Would any of the Elgin experts know how long Elgin used a "stop works" on their 18 size mainspring barrels. I picked up a extremly nice B.W.Raymond keywind # 38531. The oil in it looked like it was from 1870 and nothing moved. Upon disassembly I found this type of arrangment on the mainspring barrel and was just curious how long they used that. I have another Elgin in the 75,000 range and it does not have it.. Was it maybe used in only certain grades??? Any help would be greatly appreciated..

Regards,
John Pavlik

P.S. Elgins are getting interesting

John,

Good question! I remember running into one of those. I believe it was on an early BWR stem wind. I have a videotape that describes how to properly set the stop works so it will function properly. If I'm not mistaken, a lot of these disappeared from movements because many watchmakers didn't know how to reassemble them and left them out.

Next time I look at the tape, I'll try and capture the serial number of the movement being worked on and also see if it's a BWR. This may have been used exclusively on Elgin's higher grades.

John D. Duvall
Vice President, Education

I don't know the exact dates or serial number ranges when Elgin used stopworks, but at the time they were used, they were the only "safety" devices the watches had to prevent damage from mainspring failure. Once the "safety pinion" was developed, stopworks were rendered essentially obsolete, although it's certainly possible that both were used simultaneously for a brief period.

Mainsprings can break at any time, but the vast majority of breakage occurs at full wind, when the stress on the spring is greatest. Stopworks prevent a spring from being wound fully, and they also prevent it from running all the way down. Essentially, they restrict the normal operating range to the "middle" part of the mainspring wind, and by so doing, they obviously restrict the duration of run on a wind.

Most typical watches with "going barrels" will run about 40 hours on a full wind, assuming both the watch and mainspring are in good order. Most stopworks, however, mechanically limit the barrel arbor to about 5 turns, which is typically only enough for 30 hours of running (most center pinions have 12 leaves, while most spring barrels have 72 teeth, therefore meaning that most spring barrels rotate once every 6 hours).

In my opinion, watchmakers typically removed stopworks in order to extend the running time of the watch, but that's really just an "educated" guess to explain why people so frequently did something they shouldn't have. I'm at a much greater loss to explain why dust bands were so frequently left off of movements that originally had them.

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Steve Maddox
Past President, NAWCC Chapter #62
North Little Rock, Arkansas
IHC Charter Member 49

John and Steve,

Thanks for the information. John if you happen on to the tape, I would be interested in the serial number. Steve it has 4.5 complete turns for a full wind. I am seeing how long it will run.. Interesting though, Elgin lists mainspring barrels with 60 and 78 teeth and main gear pinions with 10, 11, and 12 teeth. But I did not count them on this watch.... dust rings missing, maybe ploy to increase "Watch Cleaning sales", or did they not really work for keeping the dust out....

John Pavlik

John,

I will make a note to search for it. Did you take your BWR down to the point where you had to reassemble the stopworks? I agree with Steve that the works were probably removed to increase the run time, especially on watches with safety pinions. I also believe that many of the 20th century watchmakers may have come across these for the first time and had difficulty figuring out their function and/or how to do the reassembly.

The dust bands on the older 18s watches and the newer dust rings probably kept everything out of the movement that was hostile, except dust. If you've ever lived in a desert environment, you'll know what I'm talking about.

John D. Duvall
Vice President, Education

John,

The different Elgin barrels you noted are probably for watches with "fast-train" or "slow-train" gearing. Needless to say, coarser teeth are found in slow-train models, while finer teeth are found in fast-trains. It isn't surprising that the Elgin material book shows some of their models having a few more teeth than "average," while others have a few less.

Your watch probably has a "slow-train" movement, in which case, according to the Elgin list you quoted, it probably has a 60-tooth spring barrel, and a 10-tooth center pinion. That's still a 6:1 ratio (the same as 72:12), and if you wound the barrel arbor 4.5 turns, it should power the movement for about 27 hours. (My guess is that if the movement and spring are capable of running for the entire possible duration, the watch will run about 28 hours, or a few minutes more).

From what I recall, ordinary "Maltese cross" stopworks are supposed to turn 4.8 turns (or thereabouts) from one extreme to the other. Some stopworks, however, have an extra notch, in which case they could turn approximately 5.8 turns.

"Dust bands" did work to keep a good amount of dust and lint (especially lint) out of the movements, but as John suggests, they certainly weren't 100% effective. I've removed movements with dust rings from hunting cased watches, and actually had "dust bunnies" fall from the inside of the case where the lift and latch springs are contained!

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SM

John,

Everything was disassembled Except the barrel, I thought I would get some information first. I seriously doubt the movement was ever cleaned. The plates sparkle like they are new..The cleanest American watch that I have seen yet..Has a very nice W. P. & Co. Coin open face case, that is almost as new as the movement. Runs great and now keeps great time...

Steve just in case you want to know, it ran for 28 hours and 45 minutes on a full wind...losing about 3 minutes in the last 1/2 hour before it stopped..

Thanks to both for the great information..

John Pavlik

Six hours of running time per revolution of the mainspring barrel, multiplied by the 4.8 turns of the winding arbor allowed by the stopworks, comes to 28.8 hours, which is 28 hours and 48 minutes. That differs from the actual recorded running time by 3 minutes, which is an overall accuracy rate of 99.83%.

Of course, it could have just been a lucky guess........



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SM

Steve,

Ya think I should tear it down again and see if I can get the last 3 minutes out of it..

John

Besides, depending on how the teeth of the ratchet happen to fall, you will get a few minutes variation from time to time anyway.

I can't recall how many teeth the ratchet wheels on KW Elgins have, but I'd say about 20. If that's the case, then each click would be 1/20 of a revolution of the barrel arbor, which would power the watch for 1/20 of 6 hours. That's a possible variation of as much as 18 minutes, depending on where the ratchet click happens to fall at the instant the stopworks engage to prevent additional winding.

In reality, I knew your watch SHOULD run something in excess of 28 hours, but short of 29, and the fact that it turned out so close to the mathematical "ideal," really was just an accident. The next time you try it, the result is almost certain to be a bit more, or a bit less.

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SM