A brief note about real world expectations of a COSC movement
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  1. #1
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    A brief note about real world expectations of a COSC movement

    Real world expectations of a COSC movement

    With the new 50th Anniversary SUB300 just about ready to ship, I wanted to take some time to talk about the COSC movement powering the SUB300, and what can be expected from it.
    First let me describe what COSC certification is and is not:
    The COSC certifies that the movement has been adjusted in 5 positions at 3 different temperatures to an average daily rate of −4/+6 seconds per day, under laboratory conditions.
    It is very important to understand that the regulation (adjustment) and test was carried out under laboratory conditions uncased and stationary. The COSC certification does not guarantee a long term performance or accuracy, it only certifies that the movement was capable of achieving superlative accuracy results at a given time.
    Real world conditions will affect the daily rate in countless ways. Please do not be surprised that your SUB300 may not run at the same rate listed on the COSC certificate every day. There will be fluctuations and deviations from those figures depending on the temperature fluctuations and the amount of wrist/body movement.
    We also want to assure customers that if they receive a watch that is not working properly, or at all, we will take care of it as quickly as possible. We did set aside a small number of watches for replacements.

    (1) COSC
    Switzerland’s Contrôle Officiel Suisse des Chronomètres, or COSC, is the best-known watch-certifying organization. The COSC procedure lasts 15 days. Watch companies send their movements to COSC uncased. COSC then assigns each an identification number and its employees apply a generic dial with reference points that help an optical sensor track the watch’s seconds hand. Each movement is wound mechanically (automatic movements must remain rotor-less), then given a rest period of 24 hours before testing. The optical sensor reads the time off the dial daily. This reading is logged to a server controlled by two atomic clocks, which provide a timing standard. During the first 10 days, the movement is tested in five positions, each for 48 hours: crown left, crown up, crown down, dial up and dial down. Movements are kept at a temperature of 23 degrees Cº, or 73.4 degrees Fº, during this period. If a movement has a chronograph function, it is activated on day 10 to check its effect on timekeeping. On days 11 through 13, the temperature is lowered to eight degrees Cº (46.4 degrees Fº), then returned to 23 degrees Cº, then raised to 38 degrees Cº (100.4 degrees Fº). For the last two days, the temperature is brought back down to 23 degrees Cº and the movement is returned to its original position with crown facing left.

  2. #2
    Member cuthbert's Avatar
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    Re: A brief note about real world expectations of a COSC movement

    I understood the movements were adjusted in six positions, am I wrong?

    Mine according to the certificate loses a little in all position, I've worn the watch for 24h and it appears at my wrists it loses 1.5 seconds per day, so well within specs.

    A question for DOXA: should the watch go out of specs are you available to regulate it free of charge?

    For all the Sub300 owners this might be useful:

    http://forums.timezone.com/index.php...oto=1555&rid=2
    Last edited by cuthbert; December 8th, 2016 at 11:44.
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    Re: A brief note about real world expectations of a COSC movement

    Thanks for the info Doxa!

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    Member It'sAliveJim's Avatar
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    Re: A brief note about real world expectations of a COSC movement

    I was led to this thread after mailing Doxa with a question about my new SUB300 50th. For the first four days of daily wear and keeping it in a watch box, face up, overnight, the watch gained a consistent 10 secs per day. Not within spec, hence my emailing them.

    Someone else I know has had the fortunate result of their SUB300 running at +2 over four days – that's 30 seconds per day, which is brilliant.

    I have had many COSC certified watches in my time and all ran within COSC tolerances out of the box. I'm going to give it a few weeks and I've asked Doxa if they will accept a return to have it regulated if it doesn't 'settle down'. It's quite a big selling point and price premium to have a COSC certified 2824 over a standard 2824, but I would have been happy with either as I know the 2824 is a reliable workhorse that is easily capable of stunning accuracy.

