Learning Objectives

After completing this lesson, you will be able to:

1. Add Diameter, Radius and Angular dimensions to a drawing

2. Draw and control Center Marks

3. Flip the direction of an arrowhead

4. Understand the need for Sub-styles

5. Create a sub-style

Dimensioning Diameters

The DIAMETER dimensioning command should be used when dimensioning circles and arcs of more than 180 degrees. AutoCAD measures the selected circle or arc and displays the dimension text with the diameter symbol ( ) in front of it.

1. Select the Diameter command using one of the following:

   • Ribbon = Annotate tab / Dimension panel /

   • Keyboard = Dimdiameter

2. Select arc or circle: select the arc or circle (P1) do not use object snap.

   Dimension text = the diameter will be displayed here.

3. Specify dimension line location or [Mtext/Text/Angle]: place dimension text location (P2)

   

Center marks are automatically drawn as you use the diameter dimensioning command. If the circle already has a center mark or you do not want a center mark, set the center mark setting to NONE (Dimension Style / Symbols and Arrows tab) before using Diameter dimensioning. (Refer to 18-7)

Controlling the Diameter Dimension Appearance.

If you would like your Diameter dimensions to appear as shown in the two examples below, you must change some setting in the Dimension Style Fit tab.

Dimensioning Radii

The Radius dimensioning command should be used when dimensioning arcs of less than 180 degrees. AutoCAD measures the selected arc and displays the dimension text...