30:1 reduction cycloidal drive for nema 17 stepper

Description

I couldn't find a free reduction gearbox design for a Nema 17 stepper - so I made one myself!

My design only requires 2 608 skateboard bearings and a bunch of m3 screws.

The drive works with the cycloidal reduction principle where two out of phase disks slide on a rotor and generate torque.

Unlike planetary gearboxes it features a way bigger reduction ratio compared to its size, is more resistant to backdriving, has near zero backlash, a way higher impact resistance and is easier to print. all of these benefits make it the perfect pick for robotic arms. the only issue is that cycloidal drives are, in general, less efficient than planetary gearboxes.

it achieved a peak torque of 10.5 Nm with only PETG parts and a 59Ncm Nema 17 stepper.

I also attached a pdf assembly manual, but i think the assembly should by quite self explanatory.

Required parts:

• 608 skateboard bearings, 2x

• m3*4 to m3*6 screws 4x

• m3*10 screws or longer, 4x

• m3*20 to m3*30 screws, the longer the better (max 33mm), 4x

• some kind of mechanical grease, I used Superlube

• (optional): m3 heat inserts for the back and front mounting points (they give stronger screw connections), 10x

• a Nema 17 stepper

  • more about its specs in the manual
    

Also, feel free to message me if i made any mistakes or you have any questions!