Thanks. It be nice if there was some snapping of the rotation too.  I can rotate the axis so they align with an edge by eye, but it takes some effort and might not be 100% reliable. For example, I might have a trapezoidal solid. I can snap the axis to a corner point of the solid, but then I want the x axis to be pointing exactly along a non-right angle side edge of the trapezoid. So rotating the y and z by eye works, but it be nice if it "snapped" when it got close. Its critical that the axis aligns with the edge to make the realtime animation playback accurate.