PhotoPhoto: both, printed in PLA · real photo of our two printed units.
Pocket Gearbox Duo
Both pocket gearboxes in one set, coming soon. Turn both knobs at the same speed: one dial goes round after 4 turns, the other needs 10 and goes backwards.
Not on sale yet. Watch @harryson.stl for the launch, or email help@harbeworks.com.
Both are printed: our first Pocket Cycloid and first Pocket Planetary are printed in PLA and working (one print of each so far; fit details not measured yet). The set itself is not on sale yet. Desk toys for ages 14 and up; small parts.
Two ways to slow a spin down.
Pocket Cycloid: turn the knob 10 times and the dial goes round once, the other way. Inside, a wobbling disc rolls around a ring of posts and creeps one notch for every turn of the knob.
Pocket Planetary: turn the knob 4 times and the dial goes round once, the same way. Three small gears roll around a middle gear like planets around a sun, and they carry the dial with them.
Try this: turn both knobs at the same speed and watch which dial wins. Slower means stronger: the same trick lets a small motor lift a robot arm.
Curious how the wobbling-disc kind works? Try the interactive cycloidal drive.
What we know so far.
From each model's CAD and Bambu Studio estimates, October 2026.
| Spec | Value | Source |
|---|---|---|
| Pocket Cycloid | 10:1, reversed · Ø54 × 21 mm | 5 printed parts; first unit printed in PLA and working |
| Pocket Planetary | 4:1, same way · Ø57 × 21 mm | 7 printed pieces; first unit printed in PLA and working |
| Hardware | None | Both snap together; the knobs press on |
| Filament | About 50 g of PLA for both | Bambu Studio estimate, one plate each |
| Print time | About 2 h 15 min for both | Bambu Studio estimate, A1 0.4 mm, one plate each |
| In one box | Stacked, with a card between | Two units stack to 42 mm in a 4 × 4 × 2 in box |
The two gearboxes.
Each one also has its own page with every spec and the assembly steps.
Pocket Cycloid 10:1: 10 knob turns, one dial turn, the other way. First unit printed in PLA and working; print files available now. See it
Pocket Planetary 4:1: 4 knob turns, one dial turn, the same way. First unit printed in PLA and working; print files available now. See it
Can I get it now?
Not as a set yet. Both gearboxes are printed and working, and each one's print files are available now on its own page. Follow @harryson.stl for the set.
What will be in it?
Planned: one file pack with both complete sets of print files, or both printed, assembled units in one box with a card that explains how each one works.
Do I need any hardware?
No. Both snap together and the knobs press on.
Is it a toy for kids?
No. They are desk toys for ages 14 and up and have small parts.
Want the big one now?
The motor-driven Cycloid Drive 25:1: free parts list, print files today.