    I'll see how it goes, but so as not to be a complete downer, the watch is beautiful and is the Doxa SUB I always dreamed of

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    Re: A brief note about real world expectations of a COSC movement

    I'm not an expert or watchmaker but in my experience with ETA movements, they often settle in and slow down a bit with time. Not from -10 sec/day to +/- 0, no doubt, but I'd wear it for a few months and see how it goes. So much depends on how much testing and running in the movements have had. I've yet to see an ETA movement speed up in the first year but I've seen a few (maybe 5 of 10) slow down by a few seconds. To many, this is a myth ... just speaking from my own limited experience.
    Last edited by JohnM; December 14th, 2016 at 22:46.

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    Member cuthbert's Avatar
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    Re: A brief note about real world expectations of a COSC movement

    Quote Originally Posted by It'sAliveJim View Post
    I was led to this thread after mailing Doxa with a question about my new SUB300 50th. For the first four days of daily wear and keeping it in a watch box, face up, overnight, the watch gained a consistent 10 secs per day. Not within spec, hence my emailing them.

    Someone else I know has had the fortunate result of their SUB300 running at +2 over four days – that's 30 seconds per day, which is brilliant.

    I have had many COSC certified watches in my time and all ran within COSC tolerances out of the box. I'm going to give it a few weeks and I've asked Doxa if they will accept a return to have it regulated if it doesn't 'settle down'. It's quite a big selling point and price premium to have a COSC certified 2824 over a standard 2824, but I would have been happy with either as I know the 2824 is a reliable workhorse that is easily capable of stunning accuracy.

    I'll see how it goes, but so as not to be a complete downer, the watch is beautiful and is the Doxa SUB I always dreamed of
    A simple bump during shipping can put the watch out of regulation, hopefully Doxa will take it back and re-regulate it.

    Mine is consistent with the certificate, as also the measurements are all slightly negative.
    .

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    Re: A brief note about real world expectations of a COSC movement

    Quote Originally Posted by cuthbert View Post
    I understood the movements were adjusted in six positions, am I wrong?

    Mine according to the certificate loses a little in all position, I've worn the watch for 24h and it appears at my wrists it loses 1.5 seconds per day, so well within specs.

    A question for DOXA: should the watch go out of specs are you available to regulate it free of charge?

    For all the Sub300 owners this might be useful:

    TimeZone : TZ Classics » 1111 : Reading and Understanding a COSC Certificate
    Hi, the movement will definitely at some point of time go out of spec, and this is natural and is not something to be worried about, and it is not an issue that any watch manufacturer will cover under warranty. As the COSC institute say, the regulation process reflect the results of accuracy of a movement at a give time and under laboratory circumstances, the results will always deviate due to the nature of mechanical devices, and as long as they are within the specs of +15/-10 under constant temperatures, full charge, conditions, then there is no defect.

    The Tourbillion device that costs 10K and above was invented to eliminate the deviations due to the effect of gravity on movements, yet watch movements incorporating Tourbillions are not as accurate as quartz movements.
    Last edited by DOXA S.A.; December 16th, 2016 at 03:19.

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    Re: A brief note about real world expectations of a COSC movement

    #32 of 300 reporting. After a week of wear, about 12 hours a day, I seem to be about -1 or -2 a day. Incredibly happy with that.

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    Smile Re: A brief note about real world expectations of a COSC movement

    [QUOTE=cuthbert;36501626]A simple bump during shipping can put the watch out of regulation, hopefully Doxa will take it back and re


    The shock obsorber in the movemen in theory should be abe to take the impact endured during shipment. Just my to cents.

  11. #10
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    Re: A brief note about real world expectations of a COSC movement

    [QUOTE=mf1tym;36697186]
    Quote Originally Posted by cuthbert View Post
    A simple bump during shipping can put the watch out of regulation, hopefully Doxa will take it back and re


    The shock obsorber in the movemen in theory should be abe to take the impact endured during shipment. Just my to cents.
    The schock absorber protects the movement in the fall, but it can't avoid the movement to go slightly out of spec. If a movement without incabloc or similar device drops the balance wheel breaks and it's busted.
    .

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