Adjust / Regulate

To adjust or more commonly expressed as regulate. To regulate time-keeping through the adjustment of a watch movement though specialised tools and manipulations.

Adjustment or regulation can be used in relation to multiple aspects of watchmaking, below the term is associated with the basic ways by which balances are adjusted in the pursuit of accurate time keeping. The subject is large and complex here is shown only two of the most basic elements.

Balances that are adjusted by altering the effective length of a balance spring through the use of an index and secondly, those that alter evenly the position of weight on the periphery of the balance, namely free-sprung balances.

The shorter the balance spring the faster the rate, the longer the balance spring, the slower. Below an example of an Omega from the 1990’s with index. The index is adjusted either manually with tweezers or through turning the eccentric plug which is in the centre of the index. The underside image shows the pin and ‘boot’ which are fixed to the index and effect the length of the balance spring as it is turned.

The first image is from a Rolex, the second a modern Breguet calibre. Both are free-sprung, implying neither has an index and the regulation is executed by evenly altering the position of the weights around the circumference of the balance wheel. If the weights are screwed in, towards the centre the timing will accelerate and if moved further outwards, the rate will slow down.

The advantage of free-sprung balances over those regulated with indexes with regulating pins is the removal of one of the possible elements that introduces an error to the mechanism and can effect isochronism.