Gear generator

Gears that actually mesh

Teeth are drawn with the involute profile and a 20° pressure angle, the same as commercial gears. That's why two gears made here with the same module turn together smoothly, and also mesh with bought parts of the same module.

Dimensions come from standard formulas: the pitch diameter is module × teeth, the outside diameter adds two modules, and the center distance of two gears is module × (first gear's teeth + second gear's teeth) ÷ 2.

How to choose

• Ratio: if the small one has 20 teeth and the big one 40, the big one turns half as many times with twice the torque.
• Module: 1 to 2 for 3D printed parts; under 1 prints poorly with a 0.4 mm nozzle.
• Teeth: 12 or more avoids very thin teeth; with fewer, the tooth gets weak.
• Hole: print it a little larger than the shaft (0.2 to 0.3 mm) so it fits.

Making them last

Printed gears work well for mechanisms, toys, models and light repairs. For heavy loads, PETG or nylon, more thickness and a bigger module are better.

Printing tips

• Print them lying flat, as they come in the file, without supports.
• Use 3 or 4 walls and 40% infill or more: teeth work under load.
• Layers of 0.12 to 0.16 mm give smoother teeth that turn better.
• If they turn stiffly, sand a little or raise the "Backlash".

Frequently asked questions