3D renderThe Pocket Cycloid · 3D render of the actual model; colours are illustrative.
Pocket Cycloid 10:1
A palm-sized cycloidal gearbox you turn by hand. Ten turns of the knob walk the dial round once. Five printed parts, no hardware.
Not on sale yet. Watch @harryson.stl for the launch, or email help@harbeworks.com.
The design is finished and checked in CAD, but we have not printed it yet. Figures below come from the CAD model and slicer estimates. Desk toy for ages 14 and up; small parts.
A robot-joint gearbox in your palm.
The knob turns an eccentric cam. The cam rolls a 10-lobe disc around a ring of 11 posts, and every turn of the cam walks the disc back by one lobe: a tenth of a turn.
Five pins on the dial ride in the disc's holes, so the dial creeps round the other way at one tenth of the speed. Five windows in the dial let you watch the disc wobble.
It is the same principle as our motor-driven Cycloid Drive 25:1, scaled down to five printed parts.
What we know so far.
From the CAD model and Bambu Studio estimates, October 2026. Not yet printed.
| Spec | Value | Source |
|---|---|---|
| Ratio | 10:1, reversed | CAD motion study: cam 90° turns the dial 9° the other way |
| Size | Ø54 × 21 mm | Assembled, from the CAD |
| Parts | 5 printed, 0 bought | Snap-fit dial, press-fit knob |
| Running clearance | 0.25 mm per side | Disc to posts, at every crank angle checked |
| Filament | About 24 g PETG | Bambu Studio estimate, all five parts |
| Print time | About 2 hours | Bambu Studio estimate, A1 0.4 mm |
| Physically tested | Not yet | We publish fit notes after our first print |
Four steps, no tools.
The file pack includes an illustrated print and assembly guide.
1. Cam onto the pivot · 3D render 
2. Disc over the cam, lobes between the posts · 3D render 
3. Snap the dial in under the lip · 3D render 
4. Press the knob onto the shaft · 3D render
When can I get it?
Soon. The files are finished and checked in CAD; we are printing our first one before we sell it. Follow @harryson.stl to see it turn.
Files or a printed one?
Both are planned: a digital file pack for your own printer, and a printed, assembled one for your desk.
Do I need any hardware?
No. Five printed parts: the dial snaps in and the knob presses on.
Is it a toy for kids?
No. It is a desk toy for ages 14 and up and has small parts.
Want the big one?
The motor-driven Cycloid Drive 25:1 is a free download.
Want one now?
The big motor-driven version is a free download today.