To Measure Diameter
1. Click Analysis > Measure > Diameter, or right-click the graphics window and choose Diameter from the shortcut menu. The Measure dialog box opens.
2. Select a surface, curve, or edge to measure. The diameter value is shown in the measurement panel and in the Measure dialog box.
3. To measure the diameter at a specific location on the surface, click the Point collector, and then select a specific location.