<robrotics/>

<actuators/>

Compact harmonic drive actuators you can print at home. Every one ships with its CAD files, a complete bill of materials, and the actual load-cell data behind the torque numbers, because a spec you can't check isn't a spec. All free under CC BY-SA 4.0.

The assembled HDP30: a thin white printed gearbox with a knurled output ring, bolted to the face of a black NEMA 17 stepper.

HDP30

30:1 pancake harmonic drive ยท NEMA 17

Half again the reduction of the HD20, in a thinner stack, off the same motor face and the same $4 of hardware. Torque testing is still pending, and we say so on the page.

  • 30:1 reduction
  • not yet tested
  • ~$3.96 hardware
view the build →

more coming

bigger, smaller, and higher ratio

We're working on other sizes in the same family. Want to be told when they land, or have a size you'd actually use? Say hello on YouTube or email us.

Looking for the HD20? It's in the archive, files and test data intact.

<archive/>

Superseded revisions don't get deleted. Their CAD stays downloadable, their bills of materials still load and their test data stays up, because a dead link is a worse outcome than an out-of-date page.

The HD20 lives there now, and it's worth knowing that it's still the only drive we've put on a load cell. If you need a torque figure you can defend, build that one.

browse the archive →

<design-your-own/>

Every one of these starts in our free harmonic maker, a parametric tooth profile generator that exports DXF. If you'd rather understand the mechanism before you build one, start with harmonic drives, plainly.