FINGER

In watchmaking, the finger is a small stud, generally integral with a rotating element — wheel, pinion or cam —, intended to intermittently drive another component. With each lathe, the finger catches a star (wheel) or a set of teeth to advance an indicator by one step: counter for the minutes of a chronograph, disc for the days or the date, indication of date / calendar. This training mode transforms continuous rotation into a movement jerky motion, essential for the operation of displays that progress notch by notch. The finger most often works in conjunction with a star (wheel) and a neck chain (sautoir), the latter ensuring the position is maintained between two jumps. Its shape, position, and timing of action are precisely calculated, as a poorly adjusted finger causes incomplete jumps, jamming, or an display imprecise. Modest in size, the finger is a key element of mechanisms with discontinuous display.