Help w/ Hairspring ST 125 movement

Swanicyouth

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Hi all. Picked up this Seth Thomas nautical banjo # 2; I believe from about 1927, today.

9E71A30C-9A23-413E-BD89-E6BB7B667C58.jpeg

Was very surprised to crack it open & see no pendulum! Not familiar with this type of escapement - I’ve only worked on pendulum movements. Other thank that, it’s dirty - but in good shape. Finish looks pretty ok - but may not be original as I see some drip marks in the back. Otherwise, cosmetics are not bad.

The clock looks complete & not monkeyed with too much - but the back cover is missing - easy fix there.

435EB904-B41C-4BB7-ACA5-DD4A2E22EEB8.jpeg

So, I started to do some reading on hair springs & balance wheels before touching it. The springs seem good - they wind & hold power & are in barrels.

The hairspring mechanism will not stay running. I’ve read this could be due to the coils touching each other (seems ok), dirt, or possibly even it being magnetized. Or, could be something else for all I know.

I noticed little spaces in the balance wheel - which initially made it look “broken” to me. Upon trying to get a picture of those (in red) - I noticed the hairspring seems “magnetized” - it wants to jump up towards the metal pick.

Again, I have 0.0 experience with these - so I could be completely wrong. Also, it looks like the balance wheel will run a few jerky back & forths & just stop. The ring doesn’t seem like a perfect circle as well… Almost like it’s out of round? It may look like it in the pic - but I really was not putting any pressure in the ring.


DD00F35D-F6B9-459F-A293-69925FE53971.jpeg

Any guidance we’re to start or any issues obvious? I know it needs to be taken apart & cleaned / oiled. But, if it’s something silly I’d like to see if I can get it running before taking it apart - that way I would know it worked prior to servicing.

I’m guessing this movement may be covered in Conover’s ST book - which I’ll likely be getting once I read what I have… Anything basic I just could be missing?

Thanks…
 

shutterbug

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It's probably not the balance wheel or hair spring that is the problem. They get scrutinized first by people new to clocks, but are typically not the fault. I suspect you have issues with the pivot holes being worn into an elongated shape. That robs power from the whole train and the clock stops. A magnetized hair spring is an issue though, so it will need to be de-magnetized when the other issues are found and corrected.
I don't recall seeing a wheel split like that though. That's a bit strange.
 
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Dave T

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Actually this is the first movement of this type I've seen for Seth Thomas, but as for the balance wheel splits, that looks perfectly normal to me. But the wheel should be completely symmetrical. (both ends of the split should be in alignment) It's very common on most pocket watches to have a split wheel.
 
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Swanicyouth

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I don't recall seeing a wheel split like that though. That's a bit strange.
Thank you. I found another pic of a ST 125 balance wheel on this forum & it seems to have the same splits:

Mine:

87778496-3E72-4833-92B9-72EC52CF8077.jpeg

Other:

F613D520-0CDF-4819-A29C-41F558D734D4.jpeg

So, what you are saying is, look for reasons similar to pendulum movement reasons why it won’t stay running? Any idea how to “demagnetize” the thing & how could it get that way in the first place:???:
 

Swanicyouth

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Actually this is the first movement of this type I've seen for Seth Thomas, but as for the balance wheel splits, that looks perfectly normal to me. But the wheel should be completely symmetrical. (both ends of the split should be in alignment) It's very common on most pocket watches to have a split wheel.
Do you think that wheel can be ever so carefully “tweeked” back so it’s in round?
 

gmorse

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Hi Dietofnothing,
I found another pic of a ST 125 balance wheel on this forum & it seems to have the same splits
This is a temperature compensated balance, the rim is a layer of brass on the outside and steel on the inside. As the temperature rises, the brass expands more than the steel and this moves the rim inwards, speeding up its oscillation, which it can do because of the splits. As the temperature reduces, the opposite happens and the rim moves outwards. This is all to compensate for the balance spring's reduced elasticity as the temperature rises, which would effectively slow the balance without the compensation privided by the bimetallic rim. This is perfectly familiar to watch folks, as Dave T said.

Do you think that wheel can be ever so carefully “tweeked” back so it’s in round?
Yes, that's possible, although from your picture I'd say that the balance spring, (aka 'hairspring'), is not centred properly and may not be correctly fitted in the regulator pins or else it could be snagging somewhere, which will prevent the balance from oscillating. The slight distortion in the rim shouldn't by itself prevent it running.

Regards,

Graham
 
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shutterbug

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Thanks to you watch guys for that clarification. My point, Diet, is that you are likely looking in the wrong place for your problem. It COULD be the balance wheel or hairspring, but the odds are against it. It's more than likely a problem lower in the train.
 

Swanicyouth

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Somehow my account got messed up & I thought mod reset it to new email - but it appears I’m a new member again…

Anyway, got the clock apart the movement was very clean. There was no real oil or sludge on anything. Right away, this movement looked diff than older American movements I’m used to - it’s hairspring & rack and snail.

The bushings showed no real sign of wear. Nothing look bent, broken, or damaged. Someone may have been working in her before as there is a “t” etched on the time spring barrel.

image.jpg

I oiled the movement because it was pretty dry & cleaned it w/o disassembly. I was still hoping to figure what was wrong with it before taking it apart & I noticed the gear lever for the speed adjustment was all the way at the end of its travel. Set it to middle - and now it runs.

Not sure if speed lever torqued to 1 side or the fact it was dry was the issue. I but a drop of oil on hairspring as well. I figured if there was a real issue it wouldn’t hurt & not sure if they are supposed to be lubed or not; but I doubt it.

