Parameters can be defined in SpaceClaim, even if the geometry was created in DesignModeler or another CAD software, as is the case for us. To do this, right-click on from the Project Schematic window and choose "Edit Geometry in SpaceClaim..." as shown below:
Once SpaceClaim has opened, go into the Design tab and choose the Pull tool. Select the arc that represents the hole and then choose the Ruler option from the mini toolbar that appears:
Now move the cursor until it snaps to the center of the arc:
Now, click the box with the "P" to the right of the dimension. You can also go into the Groups tab and choose "Create Parameter" near the top of that window. This will create a parameter named Group1 under a folder called Driving Dimensions. Call the parameter "DS_R." You can always go back and rename your parameters by right-clicking on them and choosing "Rename" in the context menu that appears. If you click on your parameter, you can see the current dimension being used in the model. Make sure your Groups tab looks like the image below before continuing:
SpaceClaim can now be closed.