3D Printed Harmonic Drive: Two Disks Enable a Compact Gearbox

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March 28, 2026 News 9048

Traditional reduction gearboxes require numerous components and have a bulky structure. Maker Raph, drawing inspiration from electric bicycle drive systems, has designed a 3D model of a harmonic pin-ring drive consisting of just two disks.

Compared to conventional cycloidal gears which still require multiple components (including pins to compensate for the uneven motion of an eccentric drive), this design significantly streamlines the structure by using two toothed disks offset by 180 degrees that compensate for each other's wobbling motion. As a demonstration model, it is particularly well-suited for 3D printing—users can not only view it digitally but also print a physical object to intuitively understand the complex movement mechanism.

Raph has open-sourced the files on GitHub and MakerWorld for those interested to download and test. This approach of simplifying complexity offers new possibilities for compact gear design.