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Planetary Gearbox Generator (OwlCAD)

A printable planetary gearbox from tooth counts, with a live check that the planets will fit

Planetary Gearbox Generator (OwlCAD) is a free browser tool for printing a gear reduction without working out the tooth counts by hand. The customizers and the editor are free; only OwlCAD's AI features need the Pro subscription. Exports STL and 3MF; no account needed. Last checked 15 October 2026.

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Opens owlcad.com

At a glance

Price: The customizers and the editor are free; only OwlCAD's AI features need the Pro subscription
Runs on: Browser
Exports: STL, 3MF
Multicolor: No, single color
Account: Not needed
Open source: No
Skill level: Easy: a few settings to tune
Best for: Printing a gear reduction without working out the tooth counts by hand
Selling prints: Allowed OwlCAD's terms include commercial use on every plan, the free tier included: you may sell prints, sell or license the files and use them in a product, with no royalty and no attribution required.
How we checked: Opened the generator Customizer opened in a browser with no account: the default 12/12-tooth, 3-planet set rendered in 3D with all settings, ring teeth 36; pricing and terms read
Checked by: Mike Janssen
Last checked: 15 October 2026

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Sources: Planetary gearbox customizer, OwlCAD pricing, OwlCAD terms (checked 15 October 2026)

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About this generator

The Planetary Gearbox Generator is one of the free customizers in OwlCAD, a browser-based parametric CAD tool. You set the number of teeth on the sun and the planets and how many planets you want, and it works out the ring's tooth count and the reduction ratio. It also tells you live whether the planets will assemble at equal spacing, before you print anything.

You can change the module, the pressure angle (10 to 30 degrees), the thickness, the bore diameter, the backlash (0 to 1 mm) and the ring rim, and keep the teeth apart for printing. The download is an STL or 3MF with the sun, planets and ring as separate bodies.

It runs in the browser with no account and costs nothing; only OwlCAD's AI features are paid. OwlCAD has more than 30 other customizers on the same footing, from gear trains and worm drives to enclosures, hinges and threaded jars, and you can open the result in the full editor if you want to change more. Its terms give you full commercial rights to what you make, the free plan included.