatdirection.

Jog the machine all the way to the top of its Z axis travel. Itshould not bind, and the sound from the stepper motorsshould stay consistent during the travel. Readjust asnecessary. It will probably require jogging the Z axis up anddown several times, readjusting each time, to finally get itcorrect.

Once it is in a satisfactory position, tighten all of the nutsfully. On the anti‐backlash nut, be sure to either usethread‐locking compound (the removable type), lock nuts,or lock washers. These are highly vulnerable to vibratingloose, and their small size does not allow excessivetightening without stripping threads.

If all is adjusted correctly, the Z leadscrew should be parallelto the Z rail when viewed both from the front and from theside. They should remain parallel in both directions as the Zaxis is jogged along its length. Binding may occur if the twoare not parallel during the entire length of travel.

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165router and mounts

Install the router mounts, as seen in the image to the left.Note that the mounts shown in this series of images arean older variation, and are not exactly the same shape asthe current design.

With the Z axis jogged to its lowest position, set atriangle or square against the faces that will contact therouter body. Note if the square touches both evenly. Ifthe mounts are not exactly perpendicular to the machinebed they can be shimmed into the correct position. Thinmetal foil or paper can be used as shim stock.

When satisfied that all of the clamping surfaces areperpendicular to the bed, install the router and front clamphalves. Tighten to secure the router.

Make sure that the router and cord clear all mechanicalcomponents as the Z axis moves through its full range ofmotion. The extended threaded rod that contacts the Z axis limitswitch can also be used to manage the router cord. Be sure thatit can not interfere with proper operation of the limit switch.Here a washer and nut were used to contain the cord.

5.500

0.50.5

1

1.5

2.75.25 .25

.50.75

2.750

1.00

0

1.50

0

0.500

1.375 .25

.50.75

1.500

1.00

0

.75

.50

Typical extrudedaluminum T‐slot track.(2) pieces, MDF.

(4) pieces, MDF.

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166spoilboard

Some method is required to secure workpieces to thebed area. The bed area should also be provided with asacrificial “spoilboard” wear surface that canaccommodate milling operations that cut through theentire thickness of the work. The spoilboard may be assimple as a piece of medium density fiberboard (MDF)that is fastened to the machine bed. Workpieces can inturn be screwed to this surface.

A more versatile system is shown here, which consistsof aluminum T‐track extrusions that are set within piecesof MDF. This provides a convenient and fast method ofclamping that does not require sinking screws into thespoilboard surface. Many types of clamping accessoriesare commercially available for T‐track systems.

The assembled pieces in the illustration to the left resultin a working surface that measures 15” x 15”. This sizewill allow the cutting tool to just extend beyond eachedge. This is necessary so that the router can be used tomill this surface flat after installation. The spoilboardcan also be resurfaced after it wears during use.

The assembly shown here used a piece of 3/4” plywoodas the center layer. This was used rather than MDF as itis easier to screw into. Any screw that penetrates intoMDF should be provided with a pilot hole to avoiddamage, as the MDF does not easily displace material.

The top MDF strips were fastened from the bottom,through countersunk clearance holes in the plywoodlayer.

Thickness of spoilboard:The Z axis of the machine has a substantial amount oftravel, and it should be kept in mind that the machinewill be most rigid with the Z axis at its highest. Thus, itis beneficial to mount the workpiece as high aspossible. If you anticipate cutting a consistent type ofparts, such as mostly parts cut from 3/4” thick wood,then the spoilboard can be constructed with this inmind. It can be built to a thickness that raises the workto a desired height. The spoilboard could also beconstructed in multiple layers, that could be removed tolower it when necessary.

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167spoilboard

The middle right image illustrates the finished spoilboardbefore mounting on the machine. Note that the top ofthe MDF surface is well above the top surface of thealuminum T‐track. This provides a safe thickness of wearsurface that would need to be penetrated before thecutter would contact the metal track.

The lower left image shows one type of clamp that isavailable for this T‐track system. Special T‐track bolts arealso available, allowing more custom clampingconfigurations. It is recommended to use clampcomponents that are made of plastic, brass, or other softmetals where possible. This will reduce the danger thatis possible if a clamp is accidentally hit by a cutting tool.

In the image to the right, the finished spoilboard ismounted on the machine bed. It was carefully located sothat the cutting tool can cut move just beyond itsperimeter for surfacing. It was also carefully positionedso that the T‐slots are as parallel to the X axis travel aspossible. This makes it easier to clamp material to thespoilboard in a position that is known to be parallel tothat axis.

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168first use

Congratulations, the machine is now complete and ready to beused. After familiarizing yourself with a CAM application, andgenerating G‐code to cut a part, here is a suggested procedure for thefirst use of the machine.

