11-to-1 NEMA17 hypocycloid reducer

Inspired by chriswal's Nema 17 Cycloidal Gear box prototype and Otvinta's tutorial I decided to give it a go and see if I could design and print a working hypocycloid reducer for Nema17 stepper with 11:1 ratio. I just basically scaled the model in the Otvinta's tutorial to fit the frame of Nema17. The eccentric input 'shaft' is almost a copy from the chriswal's design. Nonetheless I have modeled all the parts in Blender and Fusion360 myself.

After the first print in PLA and assembly I was amazed to see that it really works and basically has no play/backlash whatsoever. I used PTFE grease to lubricate the gear and output. To share similar feeling of success, you need to have your printer very well tuned to produce dimensionally accurate prints.

You need:

• 2x 608 bearings,
• M3 nut and M3x5mm set screw for locking the input to stepper shaft.
• M5 hexagonal head bolt for output.

How I Designed This

Creating or importing mathematically defined curves in Fusion 360 is a bit clumsy, I decided to use Blender like in Otvinta's tutorial to create the profile of the CycloidGear. Then I exported the gear as STL from Blender and imported it to Fusion 360 as a mesh. After that I created a mesh section and fit curves to the section. The rest of the design is typical Fusion 360 stuff.