universal joint thingy emulating two rolling spheres

thingiverse

I watched a fascinating video where a clever robot wrist mechanism was demonstrated. I designed the fundamental mechanism in Fusion 360, then 3D printed the parts in PLA plastic using 1.75 mm filament rivets for the joint shafts. To prevent the filament from sticking, I flattened them with a soldering iron at approximately 150°C and covered them in kapton tape. This model requires: * 2 bases * 6 joints * 3 rods (which need support) The mechanism operates similarly to two spheres rolling against each other, except for axial rotation, effectively functioning as a universal joint. I plan to incorporate this wrist mechanism into a robot arm in the future. In the CAD model, I'm limited to rotating the joints by only a few degrees, and I'm unsure if this is due to Fusion's kinematic solver or an error on my part.