1675 accuracy survey

[shedlock2000]

Originally Posted by Tools

COSC is not criteria wherein which a watch should run, even though that seems to be Internet Lore. Additionally, COSC did not even exist prior to 1974 when it was standardized as the Swiss Chronometer testing organization.

-4/+6 is the 10 second swing that a watch under stress testing can swing in order to pass the COSC criteria.

I would be happy if a pre-1974 watch ran within 5 seconds. If it did not I might ask the watchmaker to regulate as best he can for me.

Hi Larry! Thanks for weighing in!

I know COSC isn’t a criteria, but it’s a nice benchmark to try and achieve in a watch’s running.

As you can see, since the service of my 1675 it performs a lot worse than it used to. What I was curious about is what level of difference was acceptable (a question you also answered).

Because older watches have varying degrees of wear, I was curious what was an acceptable accuracy level — it seems that similar vintage watches can run very close to COSC (even at many years old). That mine is consistently out by nearly 8spd, I’m assuming that it can be adjusted to be less out (something I wouldn’t say if the deviation was significant).

Btw, do you happen to know what existed before COSC and what benchmark permitted Rolex to adorn their dials with SCOC prior to ‘74?


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[Dan S]

Average timekeeping on the wrist over the course of 24 hours is a fairly arbitrary measurement, and not necessarily indicative of the condition of the movement. Saying that a watch is +5s/day, -8s/day, +1s/day, etc. is basically meaningless, IMO. A large daily deviation after a service could indicate that the movement is not in good shape (e.g. damaged parts were not repaired/replaced), or it could just mean that the watchmaker didn't put a lot of effort into regulation.

If you measure timekeeping in 6 positions, amplitude, beat rate (both fully wound and after 24 hours), maybe one could start to get a sense of the condition of the movement. Of course, careful inspection of parts under a microscope would really be the best way to know. However, if positional variation is small, amplitude is high, isochronism is good, etc., then it's likely that your watch could be regulated to keep accurate time on your wrist with a little trial and error (and a judicious choice of overnight storage position). If it is important to you, it would be best to have a local watchmaker to help with this, or to learn how to do it yourself.

Personally, these little deviations really don't matter to me.

[flyinghell34]

After reading the few post here I thought I would give leaving the watch crown up over night along with daily wear and see the results. After 1 week the watch appears to be running +2 seconds a day.

[springer]

I recently had this 1972 GMT serviced a few months ago and it was running +1. I checked it the other day before it took off for a new home and it is stick clocking in at +1.

[00Seven]

Originally Posted by springer

I recently had this 1972 GMT serviced a few months ago and it was running +1. I checked it the other day before it took off for a new home and it is stick clocking in at +1.

Hi John! Hope all is well. Service dial and hands on my 1675 I posted above came from you. Cheers!

[Tools]

Originally Posted by shedlock2000

Hi Larry! Thanks for weighing in!

I know COSC isn’t a criteria, but it’s a nice benchmark to try and achieve in a watch’s running.

As you can see, since the service of my 1675 it performs a lot worse than it used to. What I was curious about is what level of difference was acceptable (a question you also answered).

Because older watches have varying degrees of wear, I was curious what was an acceptable accuracy level — it seems that similar vintage watches can run very close to COSC (even at many years old). That mine is consistently out by nearly 8spd, I’m assuming that it can be adjusted to be less out (something I wouldn’t say if the deviation was significant).

Btw, do you happen to know what existed before COSC and what benchmark permitted Rolex to adorn their dials with SCOC prior to ‘74?


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Before the Swiss industry standardized and developed COSC, anybody could put Chronometer on the dial. Now, for Swiss watches, they must be submitted to COSC. Japan, Germany, etc., watch makers have their own testing systems and criteria which are similar.

Rolex did enter into Kew accuracy testing "competitions" in order to claim accuracy records and a valid history. Every watch didn't get tested, just enough to make some marketing claims.

It was only a few years ago that Rolex actually defined their "Superlative" nomenclature and didn't really advertise any particular accuracy standards beforehand.

[Seddyspaghetti]

Mine’s about +2 a day


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[jedione65]

Originally Posted by shedlock2000

Hi Larry! Thanks for weighing in!

I know COSC isn’t a criteria, but it’s a nice benchmark to try and achieve in a watch’s running.

As you can see, since the service of my 1675 it performs a lot worse than it used to. What I was curious about is what level of difference was acceptable (a question you also answered).

Because older watches have varying degrees of wear, I was curious what was an acceptable accuracy level — it seems that similar vintage watches can run very close to COSC (even at many years old). That mine is consistently out by nearly 8spd, I’m assuming that it can be adjusted to be less out (something I wouldn’t say if the deviation was significant).


Btw, do you happen to know what existed before COSC and what benchmark permitted Rolex to adorn their dials with SCOC prior to ‘74?


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I see I’m not the only one using WatchTracker. A great app. But depending on how long you had it serviced you could try taking it to a watchmaker, some can regulate it on the spot. At the very least they will look at the movement and check the amplitude and will tell you if it needs a service (if they’re good and honest).

[springer]

Originally Posted by 00Seven

Hi John! Hope all is well. Service dial and hands on my 1675 I posted above came from you. Cheers!

It still looks great Nick. It's nice to see a happy ending on some of these vintage GMTs - whether it's a functional restoration or original restoration.

