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American PW Timekeeping error - isochronism error

Dave Berghold

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I've recently serviced a 16s. Waltham 16-A and the timekeeping is nearly perfect for the first 12-14 hours.....in all positions. After this point, the watch looses about 2-3 seconds and hour in any position. I'm scratching my head and wondering what could be the issue. Mainspring has been replaced when I serviced it.


Having just gotten the "Theory of Horology" for Christmas, I'm going to check it out for a possible answer, but if anyone here has a thought, please let me know.

Kind regards and happy holidays,
Dave
 

Jim Michaels

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Jan 11, 2007
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Check your regulator pins, I bet they are to far apart. When the motion is high the hairspring touches each side of the pins, when the motion falls off the hairspring most likely only touches one pin which actually increases the active length of the spring, causing it to run slow.
Jim
 

Dave Berghold

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Sounds like the culprit to me. I'll check it and let you all know. Thanks!
Dave

PS. Theory of Horology had nothing to offer on this matter or at least nothing yet. I do love the book though and would recommend it to anyone studying watch or clock making or repair. Very nicely laid out and great drawings too. Tons of great information that has previously been skimmed over by authors from the early 1900's or so.
 

fuzzuki

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Dec 11, 2001
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I disagree here.
If the watch suddenly started to gain time when balance motion was low, this is what I would look for.


But in this case he's saying that it starts to lose time as motion gets lower.

If the banking pins were too far apart and the hairspring fell on one pin more than the other. You would see the watch gain time as the motion dropped. Reason being. As motion fell, the hairspring would stay on that pin longer, making the hairspring shorter for longer periods of time.

As motion gets higher the hairspring will be in between the pins longer making the hairspring longer for longer amounts of time.
Making the watch lose time.

Here we have the opposite.

First we need to know if this is an overcoil, or flat hairspring.

Either way.

First thing that should be done is to make the regulating pins as close as possible.

If it's a flat hairspring, you must leave some space so that the spring is free to move between both.
When all power is removed from the mainspring and the balance wheel is not moving, you should see the hairspring resting exactly in the middle of both banking pins.

In both these situations the hairspring should be perfectly flat, concentric, and expand as expected. An overcoil spring should expand exactly even all the way around.
Flat hairsprings should do almot ecactly the same however it will need to expand a little more away from the pinning point.

Both kinds of hairsprings should also be exactly even when resting. The distance between all coils should be exactly the same all the way around.

And when the balance wheel is in motion, it should evenly expand without any wobble.

If it's an overcoil hairspring, you should not see any movement between the pins. The banking pins of the regulator should be almost pinching the hairspring and keeping it from moving.


After that's done check the timing again.
We'll move on from there.

If you do all of this and the watch still gains when motion is low, then in deed you may have an isochronous error.

At which point you will need to obtain a diagram of the terminal curves designed by the manufacturer, and adjust the hairspring to that diagram.

If you still have an issue, we'll talk about that later.
 
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Jim Michaels

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If your regulator pins are to far apart there is a good chance at low motion they don't even touch the pins, making the watch run Slow, as the active length of the spring is at the stud. That's just a fact. Even if it only touches one pin it would still loose time at low amplitude. This is assuming the hairspring is centered or nearly centered between the pins.
 

Ansomnia

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I find this thread quite interesting and I'm sure I can learn much from the knowledgeable posters.

I have no expertise to add to the discussion but I can suggest 3 books that will likely be helpful to Dave. The "Theory of Horology" book is very nice but covers a very broad list of topics, not all of which involve repair or service. The following 3 titles were written with only repair and service in mind.
Bench Practices for Watch and Clockmakers by H.B. Fried - very practical, extremely-well illustrated, very clear and concise text. Very inexpensive. You would be crazy not to own a copy.

The Swiss Watch Repairer's Manual by H. Jendrtzki. My 2nd edition is from 1953. Beautiful book, hardcover 8 x 10" format. Like Fried's books... very practical, extremely-well illustrated, very clear and concise text. More expensive than Fried's book but I think it is also highly recommended if you are a serious watch repairer.

