6139 Mainspring Replacement

[jdrichard]

After servicing a South Bend pocket watch with a weak mainspring, I think the small amplitude and fast BPH on my 6139 is probably due to a weak mainspring and not magnetism or a dirty mainspring. So the question is; is there any way to remove the mainspring barrel on a 6139 without a full disassembly? And, where would the best place be to pick up a new mainspring?

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[oldhippy]

You will need to remove part of the watch but not all. When it comes to the mainspring barrel it doesn't come apart like most, its not meant to be taken apart, it should be replaced by a new unit, but I understand this day and age because parts can be difficult to obtain many on here take it to bits, you will need to part it with a very thin blade , it comes apart from the side. 

[rogart63]

Have you checked the bushings on the trainwheel bridge? And even the mainplate could get worn out  They need to be in very good shape. Otherwise the mainspring barrel could twist and lower the amp? That is what i think? And the mainspring is no big deal to remove and clean. And i think you could find some mainspring barrels from Speedtimerkollektion for the 6139 . BTW Seiko movements have low Amp. Usually a little over 200 BHP ?

Edited May 22, 2016 by rogart63

[jdrichard]

Do not not have to disassemble the complete watch down to the mainspring? Of can I lift a complete assembly. This is a complex Chrono??

This is what I did with a South Bend to test the strength of the mainspring

[jdrichard]

I actually thing that the hairspring is bunched up on one side. Is this magnetism ?

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[jdrichard]

https://vimeo.com/167623820

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[oldhippy]

I can't tell by the picture because its poor.

[jdrichard]

I can't tell by the picture because its poor.

It looks bunched up on one side, like the springs are touching. Hard to take a quality micro photo.

[rogart63]

Looks like it's very close in the bottom of the picture? 

Seiko hairsprings are usually very tight? I would remove turn it upside down and see how it looks when it's free? 

Bending the hairspring in the right place could make it run much better? 

Little more in where the red arrow is will make the hairspring go out where the green is? But you need to see how it looks before you do anything? 

[jdm]

I would not mess with this hairspring before you have acquired the skill and solid results at manipulating. It is one of the most difficult tasks ever and period. Ask me how do I know. Any alternative is better - from giving it to a watchmaker to leave it as it is. 

[jdrichard]

I would not mess with this hairspring before you have acquired the skill and solid results at manipulating. It is one of the most difficult tasks ever and period. Ask me how do I know. Any alternative is better - from giving it to a watchmaker to leave it as it is. 

I am a man of adventure. First thing I am going to do is demagnetize it. Then I will see if any part of the spring is stuck together. If not, I may be good, if so I may adjust it as was suggested.

[jdm]

7 hours ago, jdrichard said:

I am a man of adventure. First thing I am going to do is demagnetize it. Then I will see if any part of the spring is stuck together. If not, I may be good, if so I may adjust it as was suggested.

Seiko hairsprings are anti-magnetic. Magnetization is much, much less an issue to what often suggested. From the picture, the hairspring is distorted. That is a more common defect.

[oldhippy]

I'm sure if you go about it very carefully you will be able to sort out this task. Just be very careful with the hairspring.

[jdrichard]

Do you completely remove it from the balance cock?

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[jdrichard]

Seiko hairsprings are anti-magnetic. Magnetization is much, much less an issue to what often suggested. From the picture, the hairspring is distorted. That is a more common defect.

This is an early 1970 Pogue, would they have had antimagnetic hairspring back then ?

[oldhippy]

You can demagnetize the whole watch. You don't need to remove the balance from the cock. One way I used to go about it would be to wrap the complete balance in a small piece of tissue paper and demagnetize it then wash it out in a bath of ronsonol lighter fluid then use a blower to dry it then use the appropriate oil.

[vinn3]

right you are,  the balance and the cock  -  together.   this is  where magnetism usely effects timing.

[jdrichard]

So what do you think