Generating real involute gears with AI (that actually mesh)

Gears are where casual 3D generation gets exposed. A gear that merely looks like a gear — wavy teeth, eyeballed spacing — will bind or skip the moment it meets another one. Real gears are maths: an involute tooth profile, a module shared by every gear in the train, and centre distances derived from pitch diameters. Here is how to get gears from a text description that actually mesh.

The three numbers that matter

• •Module (mm) — the tooth size. Every meshing gear in a train must share it.
• •Tooth count — sets each gear’s pitch diameter (d = module × teeth) and the ratio.
• •Pressure angle — 20° is the modern default; only change it if you must match an existing gear.

Describe the train, not the gear

The classic failure mode is generating each gear separately and hoping they fit. Tooth phase and centre distance only work out when the whole train is computed together. So describe the system: “Two-stage reduction, module 2, 12-tooth pinion driving a 36-tooth gear, second stage 15 to 45 teeth, 8 mm bores with keyways.”

AiCadGen builds gear trains as a single computed system — spacing and tooth alignment come from the gear maths, not from arranging separate models by eye. The meshed pairs land at their correct centre distances, ready to check ratios and mount points.

Planetary sets

Planetary (epicyclic) trains add two constraints people forget: the ring must satisfy ring = sun + 2 × planet, and the planet count must divide evenly into (sun + ring) for equal spacing. Describe the intent — “planetary set, module 1.5, 12-tooth sun, three planets, about 4:1 ratio” — and let the generator solve the tooth counts that satisfy the geometry.

From model to part

Export STEP if the gears head to CNC or further CAD work, STL or 3MF for printing. For printed gears, a module below about 1.2 mm loses tooth fidelity on an FDM machine — go bigger and adjust the ratio with tooth counts instead.

If you want to see the shape of a working prompt first, the free example gallery includes meshed gear-train and planetary samples you can open and refine.