[Maciej Nowak] demonstrates just how to produce your own gears with a homemade cutting tool. The cutting tool for the job is an M16 machine tap, chosen for the smaller flutes compared to a hand tap.

Sir William Thomson (better known as Lord Kelvin) designed one such “tide-predicting machine”, an impressive arrangement of gears and pulleys, back in the late 19th century. [Pepijn de Vos ...