2015 to 1 Harmonic gear reduction

thingiverse

This print demonstrates a diferental harmonic reducer. It is a two stage strain wave gear train that subtracts the reduction of the two stages resulting in a 2015:1 gear reduction. (and 31:1 for v1b) It uses 17x 6mm spheres for the eliptical ball bearing. Airsoft pellets work well as would 6mm glass, nylon, Delrin, or steel balls. Tolerances are tight so print the included "tolerance check" file first. It's a circular ball bearing that prints quickly, uses 19x 6mm spheres, and should spin freely with minimal backlash when your settings are dialed in. For smoothest motion, sand off any raised seams. To assemble the bearing, place the inner race inside the outter race but offset to one side. Insert all 19 ball bearings, then "snap" the inner race onto center. Finally use a narrow flat bladed screw driver to spread the balls out evenly while you snap in the bearing cage. To make the reducer, print these 3 files multip part files. "Diferential Harmonic Reducer Case v1.3mf", "Diferential Harmonic Reducer eliptical BB n spline v1m.3mf", and "Harmonic V1 demo handle.stl" The flex spline has a small notch on the top side, this goes "up" when inserted into the large case half. The small case half is secured by slipping a length of 1.75mm filament through the hole in the side of the case into the slot between the two case halves. Be sure to leave a short tail sticking out if you ever want to take the gear-box apart later. "Diferential Harmonic Reducer Case v1.3mf" is an alternative output case that has a 1:1 reduction on the second harmonic reducer stage. The output is much smoother but only has a 31:1 gear reduction. Finally, I've included full build plate .stl, .3mf and .amf files for the tolerance check and the v1 harmonic reducer to help with part orientation and printing. P.S. I also included the Solidoworks 2020 design files. Combined with gear profiles from http://hessmer.org/gears/InvoluteSpurGearBuilder.html this should help you make customized versions for your own use.