Originally posted by ctbram PS - I have been working on the piston linkage thing but I ran into a problem with this rig. If I use my aim constraint method to keep the pistons and cyclinders pointed at wach other then I run into wacked out behavior when I try to parent those parts to the joints. So I will have to rethink how to rig these. -Rick M Do you want my project file, so you can see the rig?