Unusual watch malfunction | FerrariChat

Unusual watch malfunction

Discussion in 'Fine Watches, Jewelry, & Clothes' started by drgek, Oct 7, 2020.

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  1. drgek

    drgek Formula 3

    Jun 21, 2004
    1,142
    Full Name:
    Gary
    I have a two month old watch from a high-end brand (I'd rather not disclose which one) that has a moonphase as a complication. The watch is kept on a winder and keeps excellent time. However, the moonphase advances at twice the rate it should; it will go from full moon to new moon in a week. I can't for the life of me imagine what would cause that except the wrong gear being put in. Obviously, it's going back for warranty service but I must admit I'm curious as to how that is even possible. Any ideas?
     
  2. thphon

    thphon Rookie

    Oct 9, 2019
    30
    Full Name:
    Leonardo Arias
    wow, that's crazy! So it went from being accurate for roughly 126 years as the high end usually are to mess it up the first week...
     
  3. ylshih

    ylshih Shogun Assassin
    Honorary Owner

    Mar 21, 2004
    19,809
    Northern CA
    Full Name:
    Yin
    Without specifying the watch, we have to assume it's a typical moonphase watch. That means it has a moon dial that has two moons that are 180 degrees apart with the dial mated to a 59 tooth gear. The 59 tooth gear is advanced one tooth every 24 hours. This results in a new moon => full moon => new moon display twice per rotation of the 59 tooth gear. Since there are two full moons for every full rotation of the dial, that means a single lunar cycle takes 29.5 days (which is an approximation as the lunar cycle is closer to 29.53 days). There is a 135 tooth gear design that gets closer to the 29.53, but we don't need to get into that as it doesn't add anything to the conceptual model.

    However a typical watch gear train operates on a 12 hour cycle, so that means that there has to be gear pair somewhere that has a 2:1 tooth ratio to convert to days. That function might be readily available if the watch has a day or date function as well, so that there is already a tooth advancement or claw that operates once per day.

    For the watch to keep good time, but for the moonphase to operate at twice the rate, full moon to new moon in 1 week rather than 2.11 weeks, that would imply the moon dial is advancing on the 12 hour schedule rather than the 24 hour schedule. That might happen if the 12 hour to day conversion had a 1:1 ratio rather than a 2:1 ratio; but it's kind of hard to see how they wouldn't see that when they fit the gears together as the spacing/engagement of the gears would be off. If the gears are correct, but one of the gears wasn't properly sized to the arbor (shaft) and the gear is slipping on the shaft (these are usually friction fit), that might not give the correct ratio; but that failure seems more likely to skip than go too fast?
     
    PJxxx, Island Time, msquared and 2 others like this.
  4. Jedi

    Jedi Moderator
    Moderator Lifetime Rossa Owner

    Mar 18, 2008
    31,529
    Seattle Area
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    Dave
    You never cease to amaze me in some of the stuff you know, Yin. :)

    Jedi
     
  5. mchas

    mchas F1 Veteran
    Silver Subscribed

    Oct 5, 2004
    5,903
    Los Angeles
    Full Name:
    Mark
    Do you live on Jupiter by any chance? :)
     
  6. WPOZZZ

    WPOZZZ F1 Veteran

    Aug 22, 2012
    6,477
    Honolulu, HI
    Damn! The knowledge here is amazing.
     
  7. drgek

    drgek Formula 3

    Jun 21, 2004
    1,142
    Full Name:
    Gary
    Great explanation. It doesn't have a day or date, just a power reserve.
     
  8. definitelysomeday

    definitelysomeday Formula Junior

    Aug 7, 2009
    655
    Ft. Lauderdale
    Full Name:
    Tom Kavan
    Like the Patek 5015???
     
  9. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
    3,079
    SanFrancisco BayArea
    Full Name:
    1983 US 308 GTS QV
    Glad you are returning it for service; the only way to get the problem addressed.

    Maybe its a "collectors item" as-is because of the factory flaw!

    For lesser watches, such a bizarre flaw would incriminate it as a fake.
     

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