Lesson 1b: Creating a Drawing, Command Entry, Corrections, Objects and
Coordinates
Objectives: at the end of this lesson the user should understand:
1. configuring the workspace
2. the basic process of creating a drawing
3. three best ways to enter a command
4. correcting command errors
5. coordinate system
6. five ways to define coordinates
1. Configuring the workspace
Step-by-step instructions for starting AutoCAD 2012 are given in the instructions for lab
period 2.
AutoCAD 2012 initially begins using the Drafting & Annotation * workspace
as shown in the following figure.
An alternate and still popular workspace is AutoCAD classic which is brought up as
shown in the following figure.
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2. Select AutoCAD Classic
1. Click the
Workspace Switching
icon (Gear) as shown
Selecting AutoCAD Classic changes the workspace to appear as shown in the following
figure.
The textbook uses the Drafting & Annotation workspace
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2. The basic process of creating a drawing
Once AutoCAD is running in Classic workspace mode, one can begin creating a drawing
but first the important areas of the workspace should be noted
4. Command
Headings box
(file ops, and
drawing utilities)
3. Tabs and panels where the
panels contains tools that can
be used to create drawings
such as the line tool
Cursor
1. Drawing area
5. Coordinate display
2. Command line
Eyes move constantly between
drawing area and command line
6. Status line
Drawings are usually started by opening:
* a standard template or
* an existing standard drawing that contains items such as a border and title block.
In this course an existing standard drawing will be opened and is shown in the figure
below.
The procedure to open an MIME 1100 standard drawing, as shown below, will be
explained in detail during the laboratory period.
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To create a drawing, the user enters commands to create entities or objects including
* lines, arcs, circles and other geometric entities.
* and text and dimensions.
The geometry creation commands such as line and circle the require coordinates or
dimensions be entered.
In the sections that follow command entry will be discussed first, followed by
coordinate entry
Commands can also be given to modify or change the entities or objects.
Once the drawing is complete, a hardcopy can be plotted.
As the drawing proceeds, one should periodically save the drawing so all
work is not lost if the system crashes.
3. Three Best Ways to Enter a Command
To create and modify geometry commands are given.
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The easiest three ways to give commands are shown in the following figures with the
command being given to draw a line.
Method 1 select the command from a panel
2. If you pause over the tool
without clicking, explanatory
material appears
1. Click the line tool in the
Home panel begins the
process of creating a line
3. The command line prompts
the user for the next input
required.
4. If dynamic input is on
Prompts and values are displayed near
the cursor. The functioning of this
dynamic input can confuse some
beginning users so it is recommended
to begin by turning this feature off
Method 2 type commands
1. Typing L or LINE, upper
or lower case, followed by a
Space will start a line
2. Where L initially appears is
controlled by the Dynamic Input button
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Method 3 click on toolbars
To display tool bars if using the Drafting and Annotation workspace are shown in the
next figure.
1. Click on View to bring up
the view panel
2. Select Toolbars then AutoCAD
3. The popup menu appears and
you can select toolbars desired such
as Draw and Modify
4. The Draw and Modify toolbars
then appear and commands can be
entered by clicking on their icons
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1. To enter a command click on an icon
2. If you don’t know what the icon means,
pause before clicking and help is displayed.
3. If you pause longer before clicking,
additional help is displayed.
To control what toolbars are displayed right click on any toolbar header and
check/uncheck the toolbars to be displayed/not displayed.
1. Right click on any
toolbar to control which
toolbars are displayed.
2. Clicking on any toolbar name changes status
check = toolbar is displayed,
no check = toolbar is not displayed
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4. Correcting errors in commands
Table 4.1 Error Correcting
Error
Command is wrong and Space or Enter has
not been pushed
Command has been entered and options are
being selected
Command has been completed and result is
not what was desired
Previous work is incorrect
Action
Backspace or delete key – corrects typing
errors
Esc key – deletes all characters on current
command line
Esc key – aborts the command
Typing Undo undoes previous command
Undo 3 undoes the last 3 commands etc.
If too much is undone, Redo will executed
undone commands again.
The Erase command permits geometry to
be selected which are then erased when
Enter is pushed.
5. Coordinate System and Positive Angles
A coordinate system or reference system is required to * dimension and position objects.
AutoCAD uses * a right-handed coordinate system.
y

