# Accuracy



## watchvet (Apr 22, 2005)

Question for Roy:

How accurate (over 24 hours) are you able to set your ETA or Unitas automatic movements?

Thanks


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## Griff (Feb 23, 2003)

watchvet said:


> Question for Roy:
> 
> How accurate (over 24 hours) are you able to set your ETA or Unitas automatic movements?
> 
> ...


I would predict 1 to 3 s per day depending on the watch's particular positional errors.

I have managed through trial and error 1 s + per day on 3 of mine, but Roy will have his electronic watch timer to get it right 1st time.

Am I correct Roy?


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## MartinAtton (Mar 14, 2005)

watchvet said:


> Question for Roy:
> 
> How accurate (over 24 hours) are you able to set your ETA or Unitas automatic movements?
> 
> ...


I would agree with Griff. All 6 of my watches kep time well within chronometer tolerance: +6 -4 seconds a day, but I know their positional anomalies. My Zeno Army Diver, ETA 2846 movement, will be to within 3 or 4 seconds of the right time after a weeks wear, but only becuase I leave it face up or wear it for prescribed amounts of time. It actually suffers quite serious positional errors. It gains about 8 seconds a day face up and loses about 5 seconds a day on my wrist. My two Seikos and two ETA 2824 watches are a lot more consistent, but after a week are no closer to the correct time than my Zeno. I think that they would have a good chance of getting a COSC certificate if tested in the different temperatures and positions required. However as I know their vagaries so well I can keep them all pretty well spot on over time without setting them. You can regulate most watches with positional errors in such a way that they stays pretty close over time. Most watches when regulated as well as possible tend to gain in a face up position but lose slightly in a wear cycle. These are my observations from limited experience. Roy will no doubt be able to elaborate.

Cheers,

Martin


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## rhaythorne (Jan 12, 2004)

After around 4 days of wear and 4 nights of being left face-up on my bedside table my new RLT automatic diver (with ETA 2824-2 movement) is just 0.25 seconds slow


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## MartinAtton (Mar 14, 2005)

Sixteen years ago I paid Â£335 for a Tudor Oyster Prince. I eventually sold it last year. It kept to within a couple of seconds a day for most of the time I owned it and I used to regulate it myself after having it serviced by a local jeweller. Over the past couple of years I have acquired a Zeno Diver, Seiko Orange Monster, Seiko 5 Superior, Glycine Combat, Glycine Incursore, And Vostok Komandirskie. I thought that when I bought my overpriced Tuudor all those years ago, that it would knock spots off cheaper watches in terms of accuracy. I have discovered since, that there seems to be NO correlation between price and accuracy. All of my watches, except for the Zeno are at least as accurate as my old Tudor in terms of positional errors after regulation. Every one will keep time to less than 2 seconds a day in ANY wear cycle, apart from the Zeno which can be kept on the ball by careful wear, rest cycles of use. There also seems to be no link between movement rate and accuracy either. The Vostok does seem to be more affected by riding a bicycle for long periods of time as the frequency of the cycle vibrations seem to speed the watch up. But then at 19,800bph I suppose it is more likely to be affected than watches running at 28,800bph.

Martin


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## Roy (Feb 23, 2003)

watchvet said:


> Question for Roy:
> 
> How accurate (over 24 hours) are you able to set your ETA or Unitas automatic movements?
> 
> ...


Within 5 seconds a day.


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## MartinAtton (Mar 14, 2005)

Roy said:


> watchvet said:
> 
> 
> > Question for Roy:
> ...


I have detailed charts detailing the timekeeping vagaries of all my watches, which is why I have included the Smilies below!!!

Cheers,

Martin


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## king2b (Apr 6, 2005)

I don't understand this.

Forgive me for being ignorant, but if it is possible to adjust a watch so that it consistently gains five seconds, why cant it be adjust so as to gain none.


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## Roy (Feb 23, 2003)

I can adjust a watch +/- 0 seconds a day on the bench because it is static and the amount of power in the mainspring can be kept at the same level every day.

However when a watch is worn there are so many other factors to consider.

Temperature can make small changes.

A watch may gain or loose slightly on different people because of their different lifestyles.

Positional deviation etc.


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## AlexR (May 11, 2003)

She could be asking you to remove it,so she can look at your watch,so she can time you


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## Stan (Aug 7, 2003)

That would be Renis time not GMT then?


