Planetary Gearbox (NEMA 17)

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Summary Revision of "Planetary Gearbox for Nema 17 Stepper" by lasdasdas, based on initial design "Compact Planetary Gearbox" by raldrich. The gearbox ratio is inverse, increasing rotational speed of stepper by a factor of about 5:1. Gears have been updated to reduce tolerances and increase ratio based on the Getriebe Bibliothek fuer OpenSCAD / Gears Library for OpenSCAD by janssen86. The case now matches NEMA 17 standard dimensions (42mm square, cut corners). The sun gear has a M8x0.75 thread (ISO Fine Pitch III, DIN 13-4) to attach chucks or collars securely. Use glue to secure the sun gear axis, or install a nut to fix it on bearing. I glued the "Gear3-MotRing.stl" under the lower planet holder for added stability. To assemble this gearbox, you will need to print each of the provided *.stl parts and three "Gear3-PlanetGearXS.stl" components. Some parts require turning before printing, such as the upper planet holder. Bill of Materials (non-printable parts): * Planet holders: 3x M3 nuts, 3x M3x14 screws (socket head cap, hex key, DIN 912) * Case fixed on stepper: 4x M3x30 screws (socket head cap, hex key, DIN 912) * Sun gear: 1x Bearing 688ZZ (8x16x5), to hold sun gear axis * Optional: 1x M8x0.75 nut to fix sun gear axis Finishing and Assembly: After printing, some parts may require sanding to achieve a smooth finish. The gearbox works as expected overall, but I have not tested it at maximum torque yet. Depending on slicing and printing settings, tolerances can vary. To address this issue, try adjusting the diameter of the planetary gear. The included gear is about 98% of the original diameter from the gears library to reduce friction and increase smoothness.