Autocad 2d Module 14 PDF

8/14/2019 Autocad 2d Module 14 PDF

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Learning Outcomes:

AutoCAD Self-paced Learning Modules

AutoCAD 2DModule 14

Trimming and Extending

When you have completed this module, you wil l be able to:

1. Describe and apply the TRIM and EXTEND commands to shorten and lengthen objects

to meet cutting edges defined by existing objects.

Geometry Lesson

Regular Polygons - Part 1

Apolygon is any plane figure bounded by straight lines. A regular polygon is a polygon that

has equal angles, equal sides and can be inscribed or circumscribed around a circle, seepage 2. AutoCAD has a command to automatically construct polygons. You will learn howto do that in a future module. For now, you will have to construct them with lines which willhelp you learn their geometry. The nine most popular regular polygons are shown in Figure14-1.

Figure 14-1

Regular Polygons

...continued on page 14-2

Trimming and Extending The CAD Guys Ltd. Copyright 1993 - 2007 Module 14
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14 - 2 AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-12

Regular Polygons - Part 1 - Continued

Any regular polygon can be

inscribed in or circumscribedaround a circle as shown using ahexagon in figure 14-2.

It is important to

understand and knowthe geometry involvedto construct thetriangle, square,hexagon, and octagon.as shown in Figure14-3.

An example of drawing

a hexagon in AutoCADis Figure 14-4. Step 1,draw 6 constructionlines from the center 60degrees apart. Step 2,draw six lines snappingto the end of one line tothe end of the next line.Step 3, turn theconstruction layer off.

Figure 14-2

Inscribed and Circumscribed Polygon

Figure 14-3

Geometry of a Polygon

Figure 14-4

Drawing a Hexagon



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AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-12


Since you cannot draw every object using exact coordinates or locations as you have been

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doing in the past labs, you must learn to draw objects to approximate lengths and then trim orextend them to the exact location. This does not mean you can guess at the locations of theobjects. You must still draw them with 100 percent accuracy. You can guess at their length

and then adjust the length with the TRIM or EXTEND commands. These two command are abig part of becoming more productive.

AutoCAD Command: TRIMThe TRIM command is used to shorten objects to meet the edges of other objects. It is notrequired for the object being trimmed to intersect with the object forming the cutting edge.

Shortcut: TR

2004-2008

2000-2002

AutoCAD Command: EXTENDThe EXTEND command is used to lengthen objects to meet the edges of other objects. It is notrequired for the object being extended to intersect with the object forming the cutt ing edge.

Shortcut: EX`

2004-2008

2000-2002

With both the TRIM and EXTEND commands, a very common beginner's

error is picking the wrong objects first. Always select the cutting edgeobject(s) first, press the Enter or the Space key and then select the objectsto be trimmed or extended.

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Using the TRIM and EXTEND Commands

Step 1 Start a new drawing using thetemplate Module Template A

Step 2 Save and name the drawing

AutoCAD 2D Workalong 14-1.

Step 3 Create the layers Object and

Construction, Figure Step 3A, and enterthe commands below to draw the object

shown in Figure Step 3B. Draw on layerConstruction.

Figure Step 3A

Command: L

Specify first point: 2.5,4.5Specify next point or [Undo]: @1,0

Specify next point or [Undo]: @2,0Specify next point or [Close/Undo]: @1,0Specify next point or [Close/Undo]: @0,4

Specify next point or [Close/Undo]: @0,1Specify next point or [Close/Undo]: @-3,0Specify next point or [Close/Undo]: @2


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Using the TRIM and EXTEND Commands - Continued

Step 4 Enter the TRIM command as shown below. See Figures Step 4.

Command: TRIM

Current settings: Projection=UCS, Edge=None

Select cutting edges ...Select objects or : P3 1 foundSelect objects: P4 1 found, 2 total

(These lines are the cutting planes.)Select objects:

(Press enter or space.)Select object to trim or shift-select to extend or

[Fence/Crossing/Project/Edge/eRase/Undo]: P5 Figure Step 4Select object to trim or shift-select to extend or[Fence/Crossing/Project/Edge/eRase/Undo]: P6

(These are the lines to trim. Select the line close to the end to be trimmed.)Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]:Command

Step 5 Enter the EXTEND command shown

below. See Figures Step 5A and 5B.

Command: EXTEND

Current settings: Projection=UCS, Edge=NoneSelect boundary edges ...

Select objects or : P7 1 found Figure Step 5A(The cutting plane line.)

Select objects:(Press enter of space.)