Note positive direction of
rotation. This will be used
frequently later in the course.
x
z
The coordinate system used to define entities in AutoCAD is referred to as the User
Coordinate System or UCS.
A coordinate system icon can be turned on/off in the drawing area of the window with the
UCSICON command.
6. Five Methods of Specifying the Position of Points
Let’s assume one wishes to draw a rectangle with its lower left corner at 1,1 that is 3
units wide and 2 unit high.
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6.1 Interactive – * simply clicking on points
Trying to watch the coordinates in the lower left corner of the window and clicking at
precisely the correct position is very difficult.
If points are to be enter interactively, usually a grid of points are displayed and the
system is asked to snap to the points. The two relevant commands are
* GRID and SNAP
For example a rectangle that is 3 units wide and 2 units tall is to be drawn with its lower
left corner at x = 1, y = 1.
D
C
A
B
Grid and snap distances
can be the same or
different
Click on Points A, B, C,
D A and then push enter
6.2 Absolute Cartesian – type in coordinates relative to * User Coordinate System, UCS
Format: * x_value,y_value
Example: 3,2
The example below shows the same rectangle that was drawn previously drawn with
absolute coordinates.
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6.3 Relative Cartesian Coordinate – type in coordinates relative to * the current point.
The current point is * the last point that was entered.
Format: * @x_value,y_value Example @3,2
The @ is entered by typing shift 2
The example below shows the same rectangle that was drawn previously drawn with
relative Cartesian coordinates.
First point had to be absolute
coordinates
Enter key was pushed
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6.4 Absolute polar – type in polar coordinates relative to the * UCS.
Polar coordinates are specified by giving a * length and an angle from the +x UCS axis.
Format: * length_value<angle_in_degrees
Example: 2<135
Angles are measured positively in the * counter-clockwise direction.
The rectangle used in previous examples would not normally be created using absolute
coordinates because the lengths and angles would be difficult to compute and would not
be precise.
6.5 Relative polar – type in polar coordinates relative to the * current point.
Format: * @length_value<angle_in_degrees from +x axis
Example: @2<135
The example below shows the same rectangle that was drawn previously drawn with
relative polar coordinates.
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Examples of Absolute and Relative Coordinates
Coordinate Type
Absolute Cartesian
Absolute Polar
Relative Cartesian
Relative Polar
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With Respect To
Origin
Origin
Last Point (for
example assume last
point was at 4,4)
Last Point for
example assume last
point was at 4,4)
Example Point
A
B
C
Characters Typed
3,-2
4<135
@-2,1
D
E
F
G
@2<11
@3<169
@4<191 or @4<-169
@5<-11 or @5<349
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7. Summary: Lesson 1b: Creating a Drawing, Command Entry, Corrections, Objects and
Coordinates
The student should now know the answers to the following questions.

What are the two methods of beginning a drawing? * Using a standard template or
using an existing drawing.

How are drawings created? * Entering commands to define and modify entities and
objects.

What are the three best ways commands can be entered? * picking from panels,
typing letters and using toolbars

How can you correct errors in commands?
Error
Command is wrong and Enter has not been
pushed
Command has been entered and options are
being selected
Command has been completed and result is
no what was desired
Previous work is incorrect
Action
Backspace or delete key – corrects typing
errors
Esc key – deletes all characters on current
command line
Esc key – aborts the command
Typing Undo undoes previous command
Undo 3 undoes the last 3 commands etc.
If too much is undone, Redo will executed
undone commands again.
The erase command permits geometry to be
selected which are then erased when Enter
is pushed.

Many commands involve defining positions and angles. What coordinate system that
is used? * A right-handed coordinate system is used

What is the direction for + angles in a right-handed coordinate system? * in the
direction the fingers on the right-hand point if one rotates from +x to +y

What is the coordinate system called in AutoCAD? * the user coordinate system

There are five ways of defining positions in AutoCAD. What are the five methods
and the format of each method?
* interactive – pick on workspace but most often snap to grid or snap to object.
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* absolute Cartesian – type in x,y coordinates relative to the UCS.
* relative Cartesian – type in x,y relative coordinates, @x,y, to the current point.
* absolute polar – type in polar coordinate, length<angle_in_degrees, relative to
UCS +x axis.
* relative Polar – type in polar coordinates, @length<angle_in_degrees, relative
to the current point and angle relative to +x axis

What does the GRID command do? * turns grid point display on/off and set spacing

What does the GRID button at bottom of window do? * only turns grid display on/off

What does the SNAP command do? * turns snap on/off and allows snap distance to
be set

What does the SNAP button at bottom of window do? * turns snap on/off
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