Summary

First test (printed and "working") of my hypocycloid gearbox generator (scad file at http://www.thingiverse.com/thing:481167). Pics will follow when I get my camera back!

This version needs improvements to avoid jerky output motion. Perhaps changing parameters in scad file (peg diameter, etc). Still interesting test that proved it worked!

Note - the linked-to scad file isn't exactly neat and tidy! Sorry!! (still learning)

Instructions

requires:
2x 10 mm ID / 15 mm OD bearings. 4 mm high
2x 6 mm ID / 19 mm OD bearings. 6 mm high.
1x ~70 mm M6 threaded shaft.
4x 30 mm M3 cap screws.
4 (to 6)x 10-15 mm M3 cap screws and nuts.
6x M6 nuts
4x self tapping screws. <=10 mm long, ~2.5 mm dia.

Construction:
Print "Complete.stl" (PLA, no raft or support, 0.4 mm nozzle / 0.2 mm layers, 12-20% infill, 2-3 shells (skienforge47)).
OR: Print from individual files as you wish to experiment. If using ABS, you will need to add 'tabs' to the corners of the larger parts to avoid warping.

Output shaft assembly:
Attach the output annulus (OutputAnnulus.stl) to the output shaft with 2 M6 nuts (one above, one below). Use threadlocker if you want it permanent! Then capture the two 6 mm bearings between 4 more nuts (nut, bearing, nut, nut, bearing, nut), and line up bearings to fit slots in the upper housing (UpperHousing.stl) before tightening bearings in place. Now, screw together the two upper housings with the shaft in place using the 10-15 mm M3 screws and nuts.

Sun assembly:
Insert a 10 / 15 mm bearing into the lower sun section (SunBottom.stl). Insert the cam on top of this (cam.stl), place another 10 / 15 mm bearing on the top of the cam, and push the upper sun section into place (SunTop.stl). Screw together (or glue if you wish) with four self-tapping screws (10 mm long max, ~2.5 mm thread).

Place the motor mount (MotorPlate.stl) onto the motor, and push the sun assembly onto the motor SCREW SIDE DOWN (I got top / bottom mixed up in the code!). Then place the central housing (LowerHousing.stl) on top of the motor mount. Finally, add the output shaft assembly, and screw in place with 30 mm M3 screws.

Once constructed, I found this gearbox a little sticky until I wore it in a bit with the help of some chrome polish paste mixed with grease. I cleaned out the polish after I decided it was probably as smooth as it was getting.

NEMA 17 1:48 hypocycloid test