1. Home the machine by using the Mach3 REF ALL HOMEcommand. This will zero the Machine Coordinates.

2. Jog the machine so that the tip of the tool is in the location onthe workpiece that corresponds to 0,0,0 as it was defined in theCAM software. When in that position, use the buttons circled inthe image to the left to set the Work Coordinates. Note that thisdoes not alter the Machine Coordinates, which are still used tocontrol soft limit locations.

3. Jog the machine to make sure that soft limits are functioningcorrectly. The Soft Limits button (also circled in the left image) inMach3 needs to be activated, which will be indicated by a greenborder around the button.

4. Load a G‐code program. File>Load G‐code. The lines of codewill appear in the window that is circled in the right image.

5. Run the program. For the first time running a program it isadvisable to zero the Work Coordinate for the Z axis higher than theworkpiece. This way you will be “cutting air” and have anopportunity to observe if the program seems to be runningcorrectly. Keep a hand on the emergency‐stop button and click theCycle Start button in Mach3 (also circled in the right image.) Watchto see that the axes appear to be traveling the correct distance. Ifthere are any problems, the machine can be stopped by hitting theemergency‐stop button, or the red Stop button in Mach3 (circled atright.)

6. If all appears to be working correctly, set the correct Z axis WorkCoordinate, jog the tool a safe distance above the workpiece, turnon the router spindle, and run the program. Congratulations again,you've just cut your first part.

7. It is advisable to measure the finished part, to compare its cutdimensions to its design dimensions. If there is any variation, thesteps per inch values in the Mach3 motor tuning screens may needslight adjustment.

This concludes the building of the machine, and hopefully beginsmany enjoyable hours of machining parts. Be creative!

‐Bob [email protected]

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169parts suppliers

SUPPLIERSMetals

Online Metals1138 West EwingSeattle, WA 98119800_704_2157http://www.onlinemetals.com/[email protected]

Speedy Metalslocations in Wisconsin, Michigan, Texashttp://www.speedymetals.com/

Metals Depot4200 Revilo RoadWinchester, KY 40391http://www.metalsdepot.com/

Bearings

VXB Bearingshttp://www.vxb.com/Ebay vendoruser id: irvinemanstore name: VXB Bearings Skateboard and Slotcar

Stepper Motor Drives

Xylotex, Inc.2626 Lavery Court #307Newbury Park, CA 91320http://www.xylotex.com/[email protected]://groups.yahoo.com/group/Xylotex/

GeckoDrive Motor Controls14662 Franklin Ave.Suite ETustin, CA 92780http://www.geckodrive.com/http://groups.yahoo.com/

KelingCNC/Automation TechnologyAutomation Technology Inc2112 Stonington AveHoffman Estates, IL 60169http://www.kelinginc.com/‐vwide selection of motors and drives

CNCrouterpartshttp://www.cncrouterparts.com/‐GeckoG540/motor kit with molded cables

Longs MotorEbay vendoruser id: longsmotor99store name: Changzhou Longs Motor Co‐motors and drives. Ships from China.

Soigenerishttp://www.soigeneris.com/‐Gecko G540 drives‐G540 heatsink kit‐EZ‐G540 DB‐9 connectors with potentiometer

Power Transmission

Dumpster CNChttp://dumpstercnc.com/[email protected]‐anti‐backlash nuts‐motor couplings

McMaster‐Carrhttp://www.mcmaster.com/‐precision acme threaded rod‐many misc. components

Stock Drive Productshttp://www.sdp‐si.com/‐drive belt‐timing pulleys

Epoxy

Jamestown Distributors17 Peckham DriveBristol, RI 02809http://www.jamestowndistributors.com/‐MAS low viscosity epoxy

Ebay vendor:user id: polymerproductsstore name: Polymer Products‐low viscosity resin

Hardware

Bolt Depotwww.boltdepot.com‐hardware

BOLT IT UPEbay vendoruser id: 5137jonesstore name: BOLT IT UP‐hardware

Multiple Items

Hubbard CNCEbay vendoruser id: carolbrentstore name: HUBBARD CNC INC‐wide selection of CNC parts

NOTE:Momus Design has no affiliation withany of the vendors on this or thefollowing page. Inclusion here doesnot necessarily imply an endorsement.