Take care and glad to see you're still enjoying the watch.

jP

[shedlock2000]

Originally Posted by Dan S

Average timekeeping on the wrist over the course of 24 hours is a fairly arbitrary measurement, and not necessarily indicative of the condition of the movement. Saying that a watch is +5s/day, -8s/day, +1s/day, etc. is basically meaningless, IMO. A large daily deviation after a service could indicate that the movement is not in good shape (e.g. damaged parts were not repaired/replaced), or it could just mean that the watchmaker didn't put a lot of effort into regulation.

If you measure timekeeping in 6 positions, amplitude, beat rate (both fully wound and after 24 hours), maybe one could start to get a sense of the condition of the movement. Of course, careful inspection of parts under a microscope would really be the best way to know. However, if positional variation is small, amplitude is high, isochronism is good, etc., then it's likely that your watch could be regulated to keep accurate time on your wrist with a little trial and error (and a judicious choice of overnight storage position). If it is important to you, it would be best to have a local watchmaker to help with this, or to learn how to do it yourself.

Personally, these little deviations really don't matter to me.

I understand what you’re saying, but I don’t ever take my watch off, so what matters to me is the daily performance (not whether or not I can gain a few seconds over night by leaving it crown up).

The watch had a full RSC restoration conducted 6 months ago (not worn since until now). New crystal, dial, bezel, bezel insert, handset, bracelet, crown, tube, most of the wheels — and a bunch of other things as well looking at the movement which appears pretty-much like new under a loupe (while I know this is the antithesis of what is preferred here, it’s actually exactly what I *am* looking for).

I agree regarding the positional variance, but what matters to me is the overall performance (that there is little deviation between night and day intimates that the positional variance isn’t likely to be far out anyway). My AD (an RSC watchmaker) suggests that the watch needs to ‘bed-in’ for a month, but I suspect that’s the ‘dark-drawer’ repair method rather than a justifiable response. The difficulty in returning it to RSC for adjustment is now that Toronto no-longer works on 15xx movements.

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[shedlock2000]

Originally Posted by Tools

Before the Swiss industry standardized and developed COSC, anybody could put Chronometer on the dial. Now, for Swiss watches, they must be submitted to COSC. Japan, Germany, etc., watch makers have their own testing systems and criteria which are similar.

Rolex did enter into Kew accuracy testing "competitions" in order to claim accuracy records and a valid history. Every watch didn't get tested, just enough to make some marketing claims.

It was only a few years ago that Rolex actually defined their "Superlative" nomenclature and didn't really advertise any particular accuracy standards beforehand.

Ahhh! That’s interesting. So what you’re saying is that before ‘74 Rolex watches were not -4/+6 from the factory?


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[shedlock2000]

Originally Posted by Seddyspaghetti

Mine’s about +2 a day


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That’s sweet — pretty much as good as it gets! (I do like a black bezel too — my last one was a black bezel).




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[Tools]

Originally Posted by shedlock2000

Ahhh! That’s interesting. So what you’re saying is that before ‘74 Rolex watches were not -4/+6 from the factory?

They were never -4/+6 from the factory, this is a COSC construct for testing. COSC is independent and not a part of Rolex.

Movements are sent to COSC without dials or hands, and COSC tests the movement alone for 2 weeks under various environmental conditions. COSC looks for any variance outside -4/+6 seconds during testing as pass/fail criteria.

After testing the movements are sent back. Rolex then prepares them for casing, including a Clean, Oil, Adjust service and regulates them to Rolex Criteria. I have heard that the criteria was -1/+5 prior to the latest declaration that they will now use -2/+2 out-the-door.

COSC testing and their -4/+6 test criteria has not changed. Once tested and passed, they are never tested again.

[shedlock2000]

Originally Posted by Tools

They were never -4/+6 from the factory, this is a COSC construct for testing. COSC is independent and not a part of Rolex.

Movements are sent to COSC without dials or hands, and COSC tests the movement alone for 2 weeks under various environmental conditions. COSC looks for any variance outside -4/+6 seconds during testing as pass/fail criteria.

After testing the movements are sent back. Rolex then prepares them for casing, including a Clean, Oil, Adjust service and regulates them to Rolex Criteria. I have heard that the criteria was -1/+5 prior to the latest declaration that they will now use -2/+2 out-the-door.

COSC testing and their -4/+6 test criteria has not changed. Once tested and passed, they are never tested again.

Right, but what I was seeking to determine was what level of accuracy the 1675 was sent out of the factory at; to what did Rolex originally adjust them? Did they adjust them in 5 positions back in 1970 to -1/+5, or was that only after they started to COSC certify them?

I’m assuming the ’superlative chronometer’ meant something in terms of accuracy — but what exactly?


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[TimeLord2]

Originally Posted by shedlock2000

Right, but what I was seeking to determine was what level of accuracy the 1675 was sent out of the factory at; to what did Rolex originally adjust them? Did they adjust them in 5 positions back in 1970 to -1/+5, or was that only after they started to COSC certify them?

I’m assuming the ’superlative chronometer’ meant something in terms of accuracy — but what exactly?


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"Superlative Chronometer" = "Magnificent Marketing" lingo.

[shedlock2000]

Originally Posted by TimeLord2

"Superlative Chronometer" = "Magnificent Marketing" lingo.

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