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Speedmaster: Does positioning overnight affect the accuracy?

Prestonbarnett
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JeremyS JeremyS
Your Speedmaster sounds pretty close to mine in terms of rate. It's about a month old and runs around 8 seconds fast per day. Of course, I have no idea when it was manufactured, so who knows the "actual" age, but it was purchased new. I don't have any plans to tempt fate and have Omega or anyone else adjust it. It's operating within the manufacturer's specifications, and gaining a few seconds per day is not a problem, particularly when the seconds are displayed on a small sub-dial with hashes as 5-second intervals. Crown down seems to slow mine to around 6 seconds, but your watch might behave differently. I'm assuming you're winding the watch daily (apologies if you mentioned that and I missed it)?

Hey man I’m winding every day and to be fair I’ve only had it 2 days but I’m going to try crown down tonight to see if it slows at all. And winding fully every day between 0600 and 0700
 
M'Bob
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Wonder if this can be clarified regarding a cal 321:

The Delta for this caliber is noted above to be the difference between the fasted and slowest positions. But let’s say you eliminate the positional variable by just testing the watch in a dial-up position. You wind it fully, set it down, and measure the time at full wind, and 24 hours later. Is the position “Delta” number (20 seconds) the same as whatever slowing in the rate is acceptable by having the mainspring wind down...or are there two different Delta figures?
 
Archer
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M'Bob M'Bob
Wonder if this can be clarified regarding a cal 321:

The Delta for this caliber is noted above to be the difference between the fasted and slowest positions. But let’s say you eliminate the positional variable by just testing the watch in a dial-up position. You wind it fully, set it down, and measure the time at full wind, and 24 hours later. Is the position “Delta” number (20 seconds) the same as whatever slowing in the rate is acceptable by having the mainspring wind down...or are there two different Delta figures?

There are two Delta figures. One for full wind, and one for 24 hours after full wind.

For the 321, it's 20 seconds over 3 positions at full wind, and 30 seconds over 3 positions at 24 hours after full wind.

The fact that these are different numbers will tell you that the positions will drift as the mainspring runs down (lack of isochronism).

Note that there is no average rate tolerance at 24 hours after full wind, so the numbers of average rate are only measured at full wind.

Not sure if this answers your question, but with what I can make of it that's all I can offer at this point. If I haven't, please clarify and I'll try to answer.
 
M'Bob
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Archer Archer
Note that there is no average rate tolerance at 24 hours after full wind, so the numbers of average rate are only measured at full wind.

Thanks. The average rate tolerance is the -1 to +16 you mention earlier in the thread, yes? And, if I’m reading you correctly, for this caliber, it’s perfectly acceptable to lose ten seconds in rate from full wind to 24 hours later?
 
Archer
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M'Bob M'Bob
Thanks. The average rate tolerance is the -1 to +16 you mention earlier in the thread, yes?

Yes.

M'Bob M'Bob
And, if I’m reading you correctly, for this caliber, it’s perfectly acceptable to lose ten seconds in rate from full wind to 24 hours later?

I'm not sure what you mean by this. The Delta over 3 positions can increase by 10 seconds.
 
M'Bob
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Archer Archer
I'm not sure what you mean by this. The Delta over 3 positions can increase by 10 seconds

Yes, that’s right, I meant gain. Thanks.

So, let’s say this gain of ten seconds happens daily, but at the 24 hour mark, you fully wind the watch up again, and then it resumes its more accurate rate. At around the end of one week, though, the watch will be roughly a minute off/slow. In other words, the rate at full wind is not purposely adjusted at service a bit fast, is it, to compensate for the gain that often happens as the mainspring winds down?
Edited:
 
Archer
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M'Bob M'Bob
Yes, that’s right, I meant gain. Thanks.

A Delta increase can be gains or losses in actual rate - the Delta is only a difference is rate and is not negative or positive.

M'Bob M'Bob
So, let’s say this gain of ten seconds happens daily, but at the 24 hour mark, you fully wind the watch up again, and then it resumes its more accurate rate. At around the end of one week, though, the watch will be roughly a minute off/slow.

Keep in mind this is a Delta increase across positions, so it doesn't mean it will gain this much or lose this much in any position, only that the difference can be as much as 10 seconds larger.

M'Bob M'Bob
In other words, the rate at full wind is not purposely adjusted at service a bit fast, is it, to compensate for the gain that often happens as the mainspring winds down?