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170software suppliers

SOFTWAREMachine Control Software

‐Mach3 CNC controllerArtSoftNewfangled Solutions LLChttp://www.machsupport.com/

‐LinuxCNC (EMC2)http://www.linuxcnc.org/

‐CNC Lite‐CNC Plus

CamSoft(951) 674‐8100http://www.cnccontrols.com/

‐DeskCNC controllerseriall port based controllerIMServicehttp://www.imsrv.com/deskcnc/

Misc. Software

‐Deskengrave (free)Converts TrueType fonts to .dxf drawingshttp://www.deskam.com/deskengrave.html

‐ACE converter (free)Converts .dxf drawings to G‐codehttp://www.dakeng.com/ace.html

‐G‐code to .dxf converter (free)Converts G‐code to .dxf drawingshttp://www.cnczone.com/forums/opensource_software/8814‐g‐code_dxf.html

‐LazyCAM (comes integrated into Mach3)Basic .dxf drawing to G‐code.http://www.machsupport.com/

‐NCPlot (backplotter for G‐code verification)http://www.ncplot.com/

CAD (Computer Aided Design) Software

‐AutoCad‐AutoCad LT‐Inventor (3d CAD)

AutoDeskhttp://usa.autodesk.com/

‐DoubleCAD XTFree AutoCad LT type clone, 2d.http://www.doublecad.com/

‐TurboCADCAM plug‐in availableIMSI/Designhttp://www.turbocad.com/

‐Google SketchUpFree 3d modelerGooglehttp://sketchup.google.com/

‐Rhino3d3d NURBS modelerMcNeel North Americahttp://www.rhino3d.com/

‐Blenderfree 3d modeler, less intuitive than Rhinohttp://www.blender.org/

‐SolidWorks (3D CAD)Dassault Systemeshttp://www.solidworks.com/

CAM (Computer Aided Manufacturing) Software

‐SheetCAM2.5d CAMhttp://www.sheetcam.com/

‐CamBam Plus2.5d, limited 3d CAMhttp://www.cambam.info/

‐PhlatScriptfree 2.5d CAM plug‐in for SketchUphttp://sketchuppluginreviews.com/2010/04/30/phlatscript‐google‐sketchup‐plugin‐review/

‐MeshCAM3d CAM, with indexed 4th axis capabilityhttp://www.grzsoftware.com/landing/

‐Cut2d (2.5d)‐Cut 3d (3d)‐VCarve Pro (V‐carving, 2.5d)‐Photo VCarve (converts images to toolpaths)

http://www.vectric.com/

‐FreeMILL (free basic 3d CAM)‐VisualMill (3d)‐RhinoCAM (plug‐in for Rhino3d)

http://www.mecsoft.com/

‐DeskProto Entry Editionsimple 2.5d, 3dhttp://www.deskproto.com/

‐ArtCAM Express2.5d, 3dhttp://www.artcamexpress.com/

ALUMINUM.1875" x 2.50" x 2.25"

BEARINGS(2) 3/8" x 13/16" x 9/64" unshielded needle bearings, VXB Item# Kit12703(includes hardened washers)

If ordering from a supplier other than VXB, be sure that the twohardened washers are included with bearings.

ALUMINUM or hard plastic, such as ACETAL (delrin).375" x 2.25" x 2.25"

THREADED SHAFT COLLARDelrin threaded collar to match lead‐screw pitch. Source: DumpsterCNCAlternatively, an unthreaded metal split shaft collar may be used. Hoever, thiswill be more difficult to adjust correctly.

FABRICATED PARTSpart # part name # reqd.46 thrust bearing plate 147 z axis motor spacer 1

LIST OF FABRICATED PARTS

BILL OF MATERIALSThe materials for this upgrade are not included in the main Bill ofMaterials on page 27. These quantities should be added to thatprimary Bill of Materials when purchasing metal stock and hardware.Required is:

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171ADDENDUM z axis thrust bearings

Z axis thrust bearing addition:

This addendum covers the installation of a pair of thrustbearing to the Z axis lead‐screw assembly. The originaldesign of the Momus CNC router did not include a thrustbearing for several reasons: they would add to the overallcost of the machine, they add to the height of the Z axiswhile potentially reducing its travel, and require properadjustment in order to be effective. A successful thrustbearing design would not only need to solve these issues,but in keeping with the rest of the design of the machine,would also need to able to be fabricated without specialtools or equipment.

However, there are several strong reasons for includingsuch bearings. They relieve the stepper motor bearings ofall axial force, which is beneficial as they have a lowrating for loads of this type. Therefore, external thrustbearings will potentially increase the longevity of the Zaxis stepper motor. The other reason is that a failure ofthe coupling between the motor and the lead‐screw couldcause the router to plunge into the table. While this typeof failure is unlikely, this thrust bearing upgrade willprovide extra insurance against this happening.

Therefore, it is highly recommended that the followingcomponents be installed on Momus CNC routers. Thisupgrade is fully compatible with all previous versions ofthe machine. However, on machines constructed fromolder versions of the plans, it may reduce the Z axis travelby approximately 7/16", and will also raise the motorvertically by 3/8". This may cause cover interference onolder machines that use quad‐stack stepper motors witha dual shaft. A thin shim between the cover and themachine base can be used to raise it for sufficientclearance.

The assembly sequence shown here was photographedinstalling the parts onto an existing machine. Theassembly sequence is identical on a new machine, onlythe gantry will not yet have been installed on themachine. Combine these instructions with those onpages 131‐132.