Now it runs like a top. Apparently? hairspring movements can have an issue where they can run too fast if hairspring is not right? Maybe that is going on with this & someone kept trying to slow it down. Running it on a test stand to see.

Video & pics:




593EB977-EABD-4AA9-9EDF-9F9A77534AEB.jpeg A0D22779-AF19-40E4-BEA0-0C01F1077FAB.jpeg E9086D55-A537-472A-ACBA-A707750335F0.jpeg 74C1C4B8-95AE-4E56-B2D1-C295416FE79B.jpeg C95513B2-6B8A-4579-AD59-E4BCF7492F0E.jpeg C49FB8E2-2447-48B2-9AB3-59BBAC612961.jpeg D5043605-2974-4E72-BDE7-A0AAF5422005.jpeg 8C250B94-F71F-481E-A159-9D98B367F6FA.jpeg 5168CBFC-6E5D-4BD2-813B-CAC63F32415F.jpeg I 1B6E7EF4-48C5-4916-BF37-1B5345693474.jpeg

image.jpg 593EB977-EABD-4AA9-9EDF-9F9A77534AEB.jpeg A0D22779-AF19-40E4-BEA0-0C01F1077FAB.jpeg E9086D55-A537-472A-ACBA-A707750335F0.jpeg 74C1C4B8-95AE-4E56-B2D1-C295416FE79B.jpeg C95513B2-6B8A-4579-AD59-E4BCF7492F0E.jpeg C49FB8E2-2447-48B2-9AB3-59BBAC612961.jpeg D5043605-2974-4E72-BDE7-A0AAF5422005.jpeg 8C250B94-F71F-481E-A159-9D98B367F6FA.jpeg 5168CBFC-6E5D-4BD2-813B-CAC63F32415F.jpeg I 1B6E7EF4-48C5-4916-BF37-1B5345693474.jpeg image.jpg 593EB977-EABD-4AA9-9EDF-9F9A77534AEB.jpeg A0D22779-AF19-40E4-BEA0-0C01F1077FAB.jpeg E9086D55-A537-472A-ACBA-A707750335F0.jpeg E9086D55-A537-472A-ACBA-A707750335F0.jpeg 74C1C4B8-95AE-4E56-B2D1-C295416FE79B.jpeg C95513B2-6B8A-4579-AD59-E4BCF7492F0E.jpeg C49FB8E2-2447-48B2-9AB3-59BBAC612961.jpeg D5043605-2974-4E72-BDE7-A0AAF5422005.jpeg 8C250B94-F71F-481E-A159-9D98B367F6FA.jpeg 5168CBFC-6E5D-4BD2-813B-CAC63F32415F.jpeg 1B6E7EF4-48C5-4916-BF37-1B5345693474.jpeg
 
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Uhralt

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The action of the escapement in the video looks good. Neverthless i would suggest to remove the oil from the hairspring because it will give you problems later on. The oil will become sticky, attract dirt and will cause the coils of the spring to stick together. the clock will run way too fast before it eventually stops. If you don't want to remove the balance wheel to clean the hairspring you can use some q-tips soaked with acetone or fluid lighter gas to carefully remove the oil.
Uhralt
 
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Swanicyouth

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The action of the escapement in the video looks good. Neverthless i would suggest to remove the oil from the hairspring because it will give you problems later on. The oil will become sticky, attract dirt and will cause the coils of the spring to stick together. the clock will run way too fast before it eventually stops. If you don't want to remove the balance wheel to clean the hairspring you can use some q-tips soaked with acetone or fluid lighter gas to carefully remove the oil.
Uhralt
I think I’ll do that. I usually use Brake Kleen to clean oil off movements. I dunno if anyone else here uses it, but it’s pretty amazing & meant to be 100% volatile & not leave anything behind. It’s safe for aluminum & steel - that I know. I’m sure it can remove any coating on brass, but on raw brass I’ve used it many times without issue. Comes in a spray can, like carb cleaner, but doesn’t leave behind any oils like the former can.
 

shutterbug

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Like any clock, the balance has to be in beat. When your fast/slow adjuster was maxed to one side, it probably threw it out of beat far enough to prevent it from running. Keep us posted on how it's doing.
 

Uhralt

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I think I’ll do that. I usually use Brake Kleen to clean oil off movements. I dunno if anyone else here uses it, but it’s pretty amazing & meant to be 100% volatile & not leave anything behind. It’s safe for aluminum & steel - that I know. I’m sure it can remove any coating on brass, but on raw brass I’ve used it many times without issue. Comes in a spray can, like carb cleaner, but doesn’t leave behind any oils like the former can.
Brake Kleen should also work well for this purpose. Just don't spray it on because it will also remove oil to some extend from the pivot holes.

Uhralt
 
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Swanicyouth

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I will thanks. It’s keeping good time as of this morning. Movement is in a test stand but was like 2 mins fast with plenty of adjustment.

This probably is a really dumb question, but with hairspring type you don’t have to put it “in beat“ somehow? Or make any other adjustments unique to that type of movement?
 

shutterbug

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Yes, it needs to be in beat or very close. You should be able to hear a nice even cadence. The beat is adjusted by holding the collet with a small screwdriver or similar tool and turning the wheel. It's easy to mess things up if the screwdriver slips off, so take your time.
 

Uhralt

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If it runs well and with an even tick it is probably well enough in beat. Then I would leave it alone.

Uhralt
 
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Swanicyouth

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It’s running good & keeping good time on the movement stand - I’m not messing with it. My philosophy is, don’t go looking for trouble - let it find you lol
 

shutterbug

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It looks great!
 
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