Sketches, gears and the arithmetic behind them

A small notebook about parametric 3D modelling and ordinary machine parts — spur gears, flanges, nuts and shafts. Drawings, formulas and the habits that keep a model from falling apart after the third edit.

Notes

• 2026-11-02
  Parametric habits that survive the third revision

  Naming parameters, sketching from the origin, and why fillets go last.

• 2026-10-12
  Flange bolt circles: a short checklist

  Pitch circle, hole count, clearance holes and the one angle people forget to rotate.

• 2026-09-21
  Involute spur gears without the guesswork

  Module, pressure angle and the four circles you actually need to model a gear.

Recent drawings

Schematic sketches of parts I modelled recently. More on the portfolio page.