Graphics Programs Reference
In-Depth Information
When you want to dimension something in AutoCAD, you can either select the object,
such as a line or polyline segment, or select points on that object, such as the endpoints
of the line or polyline segment. If you select an object, AutoCAD finds the most obvious
points on it to dimension, such as the endpoints of a line. If you choose to select indi-
vidual points instead, use object snaps (see Chapter 7). When you change the size of the
object (for example, by stretching it), AutoCAD automatically moves the dimension's
origin points and updates the dimension text to show the new length.
If you don't use object snaps or another AutoCAD precision technique to
choose dimension points, the dimension text probably won't reflect the precise
measurement of the object. This lack of precision can cause serious problems.
When in doubt, OSNAP to it!
When you set up a new drawing and you want to use annotative dimensions, make sure
the Annotative box is selected on the Fit tab in the New/Modify Dimension Style dialog
box (refer to Figure 14-7). For a new drawing with non-annotative dimensions, change
the Use Overall Scale Of setting on the Fit tab so that it matches the drawing scale
factor. Before you draw any dimensions in a drawing that you didn't set up, check this
setting to make sure it's correct.
The AutoCAD dimensioning commands prompt you with useful information at
the command line or dynamic-input prompts. Read the prompts during every step
of the command, especially when you're trying a dimensioning command for the
first time.
Lining up some linear dimensions
You can ind the iles I use in this sequence of steps at this topic's companion
web site. Go to www.dummies.com/go/autocad2012fd and download afd14.zip .
The drawing named afd14a.dwg contains the mechanical part shown in Figure
14-1.
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