Compact Strain Wave Gear Actuator(s)

A compact modular design of the strain wave gear for general robotic applications.

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Strain wave gear (a.k.a Harmonic Drive) have been widely regarded as one of the most efficient and accurate transmission gear designs. These gear sets are expensive and hard to be manufactured. I have therefore implemented a self-design 3D printable Strain Wave Gear actuator. Unlike other 3D printable gearbox design, this design features a complete gearbox actuator, meaning that this is a direct drop in for robotics applications. The available ratios are 1:31, 1:21 and 1:15. The result is an actuator that is robust and back-lash free.

Final set test (1:15, 1:21 and 1:31 ratio).


  • Strain wave gear, ratio 1:31, 1:21 and 1:15
  • Weight (no motor): 1241.1 g (1:31)
  • Overall diameter: 145 mm
  • Cooling: passive
  • Backlash: < 5 arcmin


.step file for intergration.

stp - 18.28 MB - 05/20/2019 at 17:09



Printing with a printer that has X/Y resolution of 100 micron, ideally in nylon or a flexible filament (but not too soft).

Standard Tesselated Geometry - 1.53 MB - 05/15/2019 at 18:09



Printing with a printer that has X/Y resolution of 100 micron, ideally in nylon.

Standard Tesselated Geometry - 1.14 MB - 05/15/2019 at 18:08



Printing with high infill (>= 80%).

Standard Tesselated Geometry - 274.69 kB - 05/15/2019 at 18:08


Standard Tesselated Geometry - 298.91 kB - 05/15/2019 at 18:08


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View all 6 components

View all 3 project logs

  • 1
    Assembly timelapse video

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Sergey Omelchenko wrote 2 days ago point

Have you measured max torque? Very curious on that

  Are you sure? yes | no

Leo Vu wrote 2 days ago point

No I have not. But I will definitely do that because I am using this gearbox for my 6 axis robot. I am waiting for the motor to come.

  Are you sure? yes | no

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