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Believe it, the Seamaster actually RAN!

  1. Canuck Dec 1, 2019

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    One of the collector fraternity asked me to check out his Seamaster. It was keeping lousy time, and kept stopping on the watch winder! An initial quick look yielded no obvious problem. The auto wind was working. The manual winding felt odd. So I decided to check the mainspring. See what you think.

    CA00BADC-22D7-4B90-B8C0-8E0FE500196C.jpeg
     
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    Edward53, Longbow, Deafboy and 6 others like this.
  2. henrikaa Dec 1, 2019

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    :) Seems like you sorted the problem with the mainspring. So now it winds?
     
  3. Canuck Dec 1, 2019

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    The owner of the Seamaster just sent me these pictures, 18 hours after the job was finished, and the watch back on his wrist. Little doubt it will be right as rain, now. In all my years of doing this, I have never seen a mainspring “shatter” the way this one did. It was an original “unbreakable” mainspring!
     
    MJKauz likes this.
  4. henrikaa Dec 1, 2019

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    What do you think the likely cause could be to the shattering? Overwinding, metal fatigue?
     
  5. Canuck Dec 1, 2019

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    Overwinding? As much as I dislike the idea of keeping a horse on a treadmill between times you want to ride him, the watch ran fine on the watch winder until things changed. So overwinding would not have been a factor. Metal fatigue affects all metals to varying degrees, depending on the alloy. I suspect this particular spring was fully wound when it broke in one spot. In a nano second, as the pent up energy of the wound spring was released, all the other fractures happened.
     
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  6. Archer Omega Qualified Watchmaker Dec 1, 2019

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    Never seen this with a modern alloy spring, but not unusual with blued steel spring, like this one:

    [​IMG]

    As for the causes, I suspect this is some defect in the initial manufacturing of this spring. Can't say if it's inclusions in the alloy, some sort of heat treatment failure, or what, but it certainly is unusual...

    Cheers, Al
     
  7. Canuck Dec 1, 2019

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    Looks like a Waltham mainspring barrel, and probably an original blued steel mainspring. Even if that spring is a replacement, it has to be 60 or 70 years old. Metal crystallizes with repeated flexing. I have known those old steel mainsprings to have lain dormant for decades, either in a watch, or in the original Waltham package, to snap within a few days after being pressed back into service. I replace them with a modern alloy spring, even if they aren’t broken.
     
  8. Archer Omega Qualified Watchmaker Dec 1, 2019

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    For the old blued springs, they don’t require repeated flexing to fail like this. I’ve seen them shattered in new condition, never installed, and still bound up with wire from when they were manufactured. Such failures can come from things like hydrogen embrittlement...

    Most certainly blued steel springs should be replaced no matter the condition.

    The failed white alloy spring is again most likely some sort of manufacturing defect.
     
    DaveK and kkt like this.
  9. Canuck Dec 1, 2019

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    I have known those old steel mainsprings to have lain dormant for decades, either in a watch, or in the original Waltham package,

    And I quote myself. Yes, I am aware they have been known to fail without ever having been in a watch.
     
  10. Archer Omega Qualified Watchmaker Dec 1, 2019

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    Here’s the full quote, just for completeness sake...