Designed and built a compact cycloidal gearbox to achieve a 30:1 reduction, enabling high torque output from a low-cost motor as an alternative to expensive high-torque actuators. The system was optimized for zero backlash through iterative tolerance tuning and manufacturing adjustments, resulting in precise positional control. The full assembly weighs 445 grams and is intended for integration into compact robotic systems.
The gearbox consists of
14 PETG 3D printed parts
3 different types of bearings
Standoffs used to position and support bearings
Pins and bushing enabling smooth sliding on the disc
Heated inserts for durable fastening
M3 screws for assembly
Nema 17 Motor (0.84 Nm)
DM556 Microstep Driver
Challenges Faced
Some of the main challenges included accurately designing the cycloidal profile and ensuring proper meshing. This was resolved by referencing a paper that outlined how to generate the geometry in SolidWorks using the equation-driven curve tool, allowing for precise and repeatable profile creation. The paper can be found here.
Achieving proper fit was challenging due to 3D printing tolerances, which introduced backlash. Instead of redesigning the system, I identified the issue as dimensional inaccuracy and corrected it by adjusting XY compensation by 0.05 mm, eliminating backlash and improving fit.
Next Steps
I am integrating an AS5600 Magnetic Encoder Module to measure the absolute output angle of the gearbox. Using its I2C interface, I am already able to read precise angular position directly from the output shaft. This enables closed-loop control, eliminating the need to rely on motor step counts, which was unreliable due to the 30:1 reduction requiring ~30 motor rotations for one output rotation.
