Watch regulators

Last updated on January 8, 2021

When you begin collecting antique watches you will start prying open the case backs and examining the movement inside. Initially, it is quite bewildering as you peer at the complicated mechanical movement. There are cogs and gears, screws, bridges, makers marks and jewels. Understanding how those components interact is difficult at the beginning. I decided that I would break the components down and take a look at them individually and let my knowledge of the movement grow from there.

Watch components

The watch jewels were the first component I tackled. This is because the first antique pocket watch I acquired had the words “15 jewels” stamped on the movement. I could at least read and understand those words. I could also see some of the pink coloured sapphires peering out from the back of the movement. I decided to start there rather than delve into the complexity of the gear train, balance wheel, escapement or the mainspring.

After I got a basic understanding of the purpose of a jewel bearing in the movement of an antique pocket watch I decided to move on. The next thing I noticed on the back of the movement were the letters F, S, A & R on the bridge sitting above the balance wheel. It didn’t take too much research to find out that these letters represented, Fast, Slow, Avance and Retard (French). Additionally, they were indicators on an adjustable component known as the regulator. Today’s post is a brief overview of what the regulator is and how it works.

Regulator lever.

Regulator

Regulating an antique watch means making it run slightly faster (F/A) or slower (S/R), by making a small change in the effective length of the balance hairspring. The shorter the effective length, the quicker the balance completes its swing and so the watch runs faster. If the effective length is increased, the opposite occurs. In antique watches, this is achieved by moving the regulator lever. Typically, each move along the scale will make the watch run faster or slower by approximately 5 seconds. The regulator lever can be moved using a finger, a toothpick or a match stick. I am not aware of any specific tools for this purpose.

An antique pocket watch that doesn’t have a regulator is considered to be a “free sprung” movement. This type of watch would need a specialist watchmaker to adjust the watch based on position and temperature. At this point in time, all of my antique watches include a regulator lever, but I have not had the need to use it.

Regulation of antique watches

Unless an antique watch is in good mechanical condition and adjustment, it’s really a waste of time trying to regulate it within a couple of minutes per day. By ‘good mechanical condition’ I mean the movement is clean and well lubricated. Additionally, there should be no excessively worn jewel bearings and there are no damaged gear teeth or pinions. It is also very optimistic to expect a low jewel-count (< 15) movement to perform well on a regular basis after over a hundred years of use.

Personally, I have not regulated any of my antique watches because they all run within +/- 2 minutes per day. I was told by an expert that an acceptable timekeeping profile for an antique watch was +/- 5-10 minutes a day, so I wouldn’t consider regulating a watch at all necessary. At most, moving the regulator lever is going to improve your timekeeping by 25 seconds a day, so if your watch is about by minutes, the improvement is negligible. If your antique watch is out by more then 10 minutes a day it is likely to benefit more from a service. I would rather spend the money on a service, which may well extend the life of the movement, than risk damaging an antique hairspring by regulating.

Update: I have recently regulated one of my antique pocket watches, you can read about it in this post.

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