Chapter 7 Computer-Aided Drafting and Design
159
Moving Objects
It is often necessary to relocate objects after
they are drawn. This can be done with the
Move command. After selecting one or more
objects to move, you must specify a base point
for the selection set. This may be the corner
point of a rectangle or the center point of a
circle. You are then asked for a displacement
point. You can pick a point on screen or enter
coordinates, or you can move the mouse and
enter a distance at the keyboard. The objects
making up the selection set are then moved
automatically to the new location.
Copying Objects
Copying objects is similar to using the
Move command, except the original objects
are not altered by the operation. Objects can
be copied using the Copy command. After
selecting the objects to copy and the base point,
a displacement point is specifi ed. The selected
objects are then copied to the new location.
Depending on the software you are using,
the Multiple option may be active when you
access the Copy command. This option allows
you to copy the original object or selection
set of objects to multiple locations in a single
command sequence.
Rotating Objects
Rotating an object changes the angular
position of the object with respect to the current
orientation. Objects can be rotated using the
Rotate command. When using this command,
the selected objects are rotated about the base
point specifi ed. The objects may be rotated
clockwise or counterclockwise.
If the objects to rotate are already rotated
to a given angle when you enter the Rotate
command, you can enter the angle as a
reference angle. For example, if the objects are
drawn at 45°, enter 45° as the reference angle.
Then, enter the desired angle of rotation.
Scaling Objects
An object can be reduced or enlarged to a
different size by a given scale factor. This is
Hatch patterns are created with the Hatch
command. The fi rst step in creating a hatch
pattern is to select an internal point of the
area to be hatched. An alternative is to select
an object that forms a boundary around the
area to be hatched. After making a selection, a
preview of the hatch pattern appears. At this
point, you can specify a different hatch pattern
or adjust the default settings of the existing
pattern. Options are typically available for
adjusting the hatch pattern scale and angle.
Editing and Modifying
Objects
One of the most important advantages of
a CAD program is the ability to easily modify
objects once they are drawn. Objects can be
moved, copied, rotated, and scaled using the
appropriate commands. These commands
may be identifi ed by the software as editing
commands or modifying commands (or both),
depending on the CAD system you are using.
In addition to these basic commands, there are
a number of other editing methods that can be
used to construct objects. This provides great
fl exibility. Some of the most common editing
and modifying commands in CAD programs
are discussed in the following sections.
Goodheart-Willcox Publisher
Figure 7-17. Hatch patterns are used to represent
materials in section views. The general purpose
section line symbol, used for hatching in this example,
consists of continuous lines drawn at 45° and spaced
approximately .125″ apart.
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