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centerwheel

What can cause rate to cycle every 5 minutes?

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I have an issue with an antique Hamilton 974 pocket watch (circa 1912). The watch has been recently serviced including jewels and gears inspection, new mainspring, cleaning and lubricating. Balance wheel swings freely with good amplitude (270 degrees), beat error is 2.4ms (can be improved), the rate after some adjustments is now fairly consistent in all positions.

The problem shows on the timographer as slow but regular oscillation of the rate. The oscillation cycle is exactly 5 minutes. The maximum difference in rate between low and high is approximately 30 seconds per day. During the slow rate of the cycle I can also see lower amplitude (250 degrees) and an increase in beat error to 2.7ms.

This watch escapement is 18000 bph. The only gear that rotates close to 5 minutes is third gear which, however, makes one rotation every 7.5 minutes. Anyway, just to be safe I replaced the third gear but the problem remained.

What can be the cause of such a behavior? What kind of defect can produce such a cycle? 

Or, perhaps it's just something that might occur in an antique escapement? "The nature-of-the-beast"?

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I've seen this before and I agree with nickelsilver It's the teeth of the barrel mashing with the pinion of the center wheel.  The watch I had somebody had substituted a different mainspring barrel and it was a very severe issue until I got a replacement barrel. Basically couldn't even time the watch at all.

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1 hour ago, nickelsilver said:

What's the tooth count of the barrel and center pinion? I'm suspecting a depthing problem due to worn center plate and bridge holes.

I agree that this is his problem. he probably has a pivot or two of worn on one of the wheels . Unless it is a tooth of one of the wheels that is worn and that the watchmaker has not seen. It happens sometimes too

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3 hours ago, JohnR725 said:

I've seen this before and I agree with nickelsilver It's the teeth of the barrel mashing with the pinion of the center wheel.  The watch I had somebody had substituted a different mainspring barrel and it was a very severe issue until I got a replacement barrel. Basically couldn't even time the watch at all.

I haven't thought about that. I have have another barrel and a center wheel, so, I will be able to swap those.

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4 hours ago, centerwheel said:

I haven't thought about that. I have have another barrel and a center wheel, so, I will be able to swap those.

Before swapping the parts why don't you look at what you have to see why they're not working?

Then parts swapping on American pocket watches? On modern Swiss watches you can swap just about anything they interchange. But you want to be really careful with parts swapping on American pocket watches because a lot of times the parts were hand fit. So swapping your way out of a problem may actually make new problems. Which is why we need to find out why the current parts don't work? 

 

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American movements especially after the turn of the century were completely non-hand fitted. What can crop up is differences in grades for the same base caliber. But a part for Hamilton x caliber will fit x caliber.

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3 minutes ago, nickelsilver said:

American movements especially after the turn of the century were completely non-hand fitted. What can crop up is differences in grades for the same base caliber. But a part for Hamilton x caliber will fit x caliber.

   not true;  vin

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   not true;  vin
Not sure on which point you disagree but interchangeability was the corner stone of U.S. watchmaking. That said many of the movements have been massacred so maybe a jewel was replaced with the wrong one and the pivot adapted or a fork that was close mashed in somehow, etc.

I've been across the pond a couple of decades but still see an American pw here and there. Last was a "maker" who recased old Elgins in wristwatch. Customer brought two of them for service (they were supposedly restored by the "maker"). Broken hs collet glued, escapement berzerked, dial glued on, balance pivots grooved, holes smashed closed, not untypical of stuff I saw regularly 20 years ago.

But aside from maybe Howard or some of more boutique manufacturers no way they were hand fitting parts at Waltham Elgin Hamilton with the production numbers they were hitting. The finishing techniques for pivots for example may have been labor intensive but they were made to standards. The U.S. smacked the swiss so hard they had spies bringing back intel on manufacturing methods. Which they improved upon, and eventually smacked back with.

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The reality versus the fantasy of interchangeability of American pocket watch parts? By the way if you haven't seen the video below it's quite interesting from the 30s. If you look at the video one of the reasons Elgin made so many watches was its factory was really really big. The number of people was huge was probably one of the largest companies in the world at one time as a guess. Multiple generations of Elgin families worked at the factory. So by the 1900 production methods improve machinery improves Elgin takes great pride which you can see in the video and making sure everything fits perfectly. But still a lot of and work hand fitting hand adjusting with a huge volume of people.

So the problem with this conversation as we can all pick and choose examples to make our point which doesn't necessarily help with the original problem. For instance the second link turn-of-the-century mass-produced watch. Made for a whole bunch of years listed as a model three. Go to the website you'll find a lot of 12 size model three watches. Illinois parts catalog is rather interesting the parts are listed by name of the part then on the page illustrations the size and then the model. Canon pinion for 12 size model 1 to 5 all identical. Only one part numbers listed reality they do not interchange. They may have been mass-produced in a turn-of-the-century factory but notice how there made in batches. There's still a lot of hand fitting and adjusting true they're going to be better than cottage industry European watches but.

So back to the original question swapping parts to fix the problem is a bad idea unless you know why your swapping the parts. So we think we know where the problem is let's look at those parts to see why there a problem. Then once we figure out why you have a problem what the problem is then we can figure out how to solve the problem.

 

https://www.youtube.com/watch?v=ys4ChOWYNy8

http://illinoiswatchguide.com/gradeautocrat.html

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   here is a story about Swiss made watches -- i heard -- it may be true:  they boasted making "the smallest watch screw" and sent it to Japan.   the Japanese drilled a hole thru it and sent it back to the Swiss !    vin

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4 hours ago, vinn3 said:

   here is a story about Swiss made watches -- i heard -- it may be true:  they boasted making "the smallest watch screw" and sent it to Japan.   the Japanese drilled a hole thru it and sent it back to the Swiss !    vin

Iranians tell a similar story , Britts made and sent to Germans, a wire placed inside a strand  human hair,  Germans drilled a hole in the wire, stuffed the hole with human hair and returned.

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Well, I buy non working American pocket watches, sometimes even missing parts, and resort to swapping parts routinely to get them fixed. In rare cases I have to make the part that I need because I can't find those ready available. It gets sometimes very challenging and often frustrating, but it feels good being able to make a balance staff for an old 18s watch based on hand measurements and eyeballing of what's available (old, broken staff, etc).

In the case of this watch I swapped(!) the center wheel and the problem just went away like magic. No more cycling through the rate. There is still some irregular cycling of just a few seconds/day, but that is pretty much expected on those old watches. I've used the opportunity, with the balance out of the watch to improve the beat error down to 1.6ms - I am totally happy with it. Thank you all who suggested the cycling problem to be caused by the center wheel pinions or the barrel! It was.

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On 2/25/2019 at 8:46 PM, vinn3 said:

   here is a story about Swiss made watches -- i heard -- it may be true:  they boasted making "the smallest watch screw" and sent it to Japan.   the Japanese drilled a hole thru it and sent it back to the Swiss !    vin

What I heard (60 years ago....)  They threaded it and screwed on a nut.  At one time the story involved The Americans and the Swiss.  Had to be true at some point :biggrin:

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