Article URL: https://github.com/tom-ilan/cycloidal_gearbox Comments URL: https://news.ycombinator.com/item?id=49140396 Points: 91 # Comments: 19

This is my cycloidal gearbox I built, and the python script I created to generate it! This gearbox was a handcranked gearbox specifically meant to test the validity of the python cycloidal generator. It had a gear ratio of 1:9. This design was a micro cycloidal gearbox with a ratio of 1:9, meant to only take up the same footprint as a NEMA 17. Due to the tight tolerances needed for a small cycloidal drive and the lack of precision offered by 3D printing, this design did not work. This gearbox was the first working version to run on a NEMA 17. It has a larger footprint compared to Version 2 allowing greater tolerances and a fully functional design. This python script was based on the SolidWorks article Building a Cycloidal Drive with SOLIDWORKS. The two main parametric equations I used were: $$x = R \cos(t) - E \cos(N t) - r \cos(t + \psi), \quad y = R \sin(t) - E \sin(N t) - r \sin(t + \psi)$$ $$\psi = \text{atan2}\left(\sin((1 - N) t), \frac{R}{E \cdot N} - \cos((1 - N) t)\right)$$ Reduction ratio: $1 : (N - 1)$ (rotor rotates opposite to input shaft). This section is dedicated to Version 3, whose CAD files can be found under cad_models/version_3. The housing pins can be replaced with MR128 bearings allowing for less friction and higher efficiency in the gearbox.