⏱️ Chronograph Watch: Gear Train Ratios, Beat Rate and Stopwatch Reading Error (2D dial)

A chronograph dial with a stepping seconds hand and a 30-minute counter, next to the three gears that step the escapement down to one turn a minute. Choose the beat rate and tooth counts, see whether the train matches the balance, the rate error in seconds per day, and the reading uncertainty set by the beat and by the operator. Five numerical checks.