Size
You can assign Size constraints to lines and all circular elements. At solve time, these elements will be adjusted to the size specified by the constraint. For circular elements, the adjustment is made to the radius; for lines, the length is adjusted. If the adjustment cannot be achieved, Solve fails.
To assign a size constraint:
1. Click Parametric and then, in the Create group, click 
Constraints.
Constraints.The Generate Constraints dialog box opens.
2. In the Action area, click Assign.
3. In the Type box, select Size.
4. Click the element to be constrained.
5. Choose the size for the constraint by any of the following methods:
◦ Click 
OK or select another element. The element will be held at its current size at solve time. This is the default.
OK or select another element. The element will be held at its current size at solve time. This is the default.◦ Type a specific size (radius for circular elements, length for lines) in the user input line and press ENTER.
◦ Type a parameter name or Creo Elements/Direct Drafting expression that defines the size (string input) in the user input line and press ENTER.
Each size-constrained element pair is labeled with the size icon, . If the constraint is set to a specific value or parameter name, that information is appended to the icon.