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## AlexR (May 11, 2003)




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## marius (Mar 11, 2005)

Roy said:


> I can adjust a watch +/- 0 seconds a day on the bench because it is static and the amount of power in the mainspring can be kept at the same level every day.
> 
> However when a watch is worn there are so many other factors to consider.
> 
> ...


Hi Roy. Did I understand the whole accuracy thing correctly then? You can set the mechanical watch to loose OR gain a few secconds every day, and it is NOT consistently losing or consistently gaining. This is why a well adjusted mechanical watch which is worn every day, will almost always outperform a quartz watch over very long periods, such as maybe 12 months, or 18 months, since the quartz watch wil CONSISTENTLY loose or CONSISTENTLY gain, even if it is only fractions of a second per day.

Or did I get it completely wrong?


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## marius (Mar 11, 2005)

MartinAtton said:


> Sixteen years ago I paid Â£335 for a Tudor Oyster Prince. I eventually sold it last year. It kept to within a couple of seconds a day for most of the time I owned it and I used to regulate it myself after having it serviced by a local jeweller. Over the past couple of years I have acquired a Zeno Diver, Seiko Orange Monster, Seiko 5 Superior, Glycine Combat, Glycine Incursore, And Vostok Komandirskie. I thought that when I bought my overpriced Tuudor all those years ago, that it would knock spots off cheaper watches in terms of accuracy. I have discovered since, that there seems to be NO correlation between price and accuracy. All of my watches, except for the Zeno are at least as accurate as my old Tudor in terms of positional errors after regulation. Every one will keep time to less than 2 seconds a day in ANY wear cycle, apart from the Zeno which can be kept on the ball by careful wear, rest cycles of use. There also seems to be no link between movement rate and accuracy either. The Vostok does seem to be more affected by riding a bicycle for long periods of time as the frequency of the cycle vibrations seem to speed the watch up. But then at 19,800bph I suppose it is more likely to be affected than watches running at 28,800bph.
> 
> Martin
> 
> ...


Maybe this is for Roy too. Could the 19800 bph ever be as accurate as 28800 bph?

One takes a complete 8 beats per second, while the other takes 5 and a half beats per second. On the face of it, it seems the faster beating one can miss a beat and not lose as much time as a slower beater missing a beat. Or is is it just easier to "mark" a full 8 beats, rather than "mark" 5,5 beats? Next question, if you have a movement that runs at 5,5 beats per second, how tough is it to modify this to 11 beats per second? Can't you just "double up" on the "teeth" on a sprocket or two?

Marius


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## MartinAtton (Mar 14, 2005)

king2b said:


> I don't understand this.
> 
> Forgive me for being ignorant, but if it is possible to adjust a watch so that it consistently gains five seconds, why cant it be adjust so as to gain none.
> 
> ...


As Roy says, the watch can be adjusted to be spot on in a particular position, but altering the temperature and position of the watch will alter its rate, as will subjecting it to vibrations of certain frequencies. Although the balance wheel of a watch is made to very fine tolerances it is not perfect. The gravitional forces acting upon it will be coming from different directions depending on the position of the watch. This can slow down or speed up the watch depending on several factors. Infinitesimal eccentricity or uneven weight distribution in the mass of material in the balance wheel will alter the motion of the escapement according to where the gravitiational pull is acting most striongly or weakly relative to the balance wheel itself.

The balance wheel runs on two bearings top and bottom and the position of the watch will affect the distribution of mass resting on the respective bearing surfaces. One may take most of the weight in one position, whereas it may be spread evenly in others.

Also, vibration or shaking movement of the watch may be close enough to the frequency of the watches escapement to speed it up or slow it down.

The tenmperature of the movement will also affect the watch, because all of the metal components will expand or shrink a minute amount with temperature change thereby affecting their size, which will in turn affect their rate of motion. A larger diameter balance wheel will swing backwards and forwards more slowly than a smaller one.

I also imagine that large temperature changes will alter the viscosity of the wtach lubricant which will in turn affect its frictional coefficient. This will then alter the watches rate.

I think this is all true, but it is only what I have gleaned through reading and using my common sense.

Cheers,

Martin


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## pg tips (May 16, 2003)

as above it's all an average with mechanicals.

for eg I have one watch that on the wrist losses 5 secs during wearing but then gains 5 seconds overnight if left dial down

I have another that gains whilst wearing but left crown up losses and so evens itself out.

I find the fun in most mechanicals is the time spent working out these variancies.


