Does anyone have advice about how to model a part with a keyway?  I've tried constraining it a number of ways.  The way that seems most logical to me is a roller/slider fixture on the face in contact with the key.  However when I do this I get an error when solving that says it may be under-restrained.  I'm applying a torque to the shaft itself.  I can get a solution when I use fixed geometry on that same keyway face, but I don't believe this is correct since in reality the face is only constrained in the normal direction.  Any advice?