Last updated on November 2, 2024
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. In this instance, I will focus on watch regulators.
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. Additionally, 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
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. However, I have not had the need to use it.
Types of regulator
Tompion regulator
The Tompion regulator consists of a curved rack and pinion mechanism. One end of the rack holds two curb pins that grip the spiral balance spring. Adjusting these curb pins along the balance spring changes its effective length, thereby altering the watch’s rate. To move the rack, a key is applied to a square projection on the pinion and turned. Turning the pinion clockwise moves the curb pins away from the stud, shortening the effective length of the spring and making the watch run faster. Conversely, turning the pinion counter-clockwise moves the curb pins towards the stud, lengthening the spring and slowing the watch.
Bosley regulator
A regulator with a simple straight lever (example above), often referred to as a Bosley regulator, was invented and patented by Joseph Bosley in 1755. This design became the foundation for almost all subsequent watch regulator mechanisms.
In the Bosley regulator, a circular-sectioned lever is mounted on the balance cock and pivots along the same axis as the balance staff. The underside of this lever holds two curb pins (not visible in the image), which grip the outermost coil of the balance spring. The extended part of the lever sits over a graduated, non-calibrated scale, providing a visual reference. This scale, sometimes made from materials like sterling silver, indicates how adjusting the lever affects the speed of the watch. The lever can be manually adjusted, with “Fast” and “Slow” engraved on the plate to indicate the direction of adjustment for regulating the timekeeping.
Micro regulators
Making precise adjustments with a standard watch regulator can be challenging, as even small movements of the lever can cause significant changes in the watch’s daily rate. To improve the accuracy of these adjustments, various devices have been developed over the years, designed to allow finer control over the lever’s position. These mechanisms often involve either a screw or a cam that can be rotated incrementally, moving the lever in tiny, precise steps. Regardless of the specific design, these innovations are collectively known as “micro regulators,” and their primary purpose is to enable highly precise regulation of the watch’s timekeeping.
Reed’s Whiplash regulator
In 1867, American inventor George P. Reed patented an enhancement to the Bosley regulator (US patent No. 61,867, dated February 5, 1867). This innovation featured a precision adjuster for the regulator lever, incorporating a spring that curved around the lever to bias it in one direction. A screw was then used to move the lever in the opposite direction against the spring. Reed’s improvement allowed for finer adjustments to the regulator than could be achieved by simply moving the index lever with a finger or screwdriver tip.
Today, Reed’s regulator, with its spring and precision adjustment, is commonly known as a “swan’s neck regulator” or swan neck device, named for the curved spring’s resemblance to a swan’s neck.
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. If your watch is about by minutes, the improvement is negligible. If your antique watch is out by more than 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.
How to regulate an antique watch
Note: if you have no experience working with antique watches, it may be best to consult a professional watchmaker.
Open the case back of the watch carefully, which might require a special tool, especially if the case back is screwed down.
The regulator is typically a small lever or screw on the balance cock of the movement. Usually, it will be marked with “F/A” (fast) and “S/R” (slow).
To Slow Down the Watch: Move the regulator lever towards the “S” or “R” mark. This increases the length of the balance spring, causing the watch to run slower.
To Speed Up the Watch: Move the regulator lever towards the “F” or “A” mark. This shortens the balance spring, causing the watch to run faster.
Some movements have a fine-tuning mechanism in the form of a screw or “swan neck”, in which you can turn the screw clockwise or anticlockwise to achieve the same result.
Make small adjustments and then test the results
Adjust the regulator in very small increments. Even a tiny movement can significantly affect the timekeeping of a watch. After adjusting, close the case back and wear the watch for a day or two to see how it performs. You might need to make further adjustments to get the timing just right.
Update: I have recently regulated one of my antique pocket watches, you can read about it in this post.
A list of additional posts regarding antique watches can be found on the Guides page.
