Is chonograph accuracy driven by the same accuracy as the movement in general?
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Thread: Is chonograph accuracy driven by the same accuracy as the movement in general?

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  1. #1
    Member Drez's Avatar
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    Is chonograph accuracy driven by the same accuracy as the movement in general?

    Bit of a theoretical question here but would the accuracy of a given automatic/mechanical chonograph be determined by the accuracy of the movement itself? i.e. if a Valjoux 7750 is keeping time to +2s/d then the chonograph would also be accurate to the same error as its being driven by the same balance wheel, escapement, mainspring etc. I say this assuming there is nothing slowing or speeding the system up between the shared timekeeping heart of the movement and the gears driving the chronograph.

    I would love the input of someone who knows their mechanical watch anatomy.

    Is this answer different perhaps based on the movement itself i.e. perhaps yes for a Valjoux 7750 or Lemania 5100 but no for the Dubois Depraz modules?
    Collection:

    *Tag Heuer Carrera Automatic Twin Time (WV2115)
    *Omega Seamaster Aqua Terra (2503.33.00)
    *Vintage 1956 Junghans Chronometer Cal. 82/1 (682.73)

    *Sunnto Core Lava Red Positive Dial (SS016788000
    )
    *Casio Super Illuminator (MDV102-7a)
    *Vintage 1983 Seiko SQ (6923-7009)

    *Jaeger-LeCoultre Atmos Cal 528-8 Mantle Clock


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    Member lysanderxiii's Avatar
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    re: Is chonograph accuracy driven by the same accuracy as the movement in general?

    Ordinarily, the rate of a chronograph is dependent on the rate of the balance. So, you will see a timing error in the stop watch similar to the error in hour/minute hands.

    This is true of all chronographs whether integrated or modular.

    That said, if the chronograph is not properly adjusted, you will see a rate change, as drag on the base movement can affect balance amplitude, and thus rate. (Also true of both integrated and modular, but generally, modular chronographs, such as the 2894-2, are more sensitive to poor adjustments in the module.)
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    familiaritas parit contemptum; raritate admiratione wins.- Lucius Apuleius
    est necessry, accurate ad secundo? - Lysander magna
    iustum est horologium - Obscurus Genius

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    Member Drez's Avatar
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    Re: Is chonograph accuracy driven by the same accuracy as the movement in general?

    Quote Originally Posted by lysanderxiii View Post
    Ordinarily, the rate of a chronograph is dependent on the rate of the balance. So, you will see a timing error in the stop watch similar to the error in hour/minute hands.

    This is true of all chronographs whether integrated or modular.

    That said, if the chronograph is not properly adjusted, you will see a rate change, as drag on the base movement can affect balance amplitude, and thus rate. (Also true of both integrated and modular, but generally, modular chronographs, such as the 2894-2, are more sensitive to poor adjustments in the module.)
    Thanks, thats very informative.

    Based on that then, a well adjusted chrono should keep time at the same rate of the base movement while a poorly adjusted chrono can affect timekeeping of the min/hour hands as well as the chrono hands, in other words both top down and bottom up.

    i.e. a watch keeping good time might slow down/speed up with chrono engaged (assuming poor adjustment?)

    Is that correct? Might I extrapolate further and assume that changes in timekeeping with chrono engaged vs. off suggests that service is due?
    Collection:

    *Tag Heuer Carrera Automatic Twin Time (WV2115)
    *Omega Seamaster Aqua Terra (2503.33.00)
    *Vintage 1956 Junghans Chronometer Cal. 82/1 (682.73)

    *Sunnto Core Lava Red Positive Dial (SS016788000
    )
    *Casio Super Illuminator (MDV102-7a)
    *Vintage 1983 Seiko SQ (6923-7009)

    *Jaeger-LeCoultre Atmos Cal 528-8 Mantle Clock


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    Member lysanderxiii's Avatar
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    Re: Is chonograph accuracy driven by the same accuracy as the movement in general?

    Yes, the rate of the stop watch portion are alway the same as the rate of the time portion.

    Does it indicate a service is due? Not really, some places don't do a very good job adjusting chronographs at the factory or they get out of adjustment during casing. And, once adjusted, they really should not drift, they are mostly positioning stop locations.
    familiaritas parit contemptum; raritate admiratione wins.- Lucius Apuleius
    est necessry, accurate ad secundo? - Lysander magna
    iustum est horologium - Obscurus Genius

  6. #5
    Member Drez's Avatar
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    Re: Is chonograph accuracy driven by the same accuracy as the movement in general?

    Excellent. Thanks for sharing your knowledge!
    Collection:

    *Tag Heuer Carrera Automatic Twin Time (WV2115)
    *Omega Seamaster Aqua Terra (2503.33.00)
    *Vintage 1956 Junghans Chronometer Cal. 82/1 (682.73)

    *Sunnto Core Lava Red Positive Dial (SS016788000
    )
    *Casio Super Illuminator (MDV102-7a)
    *Vintage 1983 Seiko SQ (6923-7009)

    *Jaeger-LeCoultre Atmos Cal 528-8 Mantle Clock


  7. #6
    Member JAYMAC10's Avatar
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    Re: Is chonograph accuracy driven by the same accuracy as the movement in general?

    Great question and great answer!

    Cheers,

    Jay

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