About this tool
Gears transmit rotation at a fixed ratio. Almost all spur gears have involute flanks: this shape makes the teeth roll on each other instead of sliding, and keeps the ratio constant even if the centre distance is slightly off. The tooth size is given by the module; the pitch diameter is module times number of teeth.
The generator draws the outline with true involutes, tip and root circle per the standard tooth form (addendum 1 × module, dedendum 1.25 × module) and optionally with backlash and a bore. With a mating gear you also get centre distance and ratio. Download the file as SVG or DXF for laser cutting, milling or as a sketch for 3D printing.
How it works
- Enter module and number of teeth, optionally pressure angle, backlash and bore.
- If needed, enter the teeth of the mating gear and read off centre distance and ratio.
- Check the preview in mesh or side by side.
- Download SVG or DXF and cut or mill the gears.
Frequently asked questions
Which module should I use?
Laser-cut gears from 3 to 6 mm plywood work well with module 2 to 4; smaller teeth easily burn or break. For 3D-printed gears module 1 to 2 is common. Two gears only mesh when module and pressure angle are the same.
How is the centre distance calculated?
It is the sum of both pitch radii: module × (teeth 1 + teeth 2) ÷ 2. With module 2 and 20 and 31 teeth that is 51 mm.
Why is there a warning with few teeth?
Below about 17 teeth (at 20°) a cutting tool would undercut the tooth root. The outline here has no undercut, so the tip of the mating gear may touch the root. More teeth or a bit more backlash help.
Do I need to account for the kerf?
Yes, the laser removes some material all around the outline and the teeth get thinner. Measure the kerf with the Kerf Calculator and enter it as an offset in your laser software, or reduce the backlash accordingly. Build a matching box for a gearbox with the Laser Box Generator.