Ringin’ the bell…

[tmac1956]

All:

I just finished servicing an Elgin 18s full plate 17 jewel Elgin pocket watch and found something interesting that I thought I’d share.

When I first got the watch, it would run for a while and then stop. After a few months, it finally got into a non-functioning state. So, I took it apart and found that there were no cracked jewels or bent pivots and surprisingly little wear for a 1904. So I cleaned and oiled it, replaced the mainspring, and reassembled it. But I noticed that when I wound it up full and placed it on a table crystal side up, the watch had a noticeably unusual sound to it. Further, when I placed the watch up to my ear, the “tick-tock” had something of a harmonic with it – more on the “tick” side than the “tock” side. This is going on regardless of the position of the watch. Additionally, when I lightly tap the back of the watch, that same harmonic occurs which makes the watch sound like the ring of a bell. She’s strongly ticking along, keeping good time, and I’m getting 33 hours out of a single wind. After the watch runs for a few hours, this effect disappears.

Now, I know enough about structural mechanics (I know – you are probably surprised by that) to understand that the mainspring puts twisting forces into the watch frame through torque, but I’ve never heard one behave like this before. I suppose that if the watch plates are made from bronze (and the case is coin silver which tends to have a ring to it too) then this kinda’ makes sense. However, since Elgin surely designed their watches beefy enough to overcome said forces, this makes me wonder if maybe there’s something else going on here.

Anyway – something to think about.

Happy Independence Day everyone!!!

Tom

[randy]

Tom,
I’ve also noticed the small sounds in older P/W’s that make you go “HMMMMMMM?”
I think that your theories around what’s causing them are real possibilities. Different case materials would definitely produce different echo/harmonic effects.
I can hear differences at times, from listening to the front of the watch to the back.

It’s good you have this sensitivity, as it helps in your diagnostic abilities !

Have a great and safe 4th !!

all the best,

Randy

[willofiam]

Howdy yall, cant say I know about or have even heard of what you are saying but I wonder if it has to do with the hairspring ringing and being amplified?, Tom, you say it seems to be more apparent on one side of the escapement than the other, leading me to this thought. you guys are GREAT, I love it when these type of things come up…..William, now for some coffee. have a great day and be safe out there

[david pierce]

Tom,
Power the watch down and then give it just one wind. If you don’t hear the sound give it two winds and so on until the sound starts. This will let you know if the mainspring tension is causing the sound. The mainspring may be too strong for that particular watch.
david

[tmac1956]

david:

That was my thought as well as it only does it on a full wind and then stops after an hour or so. When I got over 30 hours from one wind that sounded suspicious as well. If it is too strong then I’m not sure what to replace it with as the one that I installed is the one called for by the Elgin documents. Do you pull it out and just saw it shorter? I’ve never cut spring steel and I’m thinking it might shatter on me. I have a pair of old mainspring punch pliers and I’ve experimented with punching new end holes on old mainsprings – they shatter just like glass. I guess you just anneal the end or something.

Thanks!
Tom

[arutha]

Hi Tom,
that is a strange problem and one I have not yet come across. Before you shorten the spring first check the running duration of the watch, also there is a rule for how much space there should be in the barrel once the spring is installed, I think it may be half or a third?. If after this you do still need to shorten the spring then you can just cut off what you dont need (the spring wont shatter when you do this ) but you will need to soften the end to punch or drill the new hole. I have found the best way to do this is to have the part of the spring you want to soften protruding from your bench vice, heat it to a cherry red and draw the heat source away slowly. The vice acts as a heat sink and stops the heat affecting more of the spring than is needed. Make sure you clean up around the hole once it is made as this helps to stop a potential tear.
Good luck,
Paul.
p.s. I am sure you already have but have you checked the spring thickness against the original spring?

[tmac1956]

@Arutha wrote:

Hi Tom,
that is a strange problem and one I have not yet come across. Before you shorten the spring first check the running duration of the watch, also there is a rule for how much space there should be in the barrel once the spring is installed, I think it may be half or a third?. If after this you do still need to shorten the spring then you can just cut off what you dont need (the spring wont shatter when you do this ) but you will need to soften the end to punch or drill the new hole. I have found the best way to do this is to have the part of the spring you want to soften protruding from your bench vice, heat it to a cherry red and draw the heat source away slowly. The vice acts as a heat sink and stops the heat affecting more of the spring than is needed. Make sure you clean up around the hole once it is made as this helps to stop a potential tear.
Good luck,
Paul.
p.s. I am sure you already have but have you checked the spring thickness against the original spring?

Arutha:

I didn’t mic the old spring because I ordered a factory replacement – at least it was in an Elgin envelope. I did order it from a source that I’ve used many times before. I’m guessing now that not comparing it with the old one was a mistake…

Hey.. thanks for the info on anealing and re-punching the spring!

