The other sort of beat error?

AlecMac · April 14, 2023

Good morning,

I was sitting in the bath yesterday day dreaming about Swiss Lever escapement...we all do that right?..I was picturing what happens when the balance spring isn't centred between the regulator pins. In my mind the spring was in contact with a pin on one half of an oscillation, then pulled away for the other half.

My question is, would having the watch running with effectively different length balance springs for each half of an oscillation show as a beat error? Or to put it another way, can adjusting the regulator pins seem to introduce a beat error?

All the best

Alec

fellerts · April 14, 2023

I should imagine so!

In this scenario, I believe you should see significant rate differences between low and high amplitude as well, which I guess is one way to detect this particular fault. Let's imagine the outer regulator pin having broken off or being bent way out of shape. If the spring rests on the inner pin at low amplitudes, it will spend a lot of time in "free air" when the amplitude increases, effectively increasing its length, slowing down the rate. This problem would perhaps even be exacerbated in some vertical positions, because gravity will help pull the spring out from the inner regulator pin.

This is why the literature is so adamant that the balance spring should rest perfectly between the regulator pins and have very little "slop" to move about between the pins (the gap should be around 2x the thickness of the spring if I remember correctly). It's also important that the spring follows the arc of the regulator pins as perfectly as possible.

mikepilk · April 14, 2023

29 minutes ago, fellerts said:

If the spring rests on the inner pin at low amplitudes, it will spend a lot of time in "free air" when the amplitude increases, effectively increasing its length, slowing down the rate. This problem would perhaps even be exacerbated in some vertical positions, because gravity will help pull the spring out from the inner regulator pin..

Good point. I've tended to adjust the spring so that it just rests against the inner pin. That might explain why I sometimes get a big variation between horizontal and vertical rates.

Neverenoughwatches · April 14, 2023

38 minutes ago, fellerts said:

I should imagine so!

In this scenario, I believe you should see significant rate differences between low and high amplitude as well, which I guess is one way to detect this particular fault. Let's imagine the outer regulator pin having broken off or being bent way out of shape. If the spring rests on the inner pin at low amplitudes, it will spend a lot of time in "free air" when the amplitude increases, effectively increasing its length, slowing down the rate. This problem would perhaps even be exacerbated in some vertical positions, because gravity will help pull the spring out from the inner regulator pin.

This is why the literature is so adamant that the balance spring should rest perfectly between the regulator pins and have very little "slop" to move about between the pins (the gap should be around 2x the thickness of the spring if I remember correctly). It's also important that the spring follows the arc of the regulator pins as perfectly as possible.

As you rightly say fellerts the spring should sit inbetween the pins with a half a spring width either side. With the spring breathing spending equal amounts of time on either of the pins rather than mostly centered which would allow its active length to run back to the stud and slow time keeping. If the pins were too tight then i guess the beat would alter as the spring's active length and held length becomes the same, eliminating the stud's effect on beat. Wouldn't that push the balance and roller jewel more over to one side ?. So important to have that pin spacing correct so that the spring sits center of them as it reaches its neutral point of rest as the roller jewel lands center of the pallet fork. Too much thinking has made my head a bit fuzzy now lol.

JohnR725 · April 14, 2023

43 minutes ago, mikepilk said:

Good point. I've tended to adjust the spring so that it just rests against the inner pin. That might explain why I sometimes get a big variation between horizontal and vertical rates.

one of the first shops I worked at the owner recommended or his suggestion was tight against one of the regulator pins which makes logical sense unless something happens. Like too much amplitude.

4 minutes ago, Neverenoughwatches said:

As you rightly say fellerts the spring should sit inbetween the pins with a half a spring width either side.

this is the rule for flat hairsprings. They need a little bit of breathing room. If it's in over coil spring then the pins have to be as tight as possible but still allow the hairspring the slide.

then I have an image for you the effect of the regulator pins a necessary evil if you would like to regulate the watch conveniently but beyond after a pain in the ass and be nice if we could just break them off and not have them at. Because as because plainly obvious timekeeping is affected by amplitude with the regulator pins.so if your hairspring is between the regulator pins which is where it's supposed to be ill have even timekeeping at least above a specific amplitude. The farther the pins are a part the worse this effect becomes. Then for whatever reason flat hairsprings need their breathing room so closing a really tight will have some unknown consequence. Yes everything has a consequence. In the case of an over coil hairspring those pins are just a little bit apart you can dramatically see the effect of going from a dial position to a pendant position the watch will slow down. And that's where is mostly all my pins are too far apart and that I tighten them and in the problem goes away hopefully.

Then what if you're touching one of the pins as you can see it has a very different type of timing curve. This example if you are regulated for zero seconds resting on a pin everything would be fine until amplitude picks up enough that it lifts it off the pin.then the exact nature the curve will depend upon the pins spacing. Initially as you lift off you'll be slow very slow because the regulation point is now at the stud. Providing the other pin was within distance of the hairspring finally able to touch that then you end up with some point in time with the flat average at the higher amplitudes.

2 hours ago, AlecMac said:

My question is, would having the watch running with effectively different length balance springs for each half of an oscillation show as a beat error? Or to put it another way, can adjusting the regulator pins seem to introduce a beat error?

theoretically I suppose anything is possible but I'm going to say no. But you can get some interesting beat error changes by going to crown/pendant positions. This is because as the hairspring sags because the effect of gravity it rotates the balance wheel and that causes a beat error. Also things like hairspring is not centered can cause beat errors.

oh and if you're into this kind of thing is a video where it talks about a really interesting book. Plus if you find the book interesting the second link is where it can be purchased.

https://youtu.be/op68gwVvsCo

https://www.booksimonin.ch/home.php