Watch Adjustment by H. Jendrtzki. Very similar to the above title by the same author but this book reflects technology from the 1970s onwards. My copy is an excellent 2006 Simonin A4 format hardcopy reprint. The content is different from the other Jendritzki book but is similarly "... very practical, extremely-well illustrated, very clear and concise text". Also more expensive than the Fried book but IMO a small price to pay if you work on modern mechanical watches.
Michael
 

fuzzuki

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Dec 11, 2001
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Yes Jim. You are correct.
But in all of my 23 years of repairing watches, I have still to see a watch that has the regulator pins too far apart and the hairspring centred in the middle of them.
Every time I've seen them too far apart, it's hugging the inside pin and refuses to lift off untill at least 240 degrees motion.

But yes. If they are too far apart and the hairspring is centred, you will see it lose with low motion. But those pins would have to me miles apart.


If your regulator pins are to far apart there is a good chance at low motion they don't even touch the pins, making the watch run Slow, as the active length of the spring is at the stud. That's just a fact. Even if it only touches one pin it would still loose time at low amplitude. This is assuming the hairspring is centered or nearly centered between the pins.
 

Don Dahlberg

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Aug 31, 2000
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If your regulator pins are too far apart, you would be slower in the pendant positons than in the dial positions. The spread of the regulator pins affects the pendant positons more than the dial positions. Still, what does it cost to take a look at the hairspring when the watch is beating? See if the hairspring barely moves and bounces off both regulator pins equally. It should not spend more time against one pin over the other. Sometimes people mess with regulator pins to solve some other problem. They have created a new problem to try to cancell out the real problem, which they cannot find.

The first thing you need to do is check out the action. It should be a turn and a half at full wind. It should not drop much below 1 1/4 turns after 24 hours. You say you have removed all positional errors, but is this only at full wind or both at full wind and after 24 hours? For example, positional errors are minimal at 1 1/4 turns and reverse direction above and below this action. So if you have 1 1/4 turns at full wind, you would think you have no positional error, but as the watch ran down the positional error would appear. If this is the case, then you have not really removed the positional errors and need to true and poise the balance and true the hairspring.

Another issue is the shape of the overcoil. The shape of a good overcoil is difficult to explain in a few words. The general rule is that "to speed up the watch in the short arc, bend the overcoil closer to the balance staff and visa versa." This rule is usually accurate, but there are situations where it is opposite. A better rule that is more accurate, but harder to understand is "To speed up short amplitudes, turn the point of attachment toward you, and then true the overcoil of a right-handed spring to the right and of a left-handed spring to the left." If you are a member of NAWCC write research@nawcc.org and ask for a copy of an article by Joseph Rugole from November, 1980 in Horilogical Times. It has illustrations to go along with this rule. I shall be the person who will answer your question and because of the hollidays, it will be a while before I go into the library.

Don Dahlberg
NAWCC volunteer
 

Dave Berghold

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Well,
Thanks for all of the comments and suggestions.... Here is what has transpired. I have been emailing my customer about the comments listed here and much to my surprise, the man has pretty good dexterity (for not being a watchmaker). He emailed me the following this morning:

Well Dave I just couldn’t wait to see if separating the regulator pins would rectify the issues I’m having with the 16-A. I looked at another half dozen or so watches to make sure I wasn’t barking up the wrong tree and all of them also had the slightest space between the regulator pins and the hair spring, I also looked once again at the 16-A and there was no clearance at all. After looking at the design I could tell the only way to separate the regulator pins was to bend them. There looked like sufficient clearance for me to insert a slotted screw driver between the pins and above the hairspring (while the watch was running no less). So I did and with very little pressure I twisted the screw driver while it was between the regulator pins. By chance and on the first try, the gap I created was perfect and now looked like the other watches. (Scary, so then came the test)

And he tested the watch overnight and found that the errors in timekeeping were VASTLY improved to the point of near RR specs.. It's not often that I would recommend a customer "tweak" the regulator pins on his own, no less while the watch was running....but he did so and success goes to him!

