Learn how a mechanical watch works — on a living movement
An original educational movement, watchbase Cal.1, built on the classic 16.5-ligne hand-wound architecture. Power from the mainspring travels through a train of gears, is metered into a steady rhythm by the escapement, and finally becomes the motion of the hands. The chapters that follow trace that path from power inlet to time outlet.
The only power source is the mainspring coiled inside the barrel. Turning the crown drives the stem, winding pinion, crown wheel and ratchet wheel in turn, coiling the spring around the barrel arbor. The click drops into the ratchet teeth to stop it unwinding — that is the familiar clicking feel of winding a watch. As the spring relaxes it turns the drum, driving the whole gear train.
From the barrel (one turn ≈ 6.7 hours) to the center wheel (1 hour), third wheel, and fourth wheel (1 minute), each mesh speeds rotation up. Center-to-fourth is exactly 60:1 — precisely the ratio of the minute hand to the second hand. The tooth counts (80/12, 80/10, 75/10, 80/8) follow classic standard practice, so the model keeps time with mathematical exactness.
Left alone, the mainspring would unwind in a single burst. The escapement dams that energy and releases it drop by drop. The escape wheel is caught and released by ruby pallet stones, advancing half a tooth per beat (0.2 s). In slow motion you can see the full cycle: lock (dead stop) → unlock (a slight recoil) → leap → slam into the next stone.
The balance wheel and hairspring together oscillate 2.5 times per second (18,000 beats per hour) with near-perfect isochronism: the period stays almost constant even as the amplitude varies. That property is the source of mechanical accuracy. The hairspring's inner end turns with the balance while its outer end is fixed — watch it breathe.
The dial side. The cannon pinion, friction-fitted to the center arbor, carries the minute hand; the motion works reduce its rotation 12:1 to drive the hour wheel and hour hand. The friction fit is what lets you slip the hands when setting the time. The small second hand sits directly on the fourth wheel — its five little steps per second are the escapement rhythm made visible.
A watch is built from the bottom up: jewels pressed into the main plate, barrel and train set in place, bridges screwed down, escapement and balance mounted, the automatic works stacked on top — then the dial, hands and finally the case. Drag the slider to travel that journey in either direction. The movement keeps ticking even mid-air — the moment each part’s role is clearest.
Learn how a mechanical watch works — on a living movement