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Rentfro1444

Sealed mainspring barrel for Longines Grand Prize Automatic

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My late wife gifted the above noted watch to me in 1962.  It’s a 14 kt, 340 movement that began to stop after several hours of wear.  If I hand wound it 10-12 times, it would run for 2-3 hours and stop.  Off to the repair shop, where I was told it needed a rotor axel, which they said they could not find.  It took no time to find and purchase that part, new in factory envelope on eBay from from a pleasant gentleman in Great Britain. Having lost confidence in the original repair shop, I took it to another well regarded watch repair establishment along with the rotor axel.  After several weeks, they informed me the watch needed a new mainspring, which was in a sealed barrel, and was unobtainable.

After reading on-line watch repair discussions and articles about the difficulty of obtaining parts for watches such as mine, I joined your forum to avail myself of your expert opinions on what can be done to bring back to life this excellent timepiece that has such fond and sentimental memories attached to it.

i have read that it is possible to “open” the barrel of a 340 sealed mainspring using great caution not to damage it, replace the spring then re-close the barrel. Can anyone tell me if the aforementioned procedure can actually be achieved successfully?  Your comments on other possible solutions will be anxiously awaited.

Rentfro1444

 

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You are correct the mainspring is in a sealed unit see service below. Hopefully the fault is not the mainspring.  Although found this on ebay by the look of it the barrel can be opened much the same as Seiko barrels which are supposed to be sealed. 

https://www.ebay.co.uk/itm/Parts-Longines-340-Choose-From-List/274345305610?hash=item3fe041260a:m:m2VrcXcjBsMeZIGhZgnxPYg

 

SERVICE:

 

https://watchguy.co.uk/service-longines-automatic-calibre-340/

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Thanks, Clockboy for your prompt reply.  I had previously  read the post you referenced in an attempt as a layman to inform myself as much as possible the cause/causes of my watch’s malfunction.

While I informed the last watch repairer when I took the watch in that it’s mainspring was sealed, their response was they probably had one in stock. And a watch if that would need a new mainspring.  How they could deduce that from the symptoms I provided is above my pay grade. 
 

So the question I pose is this:  is it possible to successfully unseal the mainspring barrel, replace the spring, and reseal the barrel?

Has anyone done this before?  A layman wishing his watch can have a miracle resurrection, due to the knowledge and skill of the professionals who populate this forum.  
Once again, thanks for reading.

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It looks like yes. I have not worked on this caliber but looking at the pics on eBay it seems the barrel can be opened. If so the mainspring could  be removed and be measured and a replacement could be found.  

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s-l1600.jpg

The barrel appears to be sealed with some sort of riveted arrangement on the lid, and possibly peened at the edges. If you knew exactly how it was fitted together, it should be possible to open it.

This looks like an operation that would require care, to ensure you didn't destroy the lid. I suspect a skilled watchmaker should be able to do this, but I also suspect that a lot of people would judge it too much trouble, and just tell you the part is not available.

In theory, it would also be possible to make a replacement barrel, and/or lid but that would require a level of engineering that puts this well out of the economical to repair category. Fine if you were going to produce 1000 and sell them, or if you were doing it as a hobby, and the time spent wasn't being charged out to a customer, but not for a one off repair.

The part *may* be available to genuine Longines service centres, so you could try them. Expect to pay Longines prices to get it fixed though.

Edited by AndyHull

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Thanks, Andy.  I’m going to try to send you a pic of an opened 340 barrel with enclosed spring that I purchased.  It is a pre-owned  part.  If you get the photo, please let me know what it looks like, and I’d appreciate any one else’s view as well

5ED8AB99-8D86-4BDE-9B77-4221C754FE5C.jpeg

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5 minutes ago, Rentfro1444 said:

I see the pic came through - gives me hope I’m not completely clueless.  Thanks to every one who checked it out; am anxious to get your responses.  Thanks again, Andy.

 

It looks well used, but complete. My guess is that someone has carefully skimmed off the rounded over (riveted?) top to get in to it. I suspect this shouldn't present any issues. I guess the only way to see if it actually works is to try fitting it.

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I have not as yet received the part, now face another quandary;  I have no idea what kind of price the replacing of the rotor axel and mainspring, along with cleaning should be expected.  The two entities I dealt with in the states had widely differing estimates..  I recognize charges can vary, I’d just like to get some idea of a reasonable estimate for the work.  I’m mindful of the axiom “You are not just paying me for what I do, but the years I spent learning how to it.”


Best Regards,

 

Rentfro1444

Jim Mallett

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These sealed units can be opened as you have found - and re-closed. I have done it with no consequence.

Regarding cost for the work, here is the price list of watch repairs in the UK by Watchguy.

https://watchguy.co.uk/price-list/

Here is an example of a Longines cal 340 repair

https://watchguy.co.uk/cgi-bin/library?action=show_photos&wat_id=1713

You could consider sending the watch to the UK for repair.

Edited by Watcher
addition

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Regarding the discepancy in prices, you need to be sure they are offering the same thing. Replacing a mainspring barrel and a rotor axle will not take much time, but a good watch repairer will likely consider a complete service necessary, which involves a complete strip-down, thorough cleaning and inspection of all components. If the watch hasn't been serviced recently, it's due anyway. If you want confidence that this important watch is in good hands, I understand the NAWCC has a list of registered repairers.

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Thanks, Klassiker, for the referral to check NAWCC for registered repairers.   Regarding the previous repairers, the activity was to provide a full cleaning for a stated charge, plus the costs of any parts.  One entity quoted $250.00 for the service, said the watch needed a rotor axle, but returned the watch because they could not locate that part.  (It took me 45 minutes to find the axle; but perhaps they just didn’t want to go to the trouble).  The other verbally quoted $350.00, but on the printed estimate that figure became $450.00, and I was told they could not find the necessary mainspring, which cost they listed at $87.00. ( I wondered how that figure was determined if they could not locate the part.)    So you gather correctly that I was concerned about my watch being in the right hands after these two experiences.
 

Thanks again  for your kind help.  Takes me back to the days you could reliably do business on a handshake.

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I agree most of the time the sealed barrels are actually serviceable. One exception I can think of is Zodiac, can't recall the caliber; the cap was so well burnished in that it was too distorted after removing to use. I ended up making a new cap for that one.

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I have posted a picture of the opened barrel and mainspring I have purchased.  I came across a listing described as follows:

340-180/1 barrel with arbor complete With mainspring sealed

what is this part?  What is an “arbor” is this part the same as a “barrel complete”?

Thanks for the explanations in advance.

Rentfro1444
 

 

 

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On 5/10/2020 at 5:38 PM, Rentfro1444 said:

 

340-180/1 barrel with arbor complete With mainspring sealed

The barrel is the can that holds the spring, this is usually in the form of a hollow brass drum section with a gear cut on the base, and a lid.
Inside the barrel there will be not just  the mainspring, but also the shaft that connects the center of the spring coil to the winder gear, this shaft is the barrel arbor. (There are other arrangements, but this is by far the most common).

In this case, all of these parts are supplied as a single sealed unit.

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