Relationship between beat error and rate?

Thread: Relationship between beat error and rate?

1. Relationship between beat error and rate?

I've been playing with my new MicroSet timer on a 3133 movement. The watch is nearly new but it was way off, but I managed to get the beat error down to 0.8 ms and the rate to around +4.0 sec/day.

It seems like if I adjust the rate, the beat error changes slightly, so I wondered if there is a relationship between the two?

Also, what is a "good" beat error -- I suspect zero is best, but is 0.8 ms acceptable?

One more question: The 3133 is rated at 21,600 bph. So is there a relationship also to how fast or slow the watch will run and how close to the 21,600 bph I can get it? In other words, if it's running say 21,610 bph, does that mean it will run + seconds per day?

Thanks!

2. Re: Relationship between beat error and rate?

I think you'll find that the only reason the beat error changes when you adjust the rate, is because the hairspring changes shape slightly, so that the average position (or position with no power) of the roller jewel in the pallet fork changes slightly. To get a beat error of zero, the jewel must be perfectly centered. If it moves at all from that center, you have a beat error.
We were taught that anything below a 1ms beat error is acceptable. With old pocket watches, I think you'll find that as long as it starts on it's own, it's good enough.

"One more question: The 3133 is rated at 21,600 bph. So is there a relationship also to how fast or slow the watch will run and how close to the 21,600 bph I can get it? In other words, if it's running say 21,610 bph, does that mean it will run + seconds per day?"
Absolutely. In fact, that is exactly how the gain or loss is calculated. The microset counts the number of beats then compares it to the rating - in your case 21,600bph, and it uses the difference to calculate the gain or loss in seconds per day. If it runs slower than 21600, then you're losing time, if it runs faster, you're gaining time. I think you'll find that if you could get it to run at exactly 21600 bph, then your gain or loss in seconds per day would register as "zero".

I see I had the wrong formula- I believe lysanderxiii is correct.

I've had watches that registered under 1 second per day gain or loss.

3. Re: Relationship between beat error and rate?

Originally Posted by Sodiac
One more question: The 3133 is rated at 21,600 bph. So is there a relationship also to how fast or slow the watch will run and how close to the 21,600 bph I can get it? In other words, if it's running say 21,610 bph, does that mean it will run + seconds per day?

Thanks!
21,600 bph = 518,400 beats per day and 6 beats per second.

21,610 bph = 518,640 beats per day, or an additional 240 beats.

Comparing the 6 beats per second to the additional 240 beats each day we get an extra 40 seconds counted during the day, or the watch is +40 seconds per day.

Or to save time and math work, on the MicroSet, while it is in timing mode, and displaying the rate in bph, push the "Begin/Option" button and " Show Error/Day" will display press the "Plus" button once [1] and "Target: 21600" will display (or the closest standard rate, 18,000, 21,600, 28,800, 36,000), then push the "Begin/Option" button. The next reading will be displayed in S/D....
_____________________________
Notes:
1. If you push the "Plus" button twice the target rate will be the last rate measured, in this example 21610. pushing the "Plus" and "Minus buttons will raise or lower the target rate by one for each push. This is in case you have a weird beat movement such as 19,800 or 25,200 bph movement.

4.

5. Re: Relationship between beat error and rate?

Thanks guys, I'm learning something new all the time, that's good!

So is there a better way of manipulating the adjustment bars? When you get down to plus or minus 0.5 ms movements or plus/minus 5 bph, it's pretty tough. Or, do you just try to push one way and another until you happen to hit a magic place? Is there some type of tool to make more accurate movements of the adjustment bars?

6. Re: Relationship between beat error and rate?

It's usually best to use something that won't mar the plates. You could use whatever you like, as long as you use care. With some watches, there is no easy way. With many watches it seems one must continuously overshoot the mark, and then try again. There are some watches that have a small adjustment screw that can be turned slowly, and these tend to be a little easier to adjust.
I've been told that mechanical Omega's are supposed to keep time to about 12 seconds a day, off the shelf. Rolex's are expected to keep time to about 3 seconds a day. Most mid-grade wristwatches from the 60's and 70's are doing pretty well if you can get between 30 seconds and a minute a day. It's always possible to do better, but you have to ask yourself, "is it worth the effort"?

7. Re: Relationship between beat error and rate?

Don't get too hung up on the beat error, it is not as critical as the rate. Wostep taught us to adjust beat error to .5 ms. The rate you wish to adjust to the average best of several positions. You may be able to get a watch regulated to 1 sec/day, but turn it over and discover a different error. Check with the pendant up and another error. Do five of the positions and average them. If you don't like it start over until you get an acceptable rate average. Of course as soon as the mainspring winds half way down you will discover very likely the rate has changed again. Go shovel the snow in 10 degree weather and you may see another rate. Five years from now, when the lubricants have evaporated or turned to crud you likely will see another change as friction starts to make an effect. The name of the game is isochronism or the ability of a watch to maintain equal time under any condition. Conditions being things like friction, temperature, magnetism, position, and others.

8. Re: Relationship between beat error and rate?

Thanks again guys, I notice on this watch also (photo below), it will vary a bit when I'm wearing it. It doesn't seem to like the face-up position very much either for some reason. Right now I've been wearing it all day and it's running +3 seconds fast from when I messed with it this morning 9 hours ago, so not too bad.

Maybe I'll leave it crown up on the dresser tonight and see if it slows it down enough to even out in the morning. Close enough though at this point I think, and much, much better than it was before, after I, um, "adjusted" the wrong lever!

9. Re: Relationship between beat error and rate?

Originally Posted by Sodiac
Thanks guys, I'm learning something new all the time, that's good!

So is there a better way of manipulating the adjustment bars? When you get down to plus or minus 0.5 ms movements or plus/minus 5 bph, it's pretty tough. Or, do you just try to push one way and another until you happen to hit a magic place? Is there some type of tool to make more accurate movements of the adjustment bars?
Older movement have a fixed stud lever. You had to dismantle the movement and adjust the position of spring relative to the balance. If I get less than 0.8 ms, I'm happy.....

10. Re: Relationship between beat error and rate?

I still do not understand how beat error affect the rate.
A watch can do exactly 21600bph and have 2ms of beat error, in this case, does beat error affect the rate?
Thanks

11. Re: Relationship between beat error and rate?

Originally Posted by sblantipodi
I still do not understand how beat error affect the rate.
A watch can do exactly 21600bph and have 2ms of beat error, in this case, does beat error affect the rate?
Thanks
Beat error and rate are independent measurements. So you can have zero beat error when the rate is very wrong, or a perfect rate with substantial beat error (as long as the watch is still running).

But the two adjustments can interact. If the movement has an adjustable stud holder and you use it to adjust beat error, the rate adjuster has to move exactly the same amount as the stud holder (in order to keep the free length of the hairspring the same) to keep the same rate. If you move the stud holder but not the rate adjuster, the rate will change.

(Are there any rate adjusters that mount on the movable stud holder, so both automatically move together for beat adjustment?)

On the other hand, as lysanderxiii says, old pocket watches were adjusted for beat by rotating the hairspring collet on the balance staff. That shouldn't change the rate.

- Dave

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