Mark Middlebrook - AutoCAD 2005 for Dummies

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, make sure that you change the Use Overall Scale Of setting on the Fit tab in the New/Modify Dimension Style dialog box 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 dimension drawing commands prompt you with useful information at the command line. Read the command line prompts during every step of the command, especially when you’re trying a dimensioning command for the first time.

Linear dimensions are the most common type of dimensions, and horizontal and vertical are the most common of those. The following example demonstrates all the important techniques for creating horizontal and vertical linear dimensions, as well as aligned dimensions (which are similar to linear dimensions):

1. Use the LINE command to draw a nonorthogonal line — that is, a line segment that’s not horizontal or vertical.

An angle of about 30 degrees works well for this example.

If you want to apply dimensioning to an object other than a line, use these steps as a general guideline, filling in the appropriate commands and data as applicable to your drawing.

2. Set a layer that’s appropriate for dimensions current.

See Chapter 4 for details.

3. Set a dimension style that’s appropriate for your needs current.

Choose an existing dimension style from the Dim Style Control drop-down list on the Styles toolbar, or create a new style by using the procedure in the section, “Creating and managing dimension styles,” earlier in this chapter.

4. Choose Dimension→ Linear or click the Linear Dimension button on the Dimension toolbar.

AutoCAD prompts you:

Specify first extension line origin or