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## king2b (Apr 6, 2005)




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## rhaythorne (Jan 12, 2004)

> What ia a positional error.
> 
> (Apart from what what my Wife constantly screams at me)












It's the way a watch may run a little faster or slower, depending on whether it's lying face up, face down, crown up, crown down, 12 O'Clock high or 6 O'Clock high.


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## marius (Mar 11, 2005)

rhaythorne said:


> > What ia a positional error.
> >
> > (Apart from what what my Wife constantly screams at me)
> 
> ...


In that vein, how much should it affect the price of a watch "normally" if it is "adjusted", or "adjusted 5 positions"? Does it make the watch more "accurate", or just more consistent? Does it make a difference at all whether it was adjusted in 2 positions or 5 positions? What does this adjustment actually mean? Are there different adjustments to made to compensate for inacuracy when the watch is lying flat, for instance, than adjustments that would be made for inacuracies when the watch is 'crown up'? Does a 5 position adjustment mean only that the single adjustment capability of the watch has been used to adjust the watch to get the best average for 5 positions. Can you set it "more wrong" in the horizontal position to make up for deviance in the vertical position? Or do you actually adjust something different for horizontal inacuracy than for vertical inacuracy?

Now I shall keep quiet and listen..


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## rhaythorne (Jan 12, 2004)

marius said:



> In that vein, how much should it affect the price of a watch "normally" if it is "adjusted", or "adjusted 5 positions"? Does it make the watch more "accurate", or just more consistent? Does it make a difference at all whether it was adjusted in 2 positions or 5 positions? What does this adjustment actually mean? Are there different adjustments to made to compensate for inacuracy when the watch is lying flat, for instance, than adjustments that would be made for inacuracies when the watch is 'crown up'? Does a 5 position adjustment mean only that the single adjustment capability of the watch has been used to adjust the watch to get the best average for 5 positions. Can you set it "more wrong" in the horizontal position to make up for deviance in the vertical position? Or do you actually adjust something different for horizontal inacuracy than for vertical inacuracy?


I doubt there's a definitive answer. It all depends on the particular watch.

I don't bother too much accuracy to be honest as long as it's within, say, a couple of minutes or so per week. It seems to me that modern production techniques are far better than they used to be and so even a relativley cheap movement is now capable of performing well within chronometer specs. I would guess that, several decades ago, a watch "adjusted to 5 positions" would have been more accurate, consistent and expensive than one that was "unadjusted".

Roy might be able to provide a better answer


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## Roy (Feb 23, 2003)

The adjustments are positional and sometimes temperature.


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## ESL (Jan 27, 2004)

I hope this adds and does not distract from a very interesting thread; but I always understood that if a movement was "adjusted" to COSC standards, there are always three basic adjustments, which are:

*average daily rate* - adjusted by the regulator,

*temperature* - normally by use of a temperature compensated balance, and

*isochronism* - the ability of the watch to run at the same rate irrespective of the power reserve in the main spring.

The other "adjustments" are the traditional six, i.e. dial up/down, crown up/down/@6/@9. As far as I understand, these are normally compensated for by ensuring that the balance wheel is correctly "poised" and by other adjustments (in the escapement ?). Balance poise being one of the most critical.

To further clarify/confuse, I was always led to believe (for a COSC movement anyway) that if the movement was stated to be adjusted in three positions, it might actually mean just the three basic adjustments (as above), OR the three basic positions, PLUS three from the remaining positional adjustments, making 6 in total.









I also am led to understand that if a watch is said to be adjusted to 6 positions, it is always taken to mean 9 (3 basic and 6 positional)
















Of the 6 positional adjustments, I understand that the most important (for the majority of watches with the winder at the 3 o'clock position) is the crown down position. This is because "most" right-handed people would wear a wristwatch on their left hand, and therefore, the watch spends a significant amount of its wearing time crown down. I think the next significant position is face up, again simply because when not worn, most watches will be left in this position.

Of course, I'm no expert and most of the above could be a load of old spherical objects







. But I am always interested to find out if anyone wishes to correct me.









To finish off the answer for Martin about price corresponding to accuracy: there is generally no correleation. If you want accuracy, you could by any cheap quartz. More bucks gets you a prestigious brand name, better engineering, the use of precious materials in construction and, generally, a reliable and dependable aftersales service.