Watches do not universally gain or lose time when they run down. It depends on a number of factors whether the watch gains or loses time as the balance amplitude drops.

Omega doesn't aim for "zero" average rate - they always set a target rate that is slightly fast, because people tend to tolerate a watch that runs a few seconds fast, and not one that runs even 1 seconds slow, even the slow one is more accurate - irrational but the way it is.
 
M'Bob
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Got it. So back to my earlier question: If you fully wind the watch, don’t wear it (eliminating the effects of position), set it down dial-up, and re-check the time 24 hours later, would it be your guess that it would gain some time, maybe a few seconds or more slower?
 
Archer
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M'Bob M'Bob
Got it. So back to my earlier question: If you fully wind the watch, don’t wear it (eliminating the effects of position), set it down dial-up, and re-check the time 24 hours later, would it be your guess that it would gain some time, maybe a few seconds or more slower?

Again if it gains or loses will depend on a number of factors. For example how much the balance amplitude drops, and if the initial amplitude was already low or was quite good. It will depend on how the balance spring is set-up, how it is reacting with the regulating pins. One watch may gain, and another identical watch may lose.

The only way to know for your specific watch, is to test it.
 
M'Bob
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Archer Archer
Again if it gains or loses will depend on a number of factors. For example how much the balance amplitude drops, and if the initial amplitude was already low or was quite good. It will depend on how the balance spring is set-up, how it is reacting with the regulating pins. One watch may gain, and another identical watch may lose.

The only way to know for your specific watch, is to test it.

Great, thanks for clarifying.
 
M'Bob
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Archer Archer
Note that Omega also has tolerances at 24 hours after full wind, and there the Delta is allowed to be as much as 30 seconds. So as the mainspring winds down, they allow for the accuracy to drift. So the first example above I gave where the average is zero, now the three readings could be 0, -15, and +15.

If you take all this into consideration, you can see that there could easily be a watch that is fully within tolerances, and running very close to +30 per day. Of course if yours runs consistently +30, I would look into getting it regulated if that is a concern.

Okay, I’m probably being thick about this, and thanks in advance for your patience. But there’s one thing I’m still missing:

So the first part I think I get - the watch runs faster in one position 15 seconds, slow in another 15 seconds, so the average is zero...within the stated tolerance.

But what’s eluding me is the second part. If the watch runs consistently at +30, how is it still with the tolerances of -1 and +16 a day? Thanks.
 
Archer
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M'Bob M'Bob
Okay, I’m probably being thick about this, and thanks in advance for your patience. But there’s one thing I’m still missing:

So the first part I think I get - the watch runs faster in one position 15 seconds, slow in another 15 seconds, so the average is zero...within the stated tolerance.

But what’s eluding me is the second part. If the watch runs consistently at +30, how is it still with the tolerances of -1 and +16 a day? Thanks.

Because the average rate on that one would not be zero, but on the high end of the average tolerance range, which would mean at least one position is very fast. If it spends the majority of the day in that very fast position, it will be...very fast.
 
artek
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Sorry for the amateur question but can anyone recommend a technique, or an app (iOS) or something to best measure the accuracy? Or something that helps with this process. Thanks.
 
Lurk41
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Cheap method: (synchronized) phone/PC clock and a 24h comparison against the watch.
Pro method: a timegrapher

Phone app... do not expect too much... First you need to buy the app, then a good mic that will cost already half of the price of the timegrapher. And only the s/day figure will be okay-ish

Archer Archer
people tend to tolerate a watch that runs a few seconds fast, and not one that runs even 1 seconds slow, even the slow one is more accurate - irrational but the way it is.
That is because it is better to arrive early than late at a meeting or a date 😉
 
Archer
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Lurk41 Lurk41
That is because it is better to arrive early than late at a meeting or a date 😉

If you are cutting your arrival time to within a second, you should probably just leave earlier. 😉
 
Lurk41
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True 😁

Regarding business meetings, a watch could quickly run 2min late with a -6/+6 tolerance instead of -1/+11. Most of the people would find it perfectly fine so I guess it is not what justifies it. But for example, with the whole "Agile" way of working in the software development, even 1 or 2min are less and less tolerated. (personnally, I lose more time in useless meetings than waiting 2min at the start of each useful one)

Hopefully, most of the people working in Agile use ugly smartwatches. I must be one of the few without one... Despite all the freaky things I could hear in some meetings, I did not find it useful to monitor my heart while I am attending them 😁
 
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