Page 65 - Engineering drawing from first principles using AutoCAD

58 Enqineerinq drawinq [rom first principles

UNDO, REDO BREAK, EXTEND and TRIM features

When engaged on constructional and design work it is necessary to modify drawings, and
this involves editing linework. You will also find that when you change one item, there is
invariably a knock-on effect and further changes are required. Modifications to existing
drawings are a large part of the draughtsman's work. It will often be possible to take an
existing drawing, delete a few lines, add a few lines, change a few notes and a satisfactory
new drawing is the result.
The UNDO feature is a blessing. We all make mistakes, but fortunately the computer
remembers each step we make, as we make them, and these can be methodically undone.
If the command line reads Command:, Click on Undo in the Edit menu and the
command line reads

Command: _U
GROUP
Command:

Press <Enter> and the last drawing operation will disappear from the screen. The com-
mand line now reads

U GROUP
Command:

L3 L3 L3

L1 L1 L1
L2 L2 L2

(i)

L3 L3 L3

L1 L1 L1
L2 L2 L2

(iv)

Figure 2.28