OpenSCAD Hypocycloid gearbox generator

thingiverse

UPDATE: Have configured scad file (v1.31) to generate housing, etc, for NEMA 17 motor. I have actually tested this now, and it works, although it's a little uneven on motion transfer (possibly due to print inconsistency). The gearbox had to be 'run in' with a bit of autosol (chrome polish paste) before it worked properly, then the autosol cleaned out. I've actually printed this in PLA and ABS (and treated the ABS one with acetone vapour). I don't think there's much to chose between the plastics, although the PLA one seemed to work better in the end. NOTE1: With ABS, shrinkage becomes a major issue, peeling the corners of the housing from the print bed on my Replicator 2 clone. NOTE2: The parameters have only been tested for a NEMA17 motor so far, so don't expect it to work without a hitch for different parameters! This is still a work in progress for a project I'm working on at the university. Instructions The complete model provided requires (as well as the printed parts): an M6 threaded shaft of about 60 or 70 mm diameter. Several M6 nuts to join the output annulus to the shaft, and also to join two 6mm ID bearings (19 mm OD). two 10 mm ID, 15 mm OD bearings to fit the cam in the sun assembly. four self tapping screws (not sure what size, but quite small for screwing the sun assembly together) four M3, 30 mm cap screws to attach the gearbox to the motor. at least four 10 mm M3 screws and nuts to hold the top part of the housing together. As yet unprinted. I've found with my printer, there is typically about half a nozzle diameter extra material, thus a 10 mm diameter cylinder will come out at 10.4 mm on my printer with a 0.4 mm nozzle. To alleviate this issue, there is a 'Clearence' variable (in scad file) which can be set to half the nozzle diameter (or bigger) to compensate. Gear ratio achieved is 1:(pegs^2 - 1). I think 1:625 should be achieveable in about a 70 mm diameter gearbox of, say, 15 to 20 mm height... In the process of designing a housing so it can be tested.