Hey, I downloaded your first file just after you posted it, but it had like 6-7 armatures in it, one of them a humanoid and the mesh to go with it, and I did re-read your post header (I can’t see your video), so I trashed it (your file). Any how, I see what you are after now, your solution is good, but it can’t be transformed - it’s static in the scene, which is not a problem if it suits your need. When building this type of rig, it’s critical that the bone lengths (diagonal bones) are the same length. As far as your jerking movement goes, could be that you are using ‘Quaternion Rotations’, at least changing it to ‘XYZ’ fixed it for me. Do Not use quat rotation mode for stuff like this - at least in this case, mechanical rigs generally don’t require it. I’m posting a screen shot of the rig set-up I use for something like this, every thing is visible that is relevant.