A few questions for the experts ...

Thread: A few questions for the experts ...

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  1. #1
    v76
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    A few questions for the experts ...

    Are higher beat movements easier to adjust and regulate when compared with lower beat movements? I would define "high-beat" as 28,800 vph and higher.

    Are improvements obtained from refinements such as variable inertia and free-sprung balances, Breguet overcoils, etc. more observable with low-beat movements?

    Is there a law of diminishing returns with respect to accuracy (positional and temperature variations, too?) with these refinements as you "up" the beat rate? And, if there is, what is the threshold beat rate?

    I know that variations in timekeeping rates with temperature variation are combated with special alloys for the balance with a low coefficient of thermal expansion, and positional variation with free-sprung balances and Breguet overcoils (isochronism problems with special mainspring alloys or multiple barrels?). Does beat rate also effect positional and temperature variations given all other things are equal?

    I look forward to a lively discussion ...
    Last edited by v76; November 22nd, 2010 at 13:54.
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    Re: A few questions for the experts ...

    Higher beat counts have more increments so if everything else is equal then they should have the capability to be adjusted better. But everything else is not equal, so only on paper are they better. Slower beat count movements can have a larger balance wheel due to the physics of rotational mass (maybe lysander can explain) which can have a more stable oscillation. The single most important factor in accuracy is the consistency of a balance wheel's amplitude. The second most important thing is consistent power delivered to the balance assembly.

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    Re: A few questions for the experts ...

    Quote Originally Posted by v76 View Post
    1) Are higher beat movements easier to adjust and regulate when compared with lower beat movements? I would define "high-beat" as 28,800 vph and higher.

    2) Are improvements obtained from refinements such as variable inertia and free-sprung balances, Breguet overcoils, etc. more observable with low-beat movements?

    3) Is there a law of diminishing returns with respect to accuracy (positional and temperature variations, too?) with these refinements as you "up" the beat rate? And, if there is, what is the threshold beat rate?

    I know that variations in timekeeping rates with temperature variation are combated with special alloys for the balance with a low coefficient of thermal expansion, and positional variation with free-sprung balances and Breguet overcoils (isochronism problems with special mainspring alloys or multiple barrels?). 4) Does beat rate also effect positional and temperature variations given all other things are equal?

    I look forward to a lively discussion ...
    From empirical evidence:

    1) No.

    2) No.

    3) It probably happens at around 18,000 bph, or 2.5 Hz. Advances beyond that beat rate are more likely for aesthetics and resolution (in chronographs/stopwatches.)

    4) No.
    familiaritas parit contemptum; raritate admiratione wins.- Lucius Apuleius
    est necessry, accurate ad secundo? - Lysander magna
    iustum est horologium - Obscurus Genius

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    Moderator Public Forum John MS's Avatar
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    Re: A few questions for the experts ...

    .Are higher beat movements easier to adjust and regulate when compared with lower beat movements? I would define "high-beat" as 28,800 vph and higher.
    No. Ease of adjustment comes from having a properly designed movement and a micrometric adjuster.

    Are improvements obtained from refinements such as variable inertia and free-sprung balances, Breguet overcoils, etc. more observable with low-beat movements?
    Nothing observable. For the most goodies like part free sprung and variable intertia balances are great theoretical concepts but they exist mostly as a way for marketers to differentiate their watches.

    Is there a law of diminishing returns with respect to accuracy (positional and temperature variations, too?) with these refinements as you "up" the beat rate? And, if there is, what is the threshold beat rate?
    In theory the faster beat movement should deliver better results. In practice there have been plenty of 18,000 bph movements certified as chronometers.


    I know that variations in timekeeping rates with temperature variation are combated with special alloys for the balance with a low coefficient of thermal expansion, and positional variation with free-sprung balances and Breguet overcoils (isochronism problems with special mainspring alloys or multiple barrels?). Does beat rate also effect positional and temperature variations given all other things are equal?
    In theory it does. In practice it's not observable.

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    v76
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    Re: A few questions for the experts ...

    Thank you for your answers Dennis, Lysander and John
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    Re: A few questions for the experts ...

    I have a watch with a Unitas (ETA) 6498 movement. It has a beat of 18,000 beats per hour. there are versions of this movement with a 21,600 bph. I was surprised when my watchmaker saw this watch on my wrist, asked if he could see the watch, and then asked if he could regulate it for me. He invited me back into the back of the shop, and he took the movement out and put it on the timing regulating machine. He found that the watch was a bit over +2 sec per day, which surprised me. He then said that the movement could possibly be regulated even better. As he regulated it, I was given a running commentary/lesson on shortening the functional length of the hairspring, and how to zero the balance wheel "peg" within the center of the forks of the pallet fork. Sorry for not explaining all of that with the actual correct horological terms.

    At any rate, the watch does run at just about +2 sec per day. Pretty amazing for a movement designed in the middle of the last century for pocket watches.

    I have 6 examples of this movement, some of which have a beat of 21,600, and they all seem to be about equally accurate.....I love this movement more than any of my other Swiss or Japanese movements.

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    Re: A few questions for the experts ...

    Quote Originally Posted by norm View Post
    the balance wheel "peg"
    I think you mean the impulse jewel, also called the roller jewel.


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    Re: A few questions for the experts ...

    Ulackfocus...Thanks for the clarification on "peg"...Impulse jewel or roller jewel does sound a lot better! But yes, that is the small structure on the balance wheel that I was talking about.

    At any rate, after reading some more after being inspired by this thread, it seems that larger watch movements (especially those with large balance wheels) have an edge over smaller ones in that the larger rotating mass is inherently more stable; stability is a friendly determinant of precise time intervals. And this movement (Unitas 6497/6498) is one of the larger ones being used in wristwatches. I was surprised at the number of expensive watches that are using it. But my lowly Swiss Army Ambassador also benefits from this, as does my O&W XXl

    Just as an aside, I can tell if I am holding the original low beat watch (18,000 bph) or the higher beat version (21,600 b[h) by listening to them. But I can't tell the difference by looking at the movements. I suspect that I might be able to tell if I could see the number of teeth on the gears or the escape mechanism.

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    Re: A few questions for the experts ...

    Quote Originally Posted by norm View Post
    I suspect that I might be able to tell if I could see the number of teeth on the gears or the escape mechanism.
    That's not as easy as it sounds. You might not notice a difference without magnification and a side by side comparison, and even then the teeth are so fine it would be hard to discern any changes from one to the other. Check out the equation towards the end of this link: Horology 101 - wheel train. Minimal changes result in large adjustments to the bph.

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