AutoCAD Self-paced Learning Modules
®
AutoCAD 2D
Module 4
Drawing Lines Using Cartesian Coordinates
Learning Outcomes:
When you have completed this module, you will 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 Coordinate
System 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 on
a plane. Each coordinate location consists of a pair of numbers, the first of which is the
X-coordinate and the second is the Y-coordinate, written (X,Y). For example, (2,4) is a location
2 units to the right and 4 units up
from X0,Y0.
Cartesian coordinates can be
entered into AutoCAD as either
absolute or relative coordinates.
Absolute Cartesian
Coordinates
Absolute Cartesian coordinates
are always referenced to the
absolute origin 0,0. For example:
3,4.
Relative Cartesian
Coordinates
Relative Cartesian coordinates
are incremental to the last input
point. To indicate to AutoCAD
that it is a relative coordinate you
are referring to, enter an @
before the coordinate. For
example: @2,6
Drawing lines Using Cartesian Coordinates
Figure 4-1
The Cartesian Coordinate System
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4
4-2
AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
Whenever possible, always draw in the
positive quadrant. In almost all cases, X0,Y0
should be the bottom left hand corner of your
6
+Y
5
4
3
2
trimmed drawing.
+X
-X
-6
X 0,Y01
-5
-4
-3
-2
-1
1
2
3
4
5
6
-1
-2
-3
-4
-5
-6
AutoCAD Command:
-Y
LINE
The LINE command is used to draw lines.
Shortcut: L
2004-2008
2000-2002
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, you
must 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 be
too 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 the
exercises in this manner will help you understand how the commands you
are 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 the
lab exercises at the end of each module, you should be able to complete
them without any assistance.
Drawing lines Using Cartesian Coordinates
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4
AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
4-3
Using the LINE Command
Workalong and complete the steps below.
Step 1 Using the NEW command, start a new drawing using the
template 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
Completed
Drawing
Step 3 Enter the commands below to draw the object shown. Keep in
mind that you enter what is bolded, the italics are the author's comments and all the rest
are AutoCAD prompts.
Command: LINE
Specify first point: 1.75,4
(Always start with an absolute coordinate. It must
be 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]: @0,2
Specify next point or [Close/Undo]: @-2.5,0
(A negative coordinate is used since the line is
going in the negative X direction.)
Specify next point or [Close/Undo]: @0,1.5
Specify next point or [Close/Undo]: @-1,1
(When both the X and Y coordinates have a value
other then zero, the line will be inclined.)
Specify next point or [Close/Undo]: @-1.5,0
Specify next point or [Close/Undo]: C
You can use a C or 1.75,4 to close the last line and
return 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 drawing
is 100% accurate. On the object shown
on the right, there are two correct ways to
draw the last line. 1. C (to close) or 2.The
absolute coordinate 1.75,4 The relative coordinate should
never be used since you can't be positive it will locate the
end of the line at the exact location as the start point.
Drawing lines Using Cartesian Coordinates
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4
4-4
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 the
template 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.
Completed
Drawing
Command: L
(L is the shortcut for the LINE command)
Specify first point: 7,5
Specify next point or [Undo]: @0,2
Specify next point or [Undo]: @-2,0
Specify next point or [Close/Undo]: @.75,1
(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]: @-3.5,0
Specify 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,-1
Specify next point or [Close/Undo]: @-2,0
Specify next point or [Close/Undo]: @0,-2
Specify next point or [Close/Undo]: @1,0
Specify next point or [Close/Undo]: @0,.5
Specify next point or [Close/Undo]: @4,0
Specify 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:
Step 4
Save and close the drawing.
Drawing lines Using Cartesian Coordinates
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4
AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
4-5
When you are entering decimal numbers and your number ends in a zero,
for example 4.0, just enter the number up to the zero. In this case, 4. If the
number 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
select it using the pickbox on the graphic cursor.
Move the cursor and when the pickbox is on the
object as shown in Figure 4-2, press the left
mouse button to select it. A selected object will
highlight (dash) and display grip markers as
shown in Figure 4-3. You can select more then
one object at the same time as shown in Figure
4-3. In future modules, you will be shown much
more sophisticated methods of selecting objects.
For now, use the pick method. To unselect an
object(s), press the Esc key. Sometimes you
Figure 4-4
Three Selected Lines have to press it twice.
AutoCAD Command:
Figure 4-2
The Pickbox
on a Line
Figure 4-3
A Selected Line
ERASE
The ERASE command is used to permanently remove objects from the drawing.
Shortcut: E
2004-2008
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 the
objects, you can select them when prompted by the Select Object prompt as shown below.
Command: ERASE
Select Object:
Drawing lines Using Cartesian Coordinates
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Module 4
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AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
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
Workalong and complete the steps below.
Step 1 Open the drawing AutoCAD 2D Workalong 04-1 that you
completed in the workalong on Page 4-3 of this module. If you did not
complete that workalong, do it first.
Step 2 Using the SAVEAS command, save the drawing with the name
AutoCAD 2D Workalong 04-3.
Completed
Drawing
Step 3 Select the three lines shown in Figure Step 3A. Using the
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.
Step 5
Save and close the drawing.
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.
Drawing lines Using Cartesian Coordinates
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4
AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
Lab Exercise 4-1
4-7
Time Allowed: 30 Min.
Drawing Specifications
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
Lineweight
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 Exercises
3. Draw the object shown below.
4. Check your drawing with the key. The key name is the same as the drawing
name 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.
Drawing lines Using Cartesian Coordinates
AUTOCAD SELF-PACED LEARNING MODULES
DRAWN
The CAD Guys Ltd. Copyright © 1993 - 2007
DATE
SCALE
DRAWING NO.
SHEET
Completed
Drawing
Module 4
4-8
AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
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.
Drawing lines Using Cartesian Coordinates
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4
AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
Lab Exercise 4-2
4-9
Time Allowed: 30 Min.
Drawing Specifications
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
Lineweight
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 Exercises
3. Draw the object shown below.
4. Check your drawing with the key. The key name is the same as the drawing
name 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.
AUTOCAD SELF-PACED LEARNING MODULES
DRAWN
DATE
SCALE
DRAWING NO.
SHEET
Completed
Drawing
Drawing lines Using Cartesian Coordinates
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4
4 - 10
AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11
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.
Drawing lines Using Cartesian Coordinates
The CAD Guys Ltd. Copyright © 1993 - 2007
Module 4