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NEMA 17 50:1 Strain-Wave Reducer Kit
Three-piece print-in-one-go strain-wave (harmonic) reducer for a NEMA 17 stepper: an 85 mm housing with the 31 mm M3 bolt square and 22 mm pilot recess that carries a 102-tooth internal ring, a thin-wall 100-tooth flexspline cup with a 20 mm square M3 output pattern, and an elliptical wave generator that grips the 5 mm motor shaft with an M3 set screw. Module 0.75 teeth give 50:1 in a 30 mm tall stack; the pieces print side by side joined by snap-off sprues.
NEMA 17 Snap-Off Planetary Reducer Kit
A 4:1 planetary gearbox for a NEMA 17 stepper printed as one snap-off kit: a 78 mm ring housing with 45 internal module-1.5 teeth, a 15-tooth sun (5.3 mm bore, M3 grub screw hole), three 15-tooth planets riding on 5 mm carrier pins, a 60 mm output carrier with four M3 heat-set holes on a 30 mm circle, and a cover held by four M3 self-tap screws. The housing bolts straight to the motor's 31 mm square pattern with the heads recessed in the floor and a 22.4 mm pilot recess underneath, so an arm or drum bolted to the carrier gets four times the motor torque at a quarter of the speed.
NEMA 17 Roller Traction Ring Housing
A gearless roller-traction reducer housing that bolts to a NEMA 17 face (31 mm M3 pattern, 22 mm pilot recess). Three 608 bearings (22 mm OD) work as planet rollers, squeezed between the bare 5 mm motor shaft and a 48.8 mm ring bore. The ideal fit would be 5 + 2×22 = 49 mm, so the 0.2 mm undersize adds preload and the drive has no backlash and no teeth to strip. With the output taken from the carrier, the ratio is 10.8:1. The part is 64 × 64 × 18 mm and has four M3 heat-set bosses for the carrier cover.
Cycloid Retainer Cover Ring
The Ø96 x 6 mm lid ring for the 'NEMA17 Cycloidal Joint Actuator' kit. Its flat underside traps the Ø60 output flange and caps the sixteen 5 x 18 mm steel ring pins. The Ø50.6 bore (chamfered 0.6 mm on top) runs as a plain bearing around the Ø50 output boss. Four M3x30 SHCS pass through Ø3.4 holes on the R42 stack circle and clamp the stack together.
Six-Pin Output Carrier
This is the rotating output flange of the 'NEMA17 Cycloidal Joint Actuator' kit. It has a Ø60 x 6 mm flange that sits under the cover lip and a Ø50 x 9.5 mm boss (15.5 mm tall overall). On the underside it takes a 625 bearing (5 x 16 x 5) in a Ø16.05 x 5.2 pocket and six 5 x 14 mm steel output pins pressed into Ø5.0 x 5.5 blind holes on a 21 mm radius. The top face has four M3 brass heat-set inserts (Ø4.0 x 6) on a Ø36 circle for bolting on the output arm or your own payload.
15-Lobe Cycloidal Disc
The 15-lobe reduction disc (about Ø66 x 9 mm) for the 'NEMA17 Cycloidal Joint Actuator' kit. It rolls against sixteen 5 mm steel ring pins on a 34 mm pitch radius with 1.5 mm eccentricity, giving a 15:1 reduction. Its Ø24.6 chamfered centre bore runs greased on the Ø24 eccentric cam. Six Ø8.4 through-holes on a 21 mm radius drive the six 5 x 14 mm steel output pins of the carrier.
Cycloidal Motor Base Plate
The 96 x 96 x 8 mm foundation plate of the 'NEMA17 Cycloidal Joint Actuator' kit. It bolts to a NEMA 17 stepper with 4 M3x8 screws on the 31 mm square, sunk in Ø6.5 counterbores, and has a Ø22.4 pilot recess and a Ø16 shaft hole. It takes 4 M3 brass heat-set inserts on the R42 stack circle to clamp the ring housing and cover, and has 4 Ø5.5 M5 holes at ±40 mm for mounting to 2020 extrusion. The top face stays flat inside Ø96 so the rolling 5 mm ring pins have a smooth surface to run on.
NEMA 17 Cycloidal Reducer Cartridge
A 16:1 single-disc cycloidal gearbox that bolts directly to a NEMA 17 face (31 mm square M3 pattern, 22 mm pilot boss recessed, 5 mm shaft), giving a hobby robot joint high reduction and low backlash in a 66 mm dia x 22.5 mm stack instead of a €1000 harmonic drive. It prints as four nested pieces in one job — pin housing, cycloidal disc with six 6 mm output pins, eccentric cam with an M3 grub screw, and an output carrier with three M4 mounting holes on a 38 mm circle.
NEMA 17 Belt Reduction Bearing Plate
A 106 x 52 mm mounting plate that turns a NEMA 17 into a 3:1 belt reduction: the motor bolts to the top on the verified 31 mm square pattern with its shaft dropping through a 23 mm pilot clearance, and an 8 mm output shaft runs in two press-fit 608 bearings in a 34 mm tower at 58.5 mm centres — the right spacing for 20T to 60T GT2 pulleys on a 200 mm closed-loop belt. Gussets take the belt pull in the XY plane, and four M4 holes on a 92.5 x 37 mm rectangle bolt it to a chassis deck on 20 mm standoffs so the belt runs underneath.