autocad 2d module 04 pdf

8/14/2019 Autocad 2d Module 04 PDF

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AutoCAD Self-paced Learning Modules

AutoCAD 2DModule 4

Drawing Lines Using Cartesian Coordinates

Learning Outcomes:

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

1. Describe the Cartesian Coordinate System using absolute and relative coordinates.

2. Describe and use the LINE command to draw lines using the Cartesian CoordinateSystem with both absolute and relative coordinates.

The Cartesian Coordinate System

To draw accurately in an AutoCAD 2 Dimensional (2D) drawing, you must supply locations by

entering XY coordinates. The 2D coordinates are based on the Cartesian Coordinate System.

The Cartesian Coordinate System consists of two numbered lines crossing perpendicular to

each other at their zero values. The horizontal axis is called the X-axis, and the vertical axis is

called the Y-axis as shown in Figure 4-1. This allows you to assign a value to each location ona plane. Each coordinate location consists of a pair of numbers, the first of which is theX-coordinate and the second is the Y-coordinate, written (X,Y). For example, (2,4) is a location2 units to the right and 4 units upfrom X0,Y0.

Cartesian coordinates can beentered into AutoCAD as either

absolute or relative coordinates.

Absolute Cartesian

Coordinates

Absolute Cartesian coordinates

are always referenced to theabsolute origin 0,0. For example:3,4.

Relative Cartesian

Coordinates

Relative Cartesian coordinates

are incremental to the last inputpoint. To indicate to AutoCADthat it is a relative coordinate youare referring to, enter an @before the coordinate. Forexample: @2,6

Figure 4-1The Cartesian Coordinate System

Drawing lines Using Cartesian Coordinates The CAD Guys Ltd. Copyright 1993 - 2007 Module 4


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4 - 2 AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11

Whenever possible, always draw in the 6

positive quadrant. In almost all cases, X0,Y05

4

should be the bottom left hand corner of your 32

trimmed drawing. -X X 0,Y01

+Y

+X

-6 -5 -4 -3 -2 -1 1 2 3 4 5 6

-1

-2

-3

-4

-5

AutoCAD Command: LINE

-6 -Y

The LINE command is used to draw lines.

Shortcut: L

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If you are entering a positive number in AutoCAD, just enter the number on

it's own. Positive is the AutoCAD default. If the number is negative, youmust enter the - sign before the number. For example, if the number is 4.0,enter 4. If the number is -4.0, enter -4.

When you start a drawing, the first XY location is always specified using an

absolute coordinate. After that, relative coordinates are used. It would betoo difficult to calculate all coordinates as absolute.

When you see the Workalong icon, as shown on the left, workalong with the

modules, tutorial style, to complete the exercise that follows. Completing theexercises in this manner will help you understand how the commands youare being taught in that module work by actually using them in AutoCAD.This will prepare you so that when you are completing the drawings in thelab exercises at the end of each module, you should be able to completethem without any assistance.



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

Using the LINE Command

Workalong and complete the steps below.

Step 1 Using the NEW command, start a new drawing using thetemplate Module Template A.

Step 2 Save and name the drawing AutoCAD 2D Workalong 04-1 and

save it in the folder: CAD Courses/AutoCAD 2D/Lab Exercises

Step 3 Enter the commands below to draw the object shown. Keep in

Completed

Drawing

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mind that you enter what is bolded, the italics are the author's comments and all the restare AutoCAD prompts.

Command: LINE

Specify first point: 1.75,4(Always start with an absolute coordinate. It mustbe an X then Y with a comma between them.)

Specify next point or [Undo]: @5,0(Then change to relative coordinates. Note the @

first, then X and Y.)Specify next point or [Undo]: @0,2Specify next point or [Close/Undo]: @-2.5,0

(A negative coordinate is used since the line isgoing in the negative X direction.)

Specify next point or [Close/Undo]: @0,1.5Specify next point or [Close/Undo]: @-1,1

(When both the X and Y coordinates have a valueother then zero, the line will be inclined.)

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

You can use a C or 1.75,4 to close the last line andreturn to the first point.)Command:

Step 4 Save and close the drawing.

It is important when inserting the final line

of a series of lines to ensure your drawingis 100% accurate. On the object shownon the right, there are two correct ways todraw the last line. 1. C (to close) or 2.The

absolute coordinate 1.75,4 The relative coordinate shouldnever be used since you can't be positive it will locate theend of the line at the exact location as the start point.



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Using the LINE Command


Step 1 Using the NEW command, start a new drawing using thetemplate Module Template A.

Step 2 Save and name the drawing AutoCAD 2D Workalong 04-2 and save

it in the folder: CAD Courses/AutoCAD 2D/Lab Exercises

Step 3 Enter the commands below to draw the object shown.

