Spur gear generator

Generate involute spur gears for laser cutting: module, tooth count, pressure angle and bore in; one or two meshing gears out as SVG, with the centre distance and ratio.

Set the module (tooth size), the tooth count, the pressure angle and the bore, and download a true involute spur gear ready to cut. Add a second tooth count to get the mating gear in the same file, with the axle centre distance and the ratio.

Sizing a gear

Pitch diameter = module × teeth; outside diameter = pitch + 2 × module; the root sits 1.25 × module below the pitch circle. Fewer than about 17 teeth at 20° undercut slightly, which is fine for plywood toys and clocks; for a gear that carries load keep both gears at 17 teeth or more and the ratio under 6 : 1 per stage.

Laser-cut gears that run

• Plywood and MDF: module 2 or more, 3–6 mm thick; sand the edges lightly and wax them.
• Acrylic: module 1.5 or more; keep the kerf small and the fit loose, acrylic does not forgive a tight mesh.
• Bores: cut 0.1–0.2 mm under the shaft and ream, or over by the same for a free spin on a fixed axle.
• Stack two layers glued face to face for a wider tooth that wears slower.

Related tools

• Box generator: Closed box, open tray, lift-off lid or divided tray with finger joints, as one SVG.
• Living hinge generator: Six slit patterns, straight to honeycomb, that let a flat sheet bend, sized to your panel.
• Kerf test gauge: Slot gauge and reference square to measure the kerf of your laser on any material.