4 : 1 · NEMA 17 gearbox

A one-stage 4 : 1 reducer for a NEMA 17 stepper: 5 mm D-flat sun, three planets, 8 mm output.

Stepper gearboxes4 : 13 planetsRing held

Build it with your AI

Using the CheapCADTools connector, design a 4 : 1 planetary gear set in Planetary Gear Designer: module 1 mm, 20° pressure angle, spur teeth, a 21-tooth sun, 21-tooth planets and a 63-tooth ring, three planets, a profile shift of 0.2 on the planets, face width 10 mm. The sun: a 5 mm bore with a D-flat 0.5 mm deep. The carrier's output: an 8 mm bore. Set an input torque of 0.45 N·m. Check the design, apply any Auto-fix it suggests, then export every part (the sun, a planet, the ring and the carrier) as STEP and STL and give me the download link.

Paste it into Claude, ChatGPT or any AI app with the CheapCADTools connector, and it designs this planetary set with you, checks it and hands you the files. How to connect your AI.

What's in this design

Sun

21 teeth · no shift · tip Ø22.99 mm · face 10 mm · bore Ø5 mm D-flat (0.5 mm flat) · no hub

Planets · 3

21 teeth · shift +0.2 · tip Ø23.39 mm · face 10 mm · bore Ø5.3 mm on a Ø5 mm pin · print 3

Ring

63 internal teeth · shift −0.4 · outside Ø76.57 mm · rim 5 mm below the roots

Carrier

straddle (two discs and posts) · disc Ø60.8 × 5 mm · 3 pins Ø5 × 21.0 mm · output bore Ø8 mm

The set · Module 1 · 20° · spur

4 : 1 reduction: the ring is held, the sun is the input and the carrier the output.

Notes

Hardware: 3 × planet pin Ø5 × 21.0 mm; 3 × M3 screw, about 11 mm long.

The link opens the whole set in the Planetary Gear Designer's 3D view. Change the teeth, the number of planets or stages, which member is held, the carrier, bores or hubs, then download STL, STEP or the carrier's DXF and SVG.

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