Later,
Tom

[david pierce]

Tom,
Your punching tool will behave like any other punch and die. The one you have was probably used for many years and will need to be resharpened. Check the punch and die under magnification for any worn areas or chips around the edges. The die must be ground flat past any chipped areas around the lip. The same thing goes for the punch but when you resharpen it put a slight angle on it. This will reduce the penetration force and allow the metal to be sheared more easily.
Also, if you have an electronic watch analyzer it will probably indicate that the watch is overbanking. The spring could be too thick but there are also other factors such as the composition of the metal and the hardness and structure from the heat treat process.
david

[Bob Tascione]

Hi all,
Good topic Tom!
Before modifying the spring you may want to compare it’s dimensions to those called out for that watch. The spring is likely to be ok. I have found that ringing is fairly common in those older pocket watches using hard high carbon hairsprings. If the conditions are just right between case, balance amplitude etc. then things can begin resonating. Might explain why your watch is ringing when fully wound then drops off after power and balance amplitude decrease. If the watch isn’t re-banking from too much power (listen for a galloping sound) then probably isn’t anything to worry about as long as the rate isn’t gaining during that first hour or so.

Bob

[tmac1956]

David:

Thanks for the info on the punch. I just pulled it out and it needs to be sharpened for sure. I seem to be developing a tendency to just lightly touch things to my own detriment. I suppose there are drugs for that.

Anyway, I don’t have an electronic timing device, so I’ve just been checking them in five positions which takes about a week to complete per watch. Clearly, at this point that’s not problematic but as I get further into this, it will become so. Right now all my funds are going for machine equipment. The timer is, however, on my list.

Thanks again for the information.
Tom

[tmac1956]

Bob

Well, I’m glad to hear that the ringing isn’t too uncommon – I feel better now. I haven’t noticed a galloping sound and its keep really good time, running about 33 hours on a full wind. I was surprised at how good this one looked internally – very little wear on the pinions and the jewels were in good shape (for a change). It was just dirty and devoid of oil. I could probably have put the old mainspring back in, but following your training, I just went ahead and put in a new one.

I think I will start putting a mic and a Denison gauge on the old mainsprings to compare against the new spring and those data listed on the mainspring envelope – just to be safe that is.

Thanks for commenting.
Tom

[Bob Tascione]

Hi Tom,
Sounds like it’s a strong runner. Good job!
Rather than saying “fairly common” I probably should have said not terribly uncommon! lol. You probably won’t run into it that often but it does happen. It’s also sometimes referred to as ‘singing’. If you replaced the old blue mainspring with a new alloy spring of the same dimensions then it’s possible that the watch may be a little over powered and might still be knocking (rebanking). A timing machine would tell you immediately but there are ways around that if you don’t have one yet. If you can amplify it a bit you would know for sure. The galloping sound is unmistakable. Since you’re getting a nice full run out of it then the spring is most likely at it’s optimum length. If that’s the case then shortening (or lengthening) the spring would just result in a shorter run time but wouldn’t lessen its strength so no reason to cut it as you mentioned in your earlier posts. These alloy springs can be a little stronger than the older blue springs of the same dimensions. Not usually a problem but it “isn’t terribly uncommon” either …lol.

Hope this helps. Let us know how it goes Tom,

Bob

[tmac1956]

@Bob Tascione wrote:

Hi Tom,
Sounds like it’s a strong runner. Good job!
Rather than saying “fairly common” I probably should have said not terribly uncommon! lol. You probably won’t run into it that often but it does happen. It’s also sometimes referred to as ‘singing’. If you replaced the old blue mainspring with a new alloy spring of the same dimensions then it’s possible that the watch may be a little over powered and might still be knocking (rebanking). A timing machine would tell you immediately but there are ways around that if you don’t have one yet. If you can amplify it a bit you would know for sure. The galloping sound is unmistakable. Since you’re getting a nice full run out of it then the spring is most likely at it’s optimum length. If that’s the case then shortening (or lengthening) the spring would just result in a shorter run time but wouldn’t lessen its strength so no reason to cut it as you mentioned in your earlier posts. These alloy springs can be a little stronger than the older blue springs of the same dimensions. Not usually a problem but it “isn’t terribly uncommon” either …lol.

Hope this helps. Let us know how it goes Tom,

Bob

Bob:

I’ve been meaning to pick up a little Radio Shack microphone/amplifier for that purpuse, but just haven’t gotten around to it. This a good excuse make the time.

Thanks!
Tom

[david pierce]

Tom,
I don’t know what the timing machines cost now but I paid less than $200.00 for mine a few years ago. They can give you a lot of information about the condition of a watch.
david

[tmac1956]

David:

What type of timing machine do you have?

Thanks!
Tom

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