Little about the mechanism
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  1. #1
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    Little about the mechanism

    Hi all.

    I am new, so regards to all good people here.

    I am interesting about two things.

    Why the gears of the time train are of different material then others? And which material is it?

    Second about main spring and barrel. What controls, or how, the force of the spring to the escapement? If the spring has different power, how the force is constant on the time train?

    Hope this is understandable question. I mean I was clear enough.

    Best regards all.

  2. #2
    Member pithy's Avatar
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    Re: Little about the mechanism

    Quote Originally Posted by Split sec View Post
    . . . . . . I am new, so regards to all good people here. . . . . .
    This thread has potential . . .

    Quote Originally Posted by Split sec View Post
    . . . . . . I mean I was clear enough. . . . .
    Yep. Instant classic.

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  3. #3
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    Re: Little about the mechanism

    Second about main spring and barrel. What controls, or how, the force of the spring to the escapement?



    How a Watch Works
    Last edited by watchma; November 3rd, 2013 at 17:27.

  4. #4
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    Re: Little about the mechanism

    Nice. Thanks.

    So, in the range of force when the spring is full till end, the force is irrelevant?

    OK. What about materials?

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    Member LCheapo's Avatar
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    Re: Little about the mechanism

    Quote Originally Posted by Split sec View Post
    Why the gears of the time train are of different material then others? And which material is it?
    Than other gears? Or other parts of the watch in general? From what I've read, wheels are mostly brass, and pinions steel, to keep the wear down on the fewer leaves of the pinions.

    Quote Originally Posted by Split sec View Post
    Second about main spring and barrel. What controls, or how, the force of the spring to the escapement? If the spring has different power, how the force is constant on the time train?
    The torque on the train is not constant as the mainspring unwinds, unless the watch has a special mechanism (a fusee and chain, or a periodic defined torque transfer gizmo, as in the Lange 31) for it. So the balance amplitude will change with the winding state of the mainspring.

    There are some interesting books and free electronic documents out there that will help with general questions. Freely available watch catalogues, like from Lange or IWC or Jaeger-LeCoultre, also contain some technical detail with nice pictures and drawings. See
    TM 9-1575 – I Already Have a Watch. and [Catalog] All the watch catalog I've ever found on the internet : Watches
    pithy likes this.

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    Re: Little about the mechanism

    Well, it is obvious that torque force is descending. I am not interesting in details, but when they start to project a watch, do they start with escape wheel and force needed on it or vice verse, what they have on the spring. I am just curious.
    And to keep the wear down on the fewer leaves of the pinions is strange reason. ( English is not my mother tong, perhaps I do not understand this). Steel should last longer?
    But thank you for kind explanation. I shall look on the links.

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    Member jesse1's Avatar
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    Re: Little about the mechanism

    The use of two different metals reduces the chances of binding and adhesion due to rust , electromagnetism , etc... . Also the Zinc in the brass almost acts as a lubricant (over simplified explanation).

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    Re: Little about the mechanism

    Yes it is relevant. Any modern watch will speed up as the mainspring winds down, this is due to less amplitude delivered to the hairspring/balance wheel per stroke as the spring winds down due to Hooke's law, making every 'beat' shorter, increasing the rate of the watch. You can measure the decrease in amplitude on a timegrapher, sometimes as much as 50 degrees. This is your 'isochronism' error quoted on your movement's specifications. However with modern mainspring materials like Nivarox and impulse pin design this isochronal error is usually less than 10 seconds a day in reality. There are of course attempts to allow constant force to be delivered by a mainspring that follows Hookes' law, like the Girad-Perregaux constant force escapement watch, but those cost about the same as a supercar.
    Quote Originally Posted by Split sec View Post
    Nice. Thanks.

    So, in the range of force when the spring is full till end, the force is irrelevant?

    OK. What about materials?
    Last edited by yifu; November 4th, 2013 at 13:23.

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    Re: Little about the mechanism

    If you were designing a watch, you'd probably start with the balance wheel and figure out how much force you need for the balance wheel to have a proper amplitude. This will be a function of the size and weight of the balance, which will require a certain size and strength of hairspring. The design, layout and tolerances of the escapement and gears will impose a loss of force that also has to be accounted for, so at the end of the process you'll need a particular mainspring to deliver the force required.
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  10. #10
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    Re: Little about the mechanism

    Now it is little clearer to me.

    So, if you would take, just for example, 7 day power reserve and limit just to use fourth day power, than the difference in power should be minimized. But I have a watch running one sec per day ahead. What happend with this? There must be something minimizing this difference or it is not so big (10 sec/day) Is adjusting the palet solving it? Or it is becouse selfwinding take it always (mostly) full wind? And "constant" power?
    Last edited by Split sec; November 4th, 2013 at 13:23.

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