manual (with the pointer) rotating of a revolute joint component causes component to relocate, not rotate

[wadeJ4J2S]

I am struggling to animate a joint manually (i.e., grabbing the component with the cursor, and exercising the joint movement).  In the file attached, the LegAndFlange component is joined as a revolute joint to the Hub component, but when I grab the LegAndFlange component to exercise the revolute joint motion, the LegAndFlange component simply moves away (without rotating) from the other components.  What am I doing wrong?  Do I need to "ground" the Hub?

[jeff_strater · Accepted solution]

yes.  Either ground the hub, or join it to another component that, itself, is grounded.  You need something grounded in your design for component drag to work.