On the accuracy issue: If the quartz watch is say 1 second per week fast, it can generally be relied upon to be very accurately 1 second per week fast. to the extent that you could predict with a good degree of "accuracy" that after two months, it would have gained 8 seconds. But this is not the case with a mechanical. As has been said in previous posts, it's daily rate could be -4 and +6 for a COSC certified chronometer. On the face of it, that seems a good deal less "accurate". But in fact with all of the small daily losses and gains (-1 here, +1 there) you might find that after two months of wear, you might have only lost or gained say 2 seconds overall. So in fact - your "less accurate" watch, is actually more accurate!









So there you have it: for absolute accuracy and predictability - buy quartz. For enjoyment of ownership, and many hours discussing the pros and cons of this, that, or the other, brand of watch - get a mechanical!


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## marius (Mar 11, 2005)

Very interesting issues. Thank you. Am I correct that once the watch is built, the hardware is there, you can only adjust one thing. You cannot really do anything any more about temperature compensation, or spring tension. You have only one little adjusting lever. You can spend time adjusting that little lever until you have a "b*lls-on-accurate" watch in one specific orientation. Then you know, if you touch that little lever again, the accuracy in that specific orientation is all out again. So try to find a spot where you have the "most accuracy in the most orientations". There is no adjustment for the horizontal position, and another for crown up, and another little lever for crown down. You have one adjustment, and it affects the accuracy in all orientations? So, a watch that has been adjusted in 5 positions is very likely to never be accurate when you leave it one specific position on a bench?

( I am happy with the accuracy of my mechanical watches, I was just wondering what does it exactly mean when when a watch is upposed to adjusted in 5 positions. Sounds like it is a bit of a compromise setting, fairly good mileage and fairly good acceleration, but not both..)


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## ESL (Jan 27, 2004)

I think you are more or less correct Marius, once built, there is really only one adjustment you can make. There are perhaps a few more "tweaks" here and there that a qualified watchmaker might make, but whether they might be worth the effort, is a moot point.

The little lever you refer to - the regulator - can only really be used to adjust the watch's "average daily rate", or, how much the watch will gain or lose in any specific time period, for any given watch position. So for example: if you "regulated" the watch to gain/lose precisely 0 seconds in 24 hours whilst face down, you may find that the watch gains 2 seconds per 24 hours when crown down, loses one second per 24 when crown up, gains one second when crown right, etc.

So the general idea when a watch is regulated by the manufacturer, is the regulator would be adjusted so that the "average daily rate" or, the average of say 6 positions, is within certain standards. For COSC, this is normally stated as -4 and +6 seconds per day (for all positions, hot, cold and isochronism). As Roy (I think) stated earlier, this is only an average though. Any particular watch, may run differently when worn by a different person, due to their wearing patterns and the environment where the watch is worn. But what better quality movements give you is, in a way, greater immunity to these variations.

When you say _"So, a watch that has been adjusted in 5 positions is very likely to never be accurate when you leave it one specific position on a bench?"_ Thats not strictly true and depends on your definition of "accurate" For example: if you were to regulate your watch to be "spot on" when left face down, it may for example gain 1 second per day when left face up. This does not make the movement "inaccurate", as the watch is likely to always gain exactly 1 second when left face up. So actually, the watch is accurate, because you can always predict that it would gain 1 sec a day when left in this position.

We all do (occasionally







) but we all shouldn't, get hung up on the accuracy of our mechanicals. As I said earlier, typically the variations in the daily wearing rate of mechanical watches will tend to cancel each other out over time, even more so if we understand our watches performance in certain positions. So that you actually find that over time, your mechanical watch can actually end up closer to the "set" time say, six months later, that a quartz watch would.


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## marius (Mar 11, 2005)

ESL said:


> I think you are more or less correct Marius, once built, there is really only one adjustment you can make. There are perhaps a few more "tweaks" here and there that a qualified watchmaker might make, but whether they might be worth the effort, is a moot point.
> 
> The little lever you refer to - the regulator - can only really be used to adjust the watch's "average daily rate", or, how much the watch will gain or lose in any specific time period, for any given watch position. So for example: if you "regulated" the watch to gain/lose precisely 0 seconds in 24 hours whilst face down, you may find that the watch gains 2 seconds per 24 hours when crown down, loses one second per 24 when crown up, gains one second when crown right, etc.
> 
> ...


This is really interesting stuff. (not a single Renis joke unfortunately) You touched on abother issue there. What really is the difference between "adjusted" and "regulated". "Regulating", you can do by messing with the little "regulator", but "adjusting" is something that can possibly be done by a real watchmaker?

