Daily use and service intervals

Discussion in 'Chronometers' started by sharukh, May 4, 2018.

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  1. sharukh

    sharukh Registered User
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    Oct 10, 2011
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    This is in continuation (sort of) from another thread.

    Should a chronometer be run 24/7 ? I know they were built to be run that way and I believe the suggested service interval was three years. But these timepieces are now older with at least some wear. And most have not been serviced at optimal intervals.

    That said, what is the suggested interval between services if the chronometer is being run 24/7 ? What if it's just run say once a month ?

    And if you are not keeping the chronometer running, should it be kept full wound ? full unwound ? or somewhere in between ?

    I am basically asking what is the suggested best practice ?

    Sharukh
     
  2. glenhead

    glenhead Registered User
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    You may get a lot of opinions on this one. Any answer you get will be an opinion, and here's mine. This is based on the assumption you're talking about a wristwatch or pocket chronometer.

    Chronometers were made to be run all the time. Whether you run one all the time now depends on its condition. "Some wear" is a very relative term, ranging from barely visible with high magnification to things that are verging on worn out. If the condition is more on the pretty-good end of the spectrum, then if it was mine I'd run it all the time, just because I could.

    The old three-year service interval was based on natural lubricants that oxidize and evaporate. Modern fully-synthetic lubricants do neither - they're incredibly stable over a very long term. I use nothing but fully-synthetic lubricants in all the timepieces I work on or own. Anything in the Moebius 9000 series is fully synthetic. In a well-sealed case, where the movement is protected from water and dust and body grunge, I'd be comfortable going seven years between overhauls if it was going all the time in a watch that I'd overhauled (so I know it was done to my standards). You could shorten that to five years if you want to be really conservative. If you run it only once a month, frankly it'll probably last forever, but I'd still go with seven years just out of an overabundance of caution.

    Running it all the time will keep the lubricants distributed where they need to be. If you choose to run it only occasionally, just be sure to let it run for "a while". You want to give the lubricants time to be thoroughly redistributed. I believe there is some credence to the concern that the lubricants may migrate away from where they need to be when they sit. I don't know of any research that proves it one way or another.

    If you let it run down, let the mainspring run down. The modern alloys aren't as susceptible to being "set" as the older spring-steel springs, but if they're kept tight in one position (like with a hack mechanism or something) they'll lose a bit of resilience over time.

    If you're talking about a desk or deck chronometer, then all the above pretty well applies. If the case has air holes, then I'd err more on the five-year interval because of household dust and floating grunge; if it's sealed, then I'd go seven.

    Those are my opinions. Let's see how other's differ.

    Glen
     
  3. DeweyC

    DeweyC Registered User
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    Feb 5, 2007
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    These are good questions.

    Yes, a chronometer is designed to run 24/7 3 years. It is not designed to be started and stopped. Some M21s have an "aftermarket" (1948; Norfolk USN Instrument Shop) balance brake that makes it more convenient to start and stop a chronometer, but it should never be allowed to run down completely.

    While it is "convenient" to run an M21 w/ balance brake once a month, this is a risky proposition for anything else. Any timepiece is most at risk is when it is out of its case.

    At the end of 3 years they were sent for service. This holds true today. In the past it was because the organic oils would start to congeal. Today, it is because the modern oils volatilize. I have seen instruments that self destructed after 5 years because the center wheel seized.

    So you can see, the issue is time since last service; not usage.

    Every modern wrist watch in a sealed case still needs to be serviced every 5 years because the synthetics dry up. The brands actually take back unsold inventory and service those watches. FWIW, I think it peculiar that buyers of expensive new watches do not ask how old the lubes are. I can only imagine the anger when the watch that was in stock for 5 years requires service 6 months out of warranty.

    Chronometers are like puppies and need routine care and feeding. Deck watches are cats.

    Yes, immobilize the balance while the instrument still has power on it.

    As for winding from a dead stop; there is no foolproof method. Hamilton did change the clearances to avoid the risk of jamming, but this does not provide a guarantee.

    And btw, this applies to all chronometers.

    First, remember, these were never intended for collectors. They were intended for use in a situation where one person was held accountable to ensure they were wound each day. These were in continuous operation for 3 years at a clip and only stopped for service.

    I tell collectors to not trust life partners or hired help. If they are going away for more than 48 hours, they should lock the balance and restart upon return.

    The only thing you can do is to slowly invert the instrument and hope the balance does not rotate and result in a jam of the impulse jewel and an EW tooth. I would put a 1/4 turn of wind on it and start it by putting it 12 up and rocking from 9 to 3 gently. That way if it did jam and break a pivot you have minimal damage.

    To be absolutely certain your instrument has not broken a pivot after being fully powered down, you would remove the instrument from the case and physically check the EW and balance pivots to ensure the are intact.

    And to fully square this circle, I charge $2000 to replicate an English detent. And I do not worry about time when doing so.

    Regards,

    Dewey



     
  4. sharukh

    sharukh Registered User
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    Oct 10, 2011
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    Glen, Dewey,

    Many thanks for answering my queries.

    One more -- what oils do you use ? I used 9020 and 9010 as the pivots got finer.

    I've picked up another chronometer. This one has no box, a re-pivoted escape arbor and a detent in two pieces. But I'll start a separate thread for that.

    Thank you, have a great week ahead.

    Sharukh
     
  5. DeweyC

    DeweyC Registered User
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    HP 1000 at escapement; Esyntha at train. Just because the oil sez chron does not mean it meant navigational instruments.
     
  6. sharukh

    sharukh Registered User
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    Than you Dewey. Much appreciated.

    Sharukh.
     

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