3D Printing

Turning molten plastic into neat toys

3D Printing

• Lots of different kinds of 3d printing• Some use powder, metal, etc.• Primary home/hobby printing is “FDM” –

Fused Deposition Modelling– Basically: A glue gun controlled by a printer– Assembly is layer-by-layer

Models: Makerbot

• Consumer-targeted 3d printer

• Designed to be ‘no setup’; easy for consumers

• Costs about $2200

Models: Printrbot

• Originally kickstarter• Typically sold as kits

(but can buy assembled for $100)

• Varies in cost from $300-$800

• Targeted at hobbyists.

Materials

• PLA– Biodegradable– Produced from corn– Lower melting temperature (compared to ABS)

• ABS– Higher temperature– Higher melting temperature

• Can print in other things (teflon; nylon; wood filament) – much less common (and more expensive)

Costs

• “Filament” (plastic used as input to the printer) typically costs about $30/kg– Can be found as low as $20, but “you get what

you pay for”

• Many small items can be made for 50 cents or so worth of plastic

What can you make?

• Just about anything plastic with enough care• Limited by build volume (Printrbot Plus is 8”

cube) and layering approach– You aren’t going to build a car with a 3d printer

very quickly– You’re also not going to build a chandelier very

easily – anything with overhangs can be difficult

How it works: Software

• Take a 3D model (STL file)• Use a ‘slicer’ to turn it into layered paths for

the head of the printer• Slicer intelligently fills in solid spaces with

material – Also tries to minimize plastic on the insides of

pieces so as to not waste material

How it works: G-Code• Slicer generates “G-Code”

– a set of “move here, at this rate” instructions

• G-Code was originally designed in the 1980s for driving other computer-driven manufacturing

• G-Code can be interpreted by firmware on the electronics attached to the printer

How it works: Repetier

• Software to control overall interactions with the printer

• Communicates over USB to printer

• Has UI to control position, heat, fan, etc.

• Repetier also has slicing and G-Code visualization

How it works: Printing

• Melts 3D plastic in a heated head (~200 degrees C)

• Prints onto flat surface – important to get the first layer right so it sticks

• Motor feeds material through the hot end, pushing plastic out the other side.

• Motors move the bed and the print head in 3 dimensions to print

How it works: Complex Prints

• Some 3D models can’t be printed without overhangs

• Two basic components: Bridges and support material

• Bridges are connections between two existing pieces of plastic

• Support material is thin layers designed to form a basis for bridges – temporary, intended to snap-away

How it works: Complex Shapes

• Not all complex shapes are complex prints though

• Some shapes with lots of holes in them can still be printed (relatively) easily

• Common style: Voronoi surface

How it works: Bigger Shapes

• 3d printing bigger shapes usually works via snap-fit or press-fit pieces

• Push pieces together to get them to stay

Coolest Items

• Articulated excavator: “Little Digger”, thing:208315

• Prints as one piece• Wheels, cab, and arm

move

Coolest Items

• Fidget cubes• Prints as one piece• Hinged• thing:230139

Finding Models: Thingiverse

• Thingiverse is a 3d model repository that offers lots of 3d models

• Social – can also share 3d models, share ‘makes’, etc.

• Supported by Makerware• Good to find first things to print – toys,

puzzles, printer improvements…

Designing Models: OpenSCAD

• OpenSCAD is 3D Modeling for programmers

• You write 3D models with code

• Can import and export common formats

Designing Models: Sketchup

• Sketchup – formerly from Google – is another design tool

• Free plugin to support export to STL• Can be used as a visual design tool (rather

than code)

Creating your own Filament

• Filament extruders can be purchased as kits for a few hundred $

• Take in plastic pellets ($7-$10/kg instead of $30-$40)

• No commonly available way to re-melt prints currently, but people are working on recyclers

Other types of 3D Printing

• Powder bed 3d printing• Laser sintering• Laminated• Light Polymerized

Things to know• 3D Printers – at least, printrbot – is *not* a

commercially ready tool– It requires a lot of tinkering and tweaking to get good

prints– When the answer from support to a problem is “Pull

out your multimeter and measure the resistance” you know you’re in a hobbyist market

• If you buy a kit – expect it to take a while to build• Bed level is important: Bed level and belt tension

are the two most important aspects of good prints

FAQ

• Have you printed a gun?– No. This is a silly use of 3d printing, there are lots

of easy ways to build your own gun.

• How long have you had it?– About two weeks

• Is it made of wood?– Yep