Like taking a screwdriver and a colortune kit to to your car, and "regulating" the air-fuel mixture, but taking it into a proper machine shop to "blueprint" and balance the engine?

Thank you for the information.


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## ESL (Jan 27, 2004)

Well, to continue the engine analogy it's a bit like this.

The "regulator" is a bit like the throttle, in that what is does is alter the amount of fuel delivered into the engine: vary the amount of fuel, and the engine speed will vary. The watch regulator works similarly, in that it regulates how the power from the main spring is delivered to the movement, making it work faster or slower.

The "adjustements" related to a car engine, might be to bore out the pipe and ductwork to gas-flow the exhaust ports and inlet ports. To add devices to measure air density, humidity and temperature, which will in turn affect the fuel-air mix to give more accuracy in the amounts of fuel required to maintain a given power output with variations in temperature. Engine Management Systems are used to monitor the power delivery, etc.

In a watch, the adjustments may be to the way the balance spring is mounted, and how accurately the balance is "poised". Some balance wheels on "quality" movements, have screws in them. These are initially used to "balance" the balance wheel, or "poise" it. But then some are also used for temperature compensation.

But like the car, unless you really know what you are doing, ALL of these things are best left *completely *alone. On a watch movement unlike a car, you can't generally just "tweak" it a bit here and there and see what happens. Most of the time, it takes very specialised measuring equipment to even see what change has actually been made.

I don't pretend in any way to be an expert on any of this - just a general interest in things horological, but I have learned enough, to leave most of it alone.


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## marius (Mar 11, 2005)

Ok, one more shot at this:

The regulator is the hand-throttle on a tractor, once you set it, it is like a tortoise without legs. It stays exactly where you left it. If you have nothig better to do, you can mess with it a bit untill you find a spot where you like the speed. This is "regulating".

Adjustment is an attempt to improve on the inherent ability of the watch to stay consistently at the speed at which you left the regulator. This could possibly be done by a real watchmaker, if the quality of the watch allows it. He could improve on the balance for instance. Nothing you can do with a needle file in front of the TV.

The reason for all of these questions is not that I want to try to do any of these things. I am trying to get a better understanding of what it means when someone says a watch is really really expensive, because it has been "regulated" or adjusted. In reality, you can REGULATE in any number of positions, but ADJUSTMENT is done or it is not done? Is this about the gist of it?


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## ESL (Jan 27, 2004)

You have hit the nail on the head.

Anyone with a bit of knowledge, time and patience, can regulate any watch to a reasonable degree. But this won't make a watch run more consistently from day to day, it doesn't change how the watch keeps time at different temperatures, nor how well it keeps time when it is being bounced around as you walk. This needs "adjustments" which are generally made during design and manufacture.

However a skilled watchmaker can take an unadjusted watch and, with enough time and effort, make adjustments so that it keeps excellent time.

On the other hand, a skilled watchmaker can also take a block of brass and, with enough time and effort, make a watch out of it that keeps excellent time.









In general, it will take a lot less effort to make an "adjusted" watch keep good time because the watch was made right to begin with.


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## Mrcrowley (Apr 23, 2003)

Whilst on the subject of accuracy...........

My Spitfire is averaging +0.5 sec a day. Not bad for a non chronometer rated watch?


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## ESL (Jan 27, 2004)

I love IWC's, and Spitfire's are one of my faves.

But it also serves to illustrate what I said:



> In general, it will take a lot less effort to make an "adjusted" watch keep good time because the watch was made right to begin with.


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## marius (Mar 11, 2005)

Thanks again for the interesting discussion. I know Harley riders, and and a few car fundi's who specifically like to buy real basic bikes and cars, because these can be stripped down and changed and modified into what they really want. If they buy engines, it is never a "tweaked" engine, rather a very basic one, which they can "tweak" themselves. I understand that this requires, apart from the skill, also a very specific "mentality' (for lack of a better word). I wonder if there are watch lovers like this. Very skilled people who would prefer an "unadjusted" watch, just because they can "make it run better than the original factory issue".

Thanks again. I really appreciate the interesting information.

Marius.


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## Griff (Feb 23, 2003)

A Seiko 5 can run as accurately as any mech. watch, including an IWC


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## marius (Mar 11, 2005)

Griff said:


> A Seiko 5 can run as accurately as any mech. watch, including an IWC
> 
> 
> 
> ...


I absolutely agree. My most accurate watch is a 9 year old Seiko 5.

Wear it a lot, every morning it is within 7 seconds off the radio time signal.


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