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Moonwatch 3861 Seconds dial jumping back-forth when adjusting time counter-clock wise: normal?

  1. Califfo Sep 11, 2023

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    Hi all
    I am a very happy new holder of a Speedmaster Moonwatch 3861 with caliber 3861 and I noted that when, with the crown correctly pulled and the seconds well stopped, I adjust the hour in the counter-clockwise direction the seconds dial jumps back and forth (of 1-2sec) just at the beginning of the crown motion.
    This does not happen when the time is set / adjusted in the clockwise direction.

    Is this behaviour normal?
    Does it happen to anyone else please?
    Can it be detrimental to the mechanism in the short / long term?

    I thank you for your kind attention and help, looking forward to your kind replies

    Rgds

    Emanuele
     
  2. Canuck Sep 11, 2023

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    Completely normal.
     
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  3. Califfo Sep 11, 2023

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    Thanks a lot for your prompt and reassuring reply.

    without wanting to abuse and for my curiosity
    - what does justify this?
    - is it not better than to adjust time always clockwise then?

    thanks a lot for your attention and replies

    rgds

    Emanuele
     
  4. Canuck Sep 11, 2023

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    This phenomenon is the result of microscopic amounts of “lash”, or freedom between the gear teeth of any mechanism that uses gears. Without that bit of lash, the mechanism certainly would not operate. Watches operate using a mainspring providing power, turning the gears in one direction to power the watch. When you turn the hands backwards, often (but not always), the gears are inclined the”counter rotate” (turn backwards) a microscopic amount due to lash in the gear teeth. This can cause the seconds hand to back up a bit. I have a Speedmaster Professional with the calibre 863 movement in it. I suspect there will be a lot of negative comments as a result of my disclosing this. But when I turn the hands backwards, the watch will actually run backwards for up to 15-seconds. I have serviced watches for many decades, and turning the hands backwards will never cause a problem.
     
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  5. Califfo Sep 11, 2023

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    Thanks a lot, very interesting information I appreciate.

    Last question : this is my first professional manual watch and i have always had automatic ones. i have the omega speed master reduced and i have never noticed this behaviour on automatic watches, omega included.

    May i lastly ask if this behavior of seconds backwinding is finally occurring on manual watches only please?

    This is why this behavior drew my attention so rapidly.

    Thanks for your patient attention
    Rgds
    Emanuele
     
  6. Canuck Sep 11, 2023

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    If you will re-read my post, I stated that usually (but not always) will you see the seconds hand backing up a bit. This would apply to most mechanical watches. Some chronographs (your Speedmaster reduced for example) have a “brake” that contacts the centre sweep seconds hand drive gear. This brake will prevent the seconds hand from backing up when you set the hands. Automatic winders and manual winders (non-chronographs) don’t have the brake, so you will very often notice the seconds hand doing that. This phenomenon can appear on ANY make of watch, Omega included! And it will usually (but not always) show up on manual winders, and automatics. Rest easy. There is no problem!
     
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  7. Califfo Sep 11, 2023

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    Thanks sincerely for your patience and I apologise for my insistence.
    Cheers
     
    Edited Sep 11, 2023
  8. Canuck Sep 11, 2023

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    If the STOP button has been pressed to stop the chronograph function, the brake will have contacted the centre sweep seconds wheel. Or SHOULD have! If the chronograph has had the STOP button pressed to stop the chronograph, and the sweep seconds hand moves backwards when you set the time backwards, that warrants having the watch looked at. On the other hand, if the chronograph is operating when you set the time backwards (an unlikely occurrence), then the sweep hand could indeed move counter clockwise. You’ll only know for sure if you have the watch checked out.
     
  9. Califfo Sep 11, 2023

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    I had fully wound the watch from a stopped / unused condition
    Chrono was off
    The watch seconds hand just jerked backward / jumped back-forth to the same initial position —when setting time counter clockwise— without continuing to decrease.
    No jerk when setting the hour clockwise.
    It is a 1sec backward jerk without seconds decrease:
    -is this still normal? Has anyone else seen this please?
    -Can it be damaging in the short/long term?

    thanks a lot
     
    Edited Sep 11, 2023
  10. Canuck Sep 11, 2023

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    You said the chronograph was OFF when you found the centre sweep hand backing up. Since the chronograph was OFF, the brake should (I would think) have been applied to the centre sweep hand, preventing it from backing up. Regardless of what you may hear or be told, your mind won’t rest easy until someone checks it out. You really have nothing to worry about!
     
  11. Califfo Sep 11, 2023

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    It is not the centre sweep (i understand it as the chrono seconds needle) but the seconds hand which does not continuously move backwards but jerks backwards of an angular displacement equivalent to 1 sec. Even after several crown’s counter clockwise rotations, the seconds are in the same position but have been submitted to as many jerks as crown’s rotations.

    i fear that this can wear hammer the hacking system.

    I fully listen to your feedbacks and i thank you: i just insist as i fear that i had not been clear to explain my issue and i apologize if it is the case.

    thanks again
     
  12. Canuck Sep 11, 2023

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    Your watch has TWO seconds hands. The centre one is the chronograph seconds hand. The small one is the SUBSIDIARY seconds hand. The centre one has a brake that is applied when the chronograph is not running. The subsidiary seconds hand operates continually when the watch is running. It does NOT have a brake. Which seconds hand backs up when the hands are set backwards?
     
  13. Califfo Sep 11, 2023

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    It is the seconds (subsidiary?) which are on the small quadrant top left and which count the seconds of the day time
     
  14. Canuck Sep 12, 2023

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    Please, re-read my latest reply. The centre sweep seconds hand (the chronograph seconds hand) has a BRAKE which steadies the sweep seconds hand when the chronograph is not operating. The subsidiary seconds hand operates all the time when the watch is running, whether the chronograph hands are operating, or not. It does NOT HAVE A BRAKE! It is normal for the subsidiary seconds hand to back up a bit when the time is set counter-clockwise. I’ll repeat! It is NORMAL for the subsidiary seconds hand to move counter-clockwise when setting the time counter-clockwise! I hope this answers your question!

    To anticipate your (possible) next question. With the watch running and the chronograph operating, if the time is set back, the chronograph seconds hand may very well move backwards. That is because, with the chronograph operating, the brake is NOT stopping the centre sweep seconds hand from backing up!
     
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  15. Kwijibo Dec 21, 2023

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    It's more a question of the cannon pinion friction. sometimes wondered why you second hand doesn"t move faster than its original motion whent you set your hands forward?