Command: L

(L is the shortcut for the LINE command)

Specify first point: 7,5Specify next point or [Undo]: @0,2Specify next point or [Undo]: @-2,0Specify next point or [Close/Undo]: @.75,1

Completed

Drawing

(You can draw an inclined line by entering a number other then zero for both the X and Y.)Specify next point or [Close/Undo]: @-3.5,0Specify next point or [Close/Undo]: @-.75,-1

Specify next point or [Close/Undo]: U(When you make an input error, enter a U to go back one step. More than one U can be entered to

step back further. Ensure you press the ENTER or SPACE after each one.)Specify next point or [Close/Undo]: @.75,-1Specify next point or [Close/Undo]: @-2,0

Specify next point or [Close/Undo]: @0,-2Specify next point or [Close/Undo]: @1,0Specify next point or [Close/Undo]: @0,.5

Specify next point or [Close/Undo]: @4,0Specify next point or [Close/Undo]: @0,-.5

Specify next point or [Close/Undo]: 7,5(The object was closed by entering the absolute coordinate.)Specify next point or [Close/Undo]:Command:




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

When you are entering decimal numbers and your number ends in a zero,

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for example 4.0, just enter the number up to the zero. In this case, 4. If thenumber you are entering is 3.6700, all you are required to enter is 3.67.

Deleting Objects

To delete existing objects on a drawing, you can either use the ERASE

command or the Delete key on the keyboard.

Selecting Objects

Before you can delete an object(s), you must

Figure 4-4

Three Selected Lines

select it using the pickbox on the graphic cursor.Move the cursor and when the pickbox is on theobject as shown in Figure 4-2, press the leftmouse button to select it. A selected object willhighlight (dash) and display grip markers as

shown in Figure 4-3. You can select more thenone object at the same time as shown in Figure4-3. In future modules, you will be shown much

more sophisticated methods of selecting objects.For now, use the pick method. To unselect anobject(s), press the Esc key. Sometimes youhave to press it twice.

Figure 4-2

The Pickboxon a Line

Figure 4-3

A Selected Line

AutoCAD Command: ERASEThe ERASE command is used to permanently remove objects from the drawing.

Shortcut: E

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2000-2002

Using the ERASE Command

When you delete objects using the ERASE command, the objects can either be selected

before or after the command is entered. If you enter the command before selecting theobjects, you can select them when prompted by the Select Object prompt as shown below.

Command: ERASE

Select Object:



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Using the Delete Key

When you delete objects using the Delete key, you must select the object(s) first and then

press the key.

Using the ERASE Command


Step 1 Open the drawing AutoCAD 2D Workalong 04-1 that youcompleted in the workalong on Page 4-3 of this module. If you did notcomplete that workalong, do it first.

Step 2 Using the SAVEAS command, save the drawing with the name

AutoCAD 2D Workalong 04-3.

Step 3 Select the three lines shown in Figure Step 3A. Using the

CompletedDrawing

ERASE command, erase them. Your drawing should now appears as shown in Figure

Step 3B.

Step 4 Select the remaining four lines as shown in Figure Step 4. Delete them by

pressing the Delete key on the keyboard.


Figure Step 3A Figure Step 3B Figure Step 4

The Key Principles in Module 4

1. The @ symbol means "The last absolute coordinate location".

2. To close the last line of a series of lines, use either C (Close) or the absolute coordinate

of the first point.

3. To delete existing objects on a drawing, you can either use the ERASE command or the

Delete key on the keyboard.

4. Objects can either be selected before or after the command is entered.

5. To unselect an object(s), press the Esc key. Sometimes you have to press it twice.



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AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11 4 - 7

Lab Exercise 4-1

Drawing Specifications

Time Allowed: 30 Min.

Name Template Units Text Style Font

AutoCAD 2D Lab 04-1 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

N/A

Instructions:

1. Start a new drawing using the template shown above.2. Save and name the drawing AutoCAD 2D Lab 04-1 in the folder:

CAD Courses/AutoCAD 2D/Lab Exercises3. Draw the object shown below.

4. Check your drawing with the key. The key name is the same as the drawingname shown above. If you have trouble doing this, redo Module 3.

5. If you have any errors, correct your drawing.6. Save and close the drawing.

Lineweight

AUTOCADSELF-PACED LEARNINGMODULES

DRA WN DATE S CALE DRA WING NO. SHEET

Completed

Drawing



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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

Figure Hint 1

Hint 2 After you insert the key to check your drawing and you have to correct your drawing,

you can remove the key by deleting it and then reinserting it after you make the corrections.



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AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11 4 - 9

Lab Exercise 4-2

Drawing Specifications

Time Allowed: 30 Min.

Name Template Units Text Style Font

AutoCAD 2D Lab 04-2 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

N/A

Instructions:

1. Start a new drawing using the template shown above.2. Save and name the drawing AutoCAD 2D Lab 04-2 in the folder:

CAD Courses/AutoCAD 2D/Lab Exercises3. Draw the object shown below.

4. Check your drawing with the key. The key name is the same as the drawingname shown above. If you have trouble doing this, redo Module 3.

5. If you have any errors, correct your drawing.6. Save and close the drawing. DRAWN

Lineweight

AUTOCADSELF-PACED LEARNINGMODULES

D ATE SC ALE DR AWING N O. SH EET

Completed

Drawing



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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

Figure Hint 1

Hint 2 After you insert the key to check your drawing and you have to correct your drawing,

you can remove the key by deleting it and then reinserting it after you make the corrections.


autocad 2d module 04 pdf

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