Thanks again for all of the input here.... I would not have been able to make the corrections without seeing the watch and I feel somewhat embarrassed that I didn't notice the pins once it left my hands the first time..

Happy New Year to all!!

Dave
 

Dave Berghold

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Revisiting the same watch.....

We've found an error of timekeeping and I'm not certain where to approach the correction. I'm not well versed at correcting positional errors. Poising a balance is not too much trouble, but when it comes to the proper hairspring manipulations, I don't know where to start.

Be that as it may, there is a 4 second loss per hour with the pendant in the 10:00 position and a 4 second gain per hour in the 4:00 position. I asked my customer to try both positions and this is what he's determined.

So, the question is, what would be the first thing to look at. My guess is the balance poise. Next would be the hairspring coils, inner and overcoil. But being that the error is so constantly opposite, I would think that the balance is not perfectly poised.

Any thoughts?

Thanks,
Dave
 

Ansomnia

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... there is a 4 second loss per hour with the pendant in the 10:00 position and a 4 second gain per hour in the 4:00 position. I asked my customer to try both positions and this is what he's determined. ...

Any thoughts?

Thanks,
Dave
Dave, I apologize if my comments come across a bit naïve, but I believe "pendant at 10 o'clock" and "pendant at 4 o'clock" are not standard adjustment positions. So if they are used to describe a problem, they may complicate the diagnosis and corrections.

My understanding is that pocketwatches are adjusted (and tested) for up to 6 positions:

  1. pendant up
  2. pendant down
  3. pendant left (9 o'clock)
  4. pendant right (3 o'clock)
  5. dial up
  6. dial down
Theoretically, if watches are normally adjusted and tested in these positions, it would not be so helpful to adjust and test in other positions.

If the Waltham is adjusted to 5 or 6 positions, wouldn't it be better if your customer tested in pendant left and pendant right instead of the odd positions? OTOH, if the watch was actually not adjusted from the factory then I suppose all bets are off.


Michael
 

Dave Berghold

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I understand the issue about being adjusted to 5-6 positions. With all things being equal, I would think that the 10:00 and 4:00 positions would be about the same being adjusted to 12:00 and 6:00. So, if the situation (4 sec. per hour) showed an error on these positions, what would one do to correct them?
 

Ansomnia

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I understand the issue about being adjusted to 5-6 positions. With all things being equal, I would think that the 10:00 and 4:00 positions would be about the same being adjusted to 12:00 and 6:00. So, if the situation (4 sec. per hour) showed an error on these positions, what would one do to correct them?
Well, I would have to disagree. I think it would be more useful to find out how the watch runs in the standard pendant positions. This is assuming the Waltham watch is meant to be adjusted by design.

OTOH, if the watch was not designed as an adjusted movement then perhaps it may not make much difference to pick any position where the watch seems to be running poorly.

The reason why I say this is that in order to repair a watch I think the most straightforward approach is to restore it to factory specs. Of course, one can always try to out-do the factory but without the watch being first in factory specs the results may be less than desirable.

For example, Jendritzki mentions the point of attachment of Breguet springs can affect time-keeping based on those 4 relative pendant positions. Those positions are standard references for good reasons.


Michael
 

Dave Berghold

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Michael,
I understand where you are coming from. The watch is a 5 position adjusted Waltham. So, if all things are right, then the watch should keep time in all positions withing an error of 4-5 seconds a day or so (I'm not sure what the factory specs might have been). So don't you think that an error of 4 seconds and hour is a little excessive (even though these positions are not part of the original 5)?
Dave
 

Ansomnia

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Dave, I think your concerns are justified based on those timekeeping errors. However, are you certain the errors are maximum at 1000 and 0400? Has the owner checked all the other positions and recorded the timings?

