Chapter 4 CAD Commands and Functions 109
AutoCAD Example:
Command: erase↵
Select objects: last↵
1 found
Select objects: ↵
(or pick other objects on screen)
Command:
Undo
The
Undo
command reverses the last com-
mand. If the last command was Erase, the
objects that were deleted are restored. You can
sequentially step back through previous com-
mands, but you cannot “jump” a command in
the sequence. Certain limits are usually applied
to this command.
AutoCAD Example:
Command: erase↵
Select objects: last↵
1 found
Select objects: ↵
(the last object drawn is erased)
Command: undo↵
Current settings: Auto = On, Control = All, Combine
= Yes
Enter the number of operations to undo or [Auto/
Control/BEgin/End/Mark/Back] 1: ↵
ERASE
(the erased object is restored)
Command:
Move
The
Move
command allows one or more
objects to be moved from the present location to
a new one without changing their orientation or
size. Generally, you must pick a starting point
and a destination point. Relative displacement
is often used for this operation. With relative
displacement, you pick any starting point. Then,
you specify a displacement from that point in
terms of units, or units and an angle.
AutoCAD Example:
Command: move↵
Select objects:
(pick any number of objects using the
cursor)
Select objects: ↵
Specify base point or [Displacement] Displacement:
(pick any point on screen)
Specify second point or use fi rst point as
displacement: @2,3
(the
@
symbol specifiesfi
relative displacement; the object will be moved 2
units on the X axis and 3 units on the Y axis)
Command:
Copy
The
Copy
command usually functions in
much the same way as the
Move
command.
However, it is used to place copies of the selected
objects at the specified location without altering fi
the original objects. Many CAD programs offer
a “multiple” option with this command. This
option is sometimes the default option and
allows multiple copies of the selected objects to
be placed in sequence.
AutoCAD Example:
Command: copy↵y y
Select objects: (select the objects to copy)
Select objects: ↵
Specify base point or [Displacement] Displacement:
(enter coordinates or pick a point to use as the first fi
point of displacement)
Specify second point or use fi rst point as
displacement:
(enter coordinates or pick a second
point of displacement for the first copy) fi
Specify second point or [Exit/Undo] Exit:
(enter
coordinates or pick a second point of displacement
for the second copy)
Specify second point or [Exit/Undo] Exit:
(enter
coordinates or pick a second point of displacement
for the third copy)
Specify second point or [Exit/Undo] Exit: ↵
Command:
Mirror
The
Mirror
command draws a mirror image
r
of an existing object about a centerline. This
command is especially useful when creating
symmetrical objects, Figure 4-13. The
Mirror
command in most CAD programs allows you to
either keep or delete the original object during
the operation. The mirror line can generally be
designated.