Has anyone completed this build that can give me some insight? This one axis does not make sense to me how it is designed. Module #4 the twisting axis (forearm) has a nylon locking nut sitting on top of a bearing. This does not make sense. I feel the nut should clamp the piece so it rotates with the shaft. What purpose does the bearing do sitting under the locking nut? How can it transfer motion/torque?