3 : 1 · 32 DP, hex out

The 3 : 1 stage, a big sun and small planets, 8 mm keyed in, ½" hex out.

FRC & ½" hex3 : 13 planetsRing held

Build it with your AI

Using the CheapCADTools connector, design a 3 : 1 planetary gear set in Planetary Gear Designer: diametral pitch 32, 20° pressure angle, spur teeth, a 42-tooth sun, 21-tooth planets and an 84-tooth ring, three planets, face width 9.5 mm. The sun: an 8 mm bore with a keyway 2 mm wide and 1 mm deep. The carrier's output: a hex bar bore, 12.7 mm across flats (inch sizes), a retaining ring on the top face. 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

42 teeth · no shift · tip Ø34.92 mm · face 9.5 mm · bore Ø8 mm, keyway 2 mm wide × 1 mm deep · no hub

Planets · 3

21 teeth · no shift · tip Ø18.26 mm · face 9.5 mm · bore Ø5.3 mm on a Ø5 mm pin · print 3

Ring

84 internal teeth · no shift · outside Ø76.89 mm · rim 3.97 mm below the roots

Carrier

straddle (two discs and posts) · disc Ø64.09 × 5 mm · 3 pins Ø5 × 20.5 mm · output hex 1/2" (12.7 mm AF) bore, SH-50 / 5100-50 (1/2") retaining ring on the top face

The set · 32 DP · 20° · spur

3 : 1 reduction: the ring is held, the sun is the input and the carrier the output.

Notes

Hardware: 3 × planet pin Ø5 × 20.5 mm; 3 × M3 screw, about 11 mm long; 1 × SH-50 / 5100-50 (1/2") retaining ring.

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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