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4 March 2019, 03:27 AM | #1 |
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Cosc
Was wondering... with COSC being -4/+6, why is running faster at +6 a greater margin of accuracy when compared to running slower?
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4 March 2019, 04:58 AM | #2 |
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The bias towards gaining is largely based on watch wearers being more tolerant towards a watch gaining over losing.
The target range there is 10s and that is the ‘real’ characteristic of a chronometer - isochronism within 10s. The average rate -4+6 is often quoted but is it really the impressive number. A watch with a delta of 100 could still be regulated to average out at +-0, but would in no way be meeting chronometer specs. Hope that helps and I’ve not made it more confusing. |
4 March 2019, 09:46 AM | #3 | |
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COSC is a torture test, and during one phase, the movement must stay within a 10 second swing of -4/+6 from a set base time in order to pass the test. Too many think that "within COSC" means that if your watch runs at +6 daily it is "within", but that is way too simplistic.
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8 March 2019, 01:48 PM | #4 |
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Imagine it's just a preferential bias to have the watch run a little fast overall. Hacking the second hand to reset is a lot easier than dealing with the minute hand, then waiting on the second hand and so on.
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8 March 2019, 02:50 PM | #5 | |
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Rolex fixed that - now it’s -2/+2. They say “take that COSC” Sent from my iPhone using Tapatalk Pro
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8 March 2019, 10:05 PM | #6 |
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Even after testing on a machine to this new-2+2 spec ,its possible it could vary while on the wrist in he real world.Just like when the test car fuel consumption in a controlled environment,its doubtful if the driver will get the exact same miles per gallon.Just to many variables like traffic, how heavy foot on the gas pedal,gear changing etc, well its like that with watch movements while on the wrist.
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ICom Pro3 All posts are my own opinion and my opinion only. "The clock of life is wound but once, and no man has the power to tell just when the hands will stop. Now is the only time you actually own the time, Place no faith in time, for the clock may soon be still for ever." Good Judgement comes from experience,experience comes from Bad Judgement,.Buy quality, cry once; buy cheap, cry again and again. www.mc0yad.club Second in command CEO and left handed watch winder |
8 March 2019, 10:30 PM | #7 | |
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All true Peter. No mechanical watch in real world will perform as a cased movement on the bench. If one wants perfection, choose a quartz model. As you prolly know, I was being light-hearted in my reply. I believe there is no way for anyone to know the answer to the OP’s original question. Can you share any knowledge on the “why” of COSC limits? Many have opined on the range being 10 seconds (-4/+6). But why wasn’t it set at -5/+5? Or -6/+4? Ultimate Rolex WatchTech trivia round 2... Sent from my iPhone using Tapatalk Pro
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9 March 2019, 12:03 AM | #8 | |
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That was until watches like the Seiko Grand come on the scene and started to wipe the floor with the Swiss mechanical watch industry.Now in those days only 2 brands in the + 23 years of the competitions submitted movements of only serial production for retail sale(Seiko and GP).All others were specially made movements just for the competition test and not then for retail sale. Now Seiko first entered the competition,with other watches from all over the world,including most of the Swiss high end brands.But then for a much higher standard than today's COSC,the Astronomical Observatory Authorisation Chronometer Standard (+/- 2/3 seconds over 48 hours) Out of many watches submitted only two passed this test a Seiko Grand just a production model, and Giraud Peregaux this time a specially build for the test model.And in the late 1960s there were only two companies, who could sell watches, passed astronomical observatory authorisation Chronometer in those days,just Seiko and Giraud Peregaux.As the Japanese had dominated the tests in the very late 1960s and the two preceding events the early into the 1970s.So in 1972 many of Swiss watch manufacturers demanded the end of the observatory competitions,and it was ended in 1973,now thats when the Swiss COSC was founded but run by the Swiss but for the Swiss brands only.Because of the high volume of movements tested by Rolex at the COSC Rolex has there own machine there to test there movements and Rolex is one of the biggest payee to the Swiss COSC.
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ICom Pro3 All posts are my own opinion and my opinion only. "The clock of life is wound but once, and no man has the power to tell just when the hands will stop. Now is the only time you actually own the time, Place no faith in time, for the clock may soon be still for ever." Good Judgement comes from experience,experience comes from Bad Judgement,.Buy quality, cry once; buy cheap, cry again and again. www.mc0yad.club Second in command CEO and left handed watch winder |
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9 March 2019, 12:41 AM | #9 | |
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Yes, yes and yes... But any idea why the delegates used -4/+6? And not -5/+5 or -6/+4? Sent from my iPhone using Tapatalk Pro
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