Regulation

In watchmaking, regulation is not a single operation: it is a family of technical solutions that act on different levels of the movement, with radically different objectives and tools. It is worth distinguishing them clearly, because confusing them is one of the most common mistakes even among enthusiasts.

At the deepest level there is the regulation of the oscillator. The frequency of the balance wheel is controlled by acting on its inertia: the screws eccentrically mounted on the shoulders — the masselottes — shift the mass and modify the moment of inertia without touching the hairspring or the balance cock. This is the logic of the variable inertia balance, present both in high-end calibers and in certain mid-range movements that borrow the solution. The hairspring, for its part, has its own geometry of regulation: the Breguet curve on the outside — the Phillips overcoil — and the Grossmann curve on the inside work together to make the oscillations isochronous regardless of amplitude. Anyone who has seen a 216TMZ caliber on the workbench knows how difficult that geometry is to correct when someone has worked on it without understanding it.

One level up there is the fine regulation of the rate of march through the goose-neck regulator: a spring blade that holds the regulator slide with controlled elastic pressure, preventing the accidental shifts that are frequent on a straight regulator. You find it displayed on the dial of certain contemporary watches not for vanity, but because it is a component worth showing.

Then there is the regulation of the hour, which comprises very different systems. Hacking — the stop of the seconds when you pull the crown — is the foundation: it locks the balance wheel and allows synchronization to the exact second. The stop-seconds of pilot watches is its historically most rigorous version. The quick-change of the hours allows you to move the hour hand in increments without losing the minutes reading, essential when changing time zones. The GMT caller adds an independently adjustable 24-hour hand, so the home reference remains untouched. Grand Seiko's Spring Drive solves the regulation problem with completely different logic: an electromagnetic brake governed by a quartz movement slows or accelerates the tri-synchro wheel to continuously correct the rate, with a visual result — the smoothness of the seconds hand — that resembles no other mechanical system.

At the most sophisticated level there are the mechanisms that protect the oscillator during regulation itself: the stopping of the tourbillon with zero-reset of the small seconds hand in the Calibre L102.1 is the most rigorous example I know. Stopping a tourbillon without damaging it requires a specially patented solution. Constant force, on the other hand, does not regulate the hour but regulates the energy: interposed between the barrel and the escapement, it ensures that the impulse to the oscillator is always uniform regardless of the tension of the spring.