Hamilton 917 running very fast

Thread: Hamilton 917 running very fast

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  1. #1
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    Sep 2012
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    Hamilton 917 running very fast

    Hey all, I just received a watch in trade from a friend, it's a Hamilton 917 movement in a wristwatch case. I like it quite a bit, but it's running very fast, to the tune of +3 minutes an hour. The power indicator also never hits the full mark, it gets about 3/4 of the way there though. When winding it seems to be fairly sturdy, no grinding or anything to speak of, it just stops eventually as I believe it should when fully wound.

    Before I got the watch it had been sitting unwound for some time, perhaps a few months. Prior to that it ran well and the owner was winding it up every morning.

    I'm looking for some advice on how to get it running properly. Will it need a cleaning or a more thorough service?

    Thanks!

  2. #2
    Member AbslomRob's Avatar
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    Re: Hamilton 917 running very fast

    If you watch the balance wheel, can you detect how far it's rotating? A "healthy" balance should rotate 270 degrees or more on a full wind. If it doesn't seem to be moving that much, chances are the movement needs to be cleaned and serviced, or the mainspring needs to be replaced. If it looks like it's got a healthy swing, watch the hairpsring carefully to see if it looks like the coils are touching at any point. The rate of the watch is influenced by the "length" of the hairspring (which is how the regulator arm is able to affect the rate the way it does). If the coils touch at any point, that effectively "shortens" the hairpsring, which will make it run fast. If that's the case, it could be caused by magnetism, or dirt on the hairspring. A good loop demagnetizer might fix it, otherwise it'll need service.

    The power indicator sounds like it just wasn't assembled correctly when it was last serviced. From what I can understand, those things are pain in the rear at the best of times, but I've never worked on one, so I can't really say.
    My growing collection of "affordable" vintages: http://www.abslomrob.com

  3. #3
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    Sep 2012
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    Re: Hamilton 917 running very fast

    The balance wheel is moving about 180* at most. Sounds like that's the cause of it running so fast. Any idea who I could send it to for service/how much it would cost? I don't know of anyone locally.

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