We’re all watch enthusiasts here, right? Would be nice if you wouldn’t have to go to your watchmaker for every little thing. Especially when you have a bigger collection it could save time and potentially money as well. This article is on how to regulate a watch and specifically on how to correct the rate.
What is the rate?
Your mechanical movement has a set of gears, called the train wheel and this is powered by the mainspring. The last gear in this train is the escape wheel. The pallet fork locks and unlocks the escape wheel so the train wheel advances the required amount.
When the gears in the train wheel turn too fast, the watch will be gaining time and when they turn too slow it will be losing time. The rate, therefore, is actually the frequency of the pallets locking and unlocking the train wheel. This can be adjusted with the balance.
The balance has several parts but the most important for the rate are the balance wheel, the hairspring and the impulse pin. The balance wheel swings left and right with the help of the hairspring and with every pass, the impulse pin will engage with the pallet fork to advance its position. You can imagine that with a longer swing the pallet fork will be engaged less so the rate will drop. Of course, the opposite is also true.
How to measure the rate?
There are several ways how you could measure the rate. One is to synchronize your watch with an accurate clock (perhaps a radio-controlled clock or the clock on your computer). Come back after 24 hours and look for any time gained or lost. This method is not the most reliable but if you have no other options, it could work.
Another way is to time your watch with a digital stopwatch, could even be an app on your smartphone. Check after 10 minutes and multiply the result with 6. Now you know the discrepancy per hour. You will agree that this method is even more unreliable than the previous one.
The most accurate way would be to use a timing machine. Either a Swiss one (Witschi or similar) or an Asian one (Timegrapher or similar).
The Swiss timing machines are of a better quality and are more precise. They also have more options to select and display and are therefore the obvious choice for professionals. For an amateur or hobbyist, however, a Timegrapher from Ebay is an excellent choice to measure and display the rate.
A Timing machine “listens” to the vibrations in the movement and translates them into lines of dots. Lines that have an upward angle show that the watch is gaining time and a downward angle indicates the watch is losing time.
How to correct the rate?
As mentioned, the rate is the speed in which the pallet fork locks and unlocks the train wheel. With every passing of the balance wheel, the impulse pin engages and releases the pallet fork to push it into the next position. That means that a shorter swing will cause the watch to run faster and a longer swing will do the opposite. A shorter swing can be accomplished by shortening the effective length of the hairspring. This can be done with the regulator.
The regulator has two regulator pins which guide the first winding of the hairspring. Moving these pins towards the stud (the beginning of the hairspring and secured to the balance cock) will effectively lengthen the spring. This will make the watch run slower and moving the regulator away from the stud will make the watch run faster.
Some final advice
- Don’t fret on a couple seconds. Everything between 0 and +10 sec per 24 hours is very good. I understand that you want to come as close to 0 as possible. Remember that not all movements can be regulated perfectly, especially vintage timepieces. Often you have to compromise.
- Move the regulator very gently and slowly. If the hairspring gets caught between the pins while you keep pushing, you’ll bend and kink it. That will ruin the hairspring and that’s a showstopper for your watch.
- Please be careful to manipulate the regulator and not the mobile studholder (if it has one). If you manipulate the mobile studholder you’ll be affecting the beat error and that can’t be corrected without a timing machine.
Did you find this article useful to correct the rate of your watch yourself? Feel free to share it with your friends who you think might benefit from this article as well.