Can you post a very detailed photo of the movement showing the escapement and the pendant location?


Michael
 

Don Dahlberg

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You adjust a watch in a specific order to make sure that it is functioning correctly. First you make sure it is giving the same rate (within 5 seconds) dial up and dial down. This makes sure the the pivots and jewels are OK, (as well as abut 20 other sources of error are absent). Then you wind the watch to about 1 1/4 turns and check the pendant positons. There is no positional error from an out of poise balance or hairspring at this action. If you have a problem, it is something other than poise (another potential dozen sources of error). Now you wind the watch full and check the four pendant positions. You adjust the balance and hairspring until the watch meets specs. On a railroad grade watch, this might be within 10 seconds over the three top pendant positions. On a low grade watch, this may be more like 30-40 seconds per day over these positions. The main position for a pocket watch is pendant up. The main position for a wristwatch is pendant down. The opposite positon is the 6th position. It is always off more than the others. This is because of the direction of the inner pinning point of the hairspring. When a watch is held with the major position up, the hairspring comes out of the collet and heads up (toward the stem on a pocket watch, or away from the stem on a wristwatch). The opposite position must suffer.

A six position watch was a bit of a sham. They relaxed the allowed errors on the top three positions to bring the sixth position in a little closer. A five position watch actually has closer tolerances over those five positions than a six position watch.

Anyway, any error of over a minute in any of these positions indicates a major mechanical problem, not a slightly out of poise balance or hairspring.

Don
 

Ansomnia

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Don, thanks for your summary guidelines on how to adjust a watch.

The orientation of where the (resting) spring is attached on the collet was what I was wondering about but since there were no photos of the movement showing that relative to the pendant I did not want to elaborate in case it wasn't relevant.

What made me curious was that the 1000 position is opposite to the 0400 position. With a collet pinning effect, the timekeeping error manifestation is exactly the same as what Dave related from the watch's owner - the errors at 1200 and 0600 are opposite just like Dave's 1000 and 0400 are opposite. But I suspect mindful watchmakers generally pin the springs relative to pendant positions in an "adjusted" watch. Otherwise I imagine it would complicate the adjusting of the "useful" positions. This is why I asked Dave to make sure the standard positions did not actually register worse timekeeping errors.

From my cursory reading of Jendritzki, my take on the 6th position is also that it isn't really useful because that is the position which the watch is very unlikely to be used or placed in for any significant duration. I suspect it was more of a marketing gimmick.


Michael

P.S. I forgot to say I agree the reported errors are large for such a watch but I think all positions should first be accurately timed before "jumping in".
 
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fuzzuki

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I think the best solution at this point would just to let the customer wear the watch and see what kind of time keeping he gets.

Get the watch back and adjust it to keep time the way it is running now.

ie. If he said it runs 1 hour fast when worn.(per day.) Ajust it 1 hour slower than what it's running now.

OK, timing may be way out of wack. But if that's what it takes then so be it.

The wacth should be worn in the pendant up position put down at night with dial facing up.

If you don't understand how to fix watches, this may be the quickest way to make the customer happy.
 

Dave Berghold

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I think the best solution at this point would just to let the customer wear the watch and see what kind of time keeping he gets.

Get the watch back and adjust it to keep time the way it is running now.

ie. If he said it runs 1 hour fast when worn.(per day.) Ajust it 1 hour slower than what it's running now.

OK, timing may be way out of wack. But if that's what it takes then so be it.

The wacth should be worn in the pendant up position put down at night with dial facing up.

If you don't understand how to fix watches, this may be the quickest way to make the customer happy.

I do know how to fix watches..... I'm simply asking this board for a way to bring this particular watch back into adjustment...... Is there something wrong with a watchmaker trying to achieve something more than mediocrity? I don't want my customers to settle for anything less than I can offer and if all YOU have to offer is "the quickest way to make a happy customer" then so be it, they are your customers.... That is not my business method. Thanks for trying.
 

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