20 Z motor mount right (existing)

21 Z motor mount left (existing)

22 Z cable plate (existing)

47 Z axis motor spacer

46 thrust bearing plate

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172ADDENDUM exploded view

2.25

4.5

1.125

2.25

0.375.1875

.438 DIA.

.25 DIA., 4 holes1.8561.856.928 .928

4.5

1.856

1.856

2.25

.9281.125

.928

2.25


1.5

1.5

.75

.75

0.5.25

Slight enlargement of this notchmay be necessary to allow properadjustment of lead‐screw.

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173ADDENDUM thrust bearing plate



# required: 1

2.25

4.5

1.125

2.25

0.75

.375

1.50 DIA.

.25 DIA., 4 holes1.8561.856.928 .928

4.5

1.856

1.856

2.25

.9281.125

.928

2.25


1.5

1.5

.75

.75

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174ADDENDUM z axis motor spacer


material:6061‐T6 alum.OR acetal plastic

# required: 1

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175ADDENDUM thrust bearing assembly

The images to the left and right show the additional lead‐screw components that are not shown in the main plans.

As shown to the left, thread the Delrin collar onto theleadscrew, about 1.5". Slide one unlubricated needle bearing,and its hardened washers, against the top of the collar. Insertthis assembly through the hole in the aluminum thrust bearingplate (part #46). Slide the other unlubricated bearing andhardened washers onto the top of the plate.

As shown to the right, thread the motor coupler onto the end ofthe lead‐screw. Thread it down the screw until the end of thescrew is aligned with the bottom of the slot in the coupler.Gently tighten the coupler in position.

As shown in the left image, thread the collar back up the lead‐screw until it firmly compresses the stack of componentsagainst the coupler. While keeping it firmly threaded againstthe parts, tighten it in position.

Keep the collar tightened in place, and remove the othercomponents from the lead‐screw, as shown to the right.

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Thread the lead‐screw, with the collar installed per theinstructions on the previous page, down through the anti‐backlash nut, as seen in the image to the left. Thread it farenough that the top of the screw is approximately 1" belowthe bottom of the Z motor mounts.

As seen to the right, lightly lubricate one of the needlebearings, and with it sandwiched between its hardenedwashers, slide it down the screw onto the collar. A lightlithium grease can be used for lubricant. Be cautious to notuse an excessive amount, that will get onto the surfaces ofthe collar. The collar should be kept clean.

As shown to the left, temporarily install the aluminum bearingplate with one or two of the 2.5" screws, and place the otherlubricated bearing and washers on its top surface. Make sureits bore is aligned over the hole in the bearing plate.

Raise the Z axis assembly up, so that the end of the lead‐screwis guided through the hole in the bearing plate, and through thebearing. While holding it in this position, thread the motorcoupler onto the end of the screw. Thread it down the screwuntil it is firmly clamping the bearings and plate to the collar.This tightness is the pre‐load setting on the bearings, andshould be tight enough to remove all slack. Maintain thecoupler in this adjustment, and tighten its clamping screws.

Remove the temporary screws holding the bearing plate to themotor mounts.

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Set the new motor spacer (part #47) on top of the motormounts.

Set the cable plate (part #22) on top of the motor spacer.Place the stepper motor into position. Carefully raise the Zaxis assembly up, so that the motor coupler is guided ontothe end of the motor shaft. Be sure to carefully align theflat on the motor shaft with the set screw in the coupler (seepage 131 for the addition of this set screw to the Delrincoupler.) It may take some wiggling to get the coupler toslide onto the shaft.

Install the four screws that hold the motor to the mounts.Tighten them snugly in place.

Fully tighten the clamping screws on the coupler, so thatthe motor shaft is securely held. Tighten the set screwagainst the flat on the motor shaft.

During the alignment procedure described on page 164,very slightly loosen the four screws holding the motor to itsmounts so that the motor can be repositioned side to sidefor proper lead‐screw adjustment. Fully tighten the screwsafter this process. Do not loosen any of the clampingscrews on the coupler or collar during this process, or thebearing pre‐load adjustment may be lost.

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The needle bearings that are used are an unshieldeddesign, that must be protected against dust and cuttingchips. The lower bearing can be protected by merelywrapping a length of PVC electrical tape around thecircumference of the collar. Carefully set it so that it justlightly contacts the bottom surface of the bearing plate.

The upper bearing can be protected by simply closing offthe front of the cavity in which it sits between the motormounts. This can also be done with tape, as shown to theright, or a blockoff plate can be fabricated.

After closing off the cavity, re‐install the Z axis limitswitch. The limit switch placement will need to beadjusted from where it would be placed if no thrustbearings were used. This may mean only one screw willsecure the bracket that is included with these plans.

Momus Design Cnc Router Manual Version 2.1

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Transcript of Momus Design Cnc Router Manual Version 2.1