Free 3D gear generator: spur, helical and herringbone STL

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What this tool does

Teeth with a true involute profile: two gears of the same module mesh, whatever their tooth counts.

Three types: spur, helical and herringbone, with the helix angle you choose.

A pair already in mesh: the second gear comes out at the right shaft distance and turned so the teeth fit.

Module from 0.5 to 6 mm, 8 to 150 teeth, a 14.5°, 20° or 25° pressure angle and a shaft hole.

Adjustable backlash, so the printed pair turns without binding.

Shows the pitch diameter, the outer diameter, the shaft distance and the ratio. All in your browser.

How it works

Define the gear

Module, number of teeth, width and shaft hole. The sizes update as you adjust.

Choose the tooth type

Spur, helical or herringbone, and if you like, add the gear that meshes with it.

Download and print

Get the STL and print it flat, with the shaft vertical. For working parts, PETG or nylon last longer than PLA.

Frequently asked questions

How do I design a gear for 3D printing?

With ilove3d's gear generator three numbers are enough: the module, which is the size of the tooth; the number of teeth; and the shaft diameter. The tool draws the involute profile, the one real gears use to roll without knocking, and gives you the STL. For printers with a 0.4 mm nozzle, a module of 1.5 or more gives teeth that come out well defined.

What is the module of a gear?

The pitch diameter divided by the number of teeth, in millimeters, and it sets the size of each tooth. A module 2 gear with 20 teeth has a 40 mm pitch diameter and a 44 mm outer diameter. Two gears only mesh if they share the module and the pressure angle; the tooth count of each sets the gear ratio.

Which type of gear is best to print?

The herringbone is the favorite for 3D printing: it runs smoother and quieter than a spur gear, centers itself and does not push the shaft sideways as a plain helical does. It prints flat without supports. Spur gears are the simplest if you need to take the gear off by sliding it along the shaft.

How much backlash should I leave?

Between 0.1 and 0.2 mm for most printers. With none, printed gears bind because plastic always comes out a little wider than drawn. If your printer tends to over-extrude, raise it; the tolerance test of the calibration test generator gives you the exact number for your machine.

Question of the month

Which printer do you use?