Add radial measurements

To measure the radius of a curve or arc

1. Click the Radius icon, or choose Measure > Radius from the Locators palette menu.
2. Click the curve you want to measure. You can move the new measurement while the mouse button is down. When you release the mouse button, the measurement is attached to the curve.
3. The new locator appears.

   A point (cross) indicates the center of the radius (that is, the center of a circle having the same radius as the curve at the position of the locator).

   • Drag the arrow head to move the measurement along the curve.
   • Drag the text or leader line to change the length of the leader.
   • Hold and click off the measurement with the to toggle display of the center of the circle/center of curvature.

To measure the diameter of a circle

1. Click the Diameter icon, or choose Measure > Diameter from the Locators palette menu.
2. Click the circle you want to measure. You can move the new measurement while the mouse button is down. When you release the mouse button, the measurement is attached to the circle.
3. The new locator appears.
   • Drag the arrow head to move the measurement along the curve.
   • Click the to align the measurement horizontally. Click the to align the measurement vertically.
   • Click and drag the text or dimension line to change the length of the leader.
   • Hold and click off the measurement with the to toggle to a different display that shows the center of the circle.

To edit a radial locator

1. Choose Windows > Information > Information window to open the Information window.
2. Click the Move locator icon, or choose Move locator from the Locator palette menu.
3. Click the locator you want to edit.
   • Drag the arrow head to move the measurement along the curve.
   • Drag the text or leader line to change the length of the leader.
   • Hold and click off the measurement with the middle mouse button to toggle display of the center of the circle (or center of curvature).
   • Use the options in the Information Window to edit the object.

Tips and notes

• The measurements automatically update when you move or modify the objects/locators the measurements are attached to.
• You cannot add a radius measure to a straight line.
• You can add more than one radius locator to a curve or arc.
• When the “center of curvature” of a measurement is displayed (-click off the measurement with the ), you can snap to the centerpoint using Magnet snapping.
• Using the Radius or Diameter tools on a non-rational circle will show that the circle is not perfectly round. For perfectly round circles, you must use rational geometry.
• You can get a continuous comb of radius values along a curve using the Plot Value > Radius option of the Curve curvature tool.