I recently spent several months designing and prototyping a low-backlash angular gear drive. The goal was to create a compact transmission for robotic wrists that avoids bevel gears and belts — while still transmitting torque smoothly at various angles.

The design was inspired by roller pinion linear systems, but adapted for angular motion. Paper: https://www.mdpi.com/2076-3417/12/11/5620

To be honest, I couldn’t figure out the tooth profile for the straight pinion variant, so I brute-forced it — by writing a script that rotates two bodies at a set gear ratio and performs boolean cuts between them.

I 3D-printed several prototypes, including a working wrist differential with embedded reducers and a double hollow shaft drive.

Here's a video about it: https://youtu.be/VXcuryyRGbo

Would love to get feedback — especially from those working in robotics or mechanical design.