Select object to extend or shift-select to trim or[Fence/Crossing/Project/Edge/Undo]: P8

(The line to extend. Select the line close to the end

that is to be extended.)Select object to extend or shift-select to trim or

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[Fence/Crossing/Project/Edge/Undo]:Command

Step 6 Draw three construction lines starting at the

midpoint of the bottom line. See Figures Step 6

Command: LSpecify first point: (mid) P9Specify next point or [Undo]: @0,1

Specify next point or [Undo]: @0,1.5Specify next point or [Close/Undo]: @0,1.5

Specify next point or [Close/Undo]:Command:


Figure Step 5B

Figure Step 6



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Step 7 Enter the commands below to insert the construction lines for the hexagon, Draw

6 lines all starting from the end of the construction line as shown in Figure Step 7.

Command: L

Specify first point: (end) P10Specify next point or [Undo]: @.5


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Step 9 Enter the commands shown below to draw the slot as shown in Figure Step 9A

and 9B.

Command: L

Specify first point: (end) P17Specify next point or [Undo]: @1,0Specify next point or [Undo]:Command: LSpecify first point: (end) P17Specify next point or [Undo]: @-1,0Specify next point or [Undo]:Command: CSpecify center point for circle or [3P/2P/Ttr (tan tan

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radius)]: (end) P18Specify radius of circle or [Diameter]: D

Specify diameter of circle: .5Command: C

Specify center point for circle or [3P/2P/Ttr (tan tanradius)]: (end) P19Specify radius of circle or [Diameter] :Command: LSpecify first point: (quad) P20

Specify next point or [Undo]: (quad) P21Specify next point or [Undo]:Command: LSpecify first point: (quad) P22

Specify next point or [Undo]: (quad) P23Specify next point or [Undo]:Command:

Figure Step 9A

Figure Step 9B

Step 10 Enter the commands shown below to draw the bottom arc asshown in Figure Step 10A and 10B.

Command: CSpecify center point for circle or [3P/2P/Ttr (tan tan radius)]: (end) P24Specify radius of circle or [Diameter]: D

Specify diameter of circle: 1Command: LSpecify first point: (cen) P25

Specify next point or [Undo]: (end) P26Specify next point or [Undo]:Command: LSpecify first point: (cen) P25

Specify next point or [Undo]: (end) P27Specify next point or [Undo]:Command:

Figure Step 10A



Figure Step 10B

The CAD Guys Ltd. Copyright 1993 - 2007 Module 14


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Step 11 Enter the TRIM command shown

below to create the slot as shown in FigureStep 11A and 11B.

Command: TRIM

Current settings: Projection=UCS, Edge=NoneSelect cutting edges ...Select objects or : P28 1 foundSelect objects: P29 1 found, 2 totalSelect objects:

(Press enter or space.)Select object to trim or shift-select to extend or[Fence/Crossing/Project/Edge/eRase/Undo]: P30Select object to trim or shift-select to extend or[Fence/Crossing/Project/Edge/eRase/Undo]: P31

Select object to trim or shift-select to extend or[Fence/Crossing/Project/Edge/eRase/Undo]:

Command:

Step 12 Enter the TRIM command shown below to

create the bottom arc as shown in Figure 12A, 12B and12B.

Command: TRIM

Current settings: Projection=UCS, Edge=NoneSelect cutting edges ...Select objects or : P32 1 found

Select objects: P33 1 found, 2 totalSelect objects: P34 1 found, 3 totalSelect objects:

(Press enter or space)Select object to trim or shift-select to extend or[Fence/Crossing/Project/Edge/eRase/Undo]: P35

Figure Step 11A

Figure Step 11B

Figure Step 12A

Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]: P36


Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]:Command:

Figure Step 12B

Figure Step 12C




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Step 13 Enter the TRIM command shown below to

trim the line on the top right as shown in Figure Step13.

Command: TRIM

Current settings: Projection=UCS, Edge=NoneSelect cutting edges ...

Select objects or : P38 1 found

Select objects: Figure Step 13(Press enter or space)

Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]: P39Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]:Command:

Step 14 Select the

objects that you want toreside on layer Object.While the objects areselected, pull down thelayer toolbar and clickthe name Object asshown in Figure Step14.

Figure Step 14

Step 15 Freeze layer Construction.

Step 16 The drawing is complete and should

appear as shown in Figure Step 16.

Step 17 Save and close the drawing.

Figure Step 16

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The TRIM and EXTEND commands areinterchangeable. If you enter eithercommand, you can change over to theother command by holding down the Shiftkey. For example:

Command: TRIM (See Figure Step 1.)Current settings: Projection=UCS, Edge=NoneSelect cutting edges ...Select objects or : P1 1 foundSelect objects: P2 1 found, 2 total

Select objects: P3 1 found, 3 totalSelect objects: P4 1 found, 4 totalSelect objects:

Figure Step 1

Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]: E(Enter the Edge option.)

Enter an implied edge extension mode [Extend/No extend] : E(Set to Extend. This allows you to trim or extend when the objects do not physically touch.)

Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]: P5Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]: P6


(Press and hold down the shift key to change to the EXTEND command.)Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]: P8


Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]: P10Select object to trim or shift-select to extend or [Fence/Crossing/Project/Edge/eRase/Undo]:Command:

Figure Step 2 Completed Drawing

The Key Principles in Module 14

1. To speed the drawing process, draw the location and direction of objects with 100

percent accuracy but enter an arbitrary length. Then, adjust the length with the TRIM orEXTEND commands.

2. With both the TRIM and EXTEND commands, select the cutting edge objects first, then

press the Enter or the Space key and then select the object(s) to trim or extend.

3. The TRIM and EXTEND commands are interchangeable by holding down the shift key to

change from one command to the other.



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AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-12 14 - 11

Lab Exercise 14-1

Drawing Specifications

Time Allowed: 30 Min.

Name Template Units Text Style Font

AutoCAD 2D Lab 14-1 Module Template A Inches N/A N/A

Note: Color, Linetype, and Lineweight are all < ByLayer< unless otherwise instructed.

Layering Scheme

Objects on Layer Name Color Linetype Lineweight

Construction Objects

All Objects

Instructions:

Construction

Object

253

Red

Continuous

Continuous

N/A

N/A

1. Setup the layers using the Layering Scheme shown above.2. Draw the object shown below using the layering scheme above.3. Draw all construction objects on layer Construction.4. Check your drawing with the key.

5 If you have any errors, correct your drawing.6. Turn layer Key off and freeze layer Construction.7. Save and close the drawing.

Completed

Drawing



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Construction Techniques

The following steps are the construction technique suggested by the author to help you learn

how to construct objects using AutoCAD. It is only the suggested method and if you cancomplete the drawing accurately using a different construct technique, that is what is important.You may want to compare your construction technique with the authors.

Construction Hints

Do your best to complete the lab exercise drawing without using the

following hint(s). If you get stuck and can't complete it on your own,use the following hint(s) to help you.

Hint 1

Draw the lines in the correct

location and direction but to anylength and then trim or extendthem.


Hint 2

The lines in Figure Hint 2A must beFigure Hint 1

drawn tangent to tangent (see Module 12) while the lines in Figure Hint 2B can be draw eithertangent to tangent or quad to quad.

Figure Hint 2AFigure Hint 2B



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Lab Exercise 14-2

Drawing Specifications

Time Allowed: 30 Min.

Name Template Units Text Style Font

AutoCAD 2D Lab 14-2 Module Template A4 Millimeters N/A N/A

Note: Color, Linetype, and Lineweight are all < ByLayer< unless otherwise instructed.

Layering Scheme

Objects on Layer Name Color Linetype Lineweight


Outside Circle

Inside Circles

Slots

Instructions:

Construction

Circle 1

Circle 2

Slot

253

Green

Red

Blue

Continuous

Center 2

Continuous

Dashdot 2

N/A

N/A

N/A

N/A

1. Setup the layers using the Layering Scheme shown above.

2. Draw the object shown below using the layering scheme above.3. Draw all construction objects on layer Construction.4. Check your drawing with the key.5 If you have any errors, correct your drawing.6. Turn layer Key off and freeze layer Construction.7. Save and close the drawing.

Completed

Drawing



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Construction Techniques

The following steps are the construction technique suggested by the author to help you learn

how to construct objects using AutoCAD. It is only the suggested method and if you cancomplete the drawing accurately using a different construct technique, that is what is important.You may want to compare your construction technique with the authors.

Construction Hints

Do your best to complete the lab

exercise drawing without using the

following hint(s). If you get stuck andcan't complete it on your own, use thefollowing hint(s) to help you.

Hint 1

Only draw four of the lines as

shown in Figure Hint 1. Thenextend them to other side of thelarge circle. That will save youdrawing 8 lines.

Hint 2

Figure Hint 2A - Draw 8 circles with

their center at the intersection of thelines and circles.

Figure Hint 2B - Draw 2 large circles.

Figure Hint 2C - Trim the large circles.

Figure Hint 2D - Trim the slots.

Figure Hint 1

Figure Hint 2A

Figure Hint 2C


Figure Hint 2B

Figure Hint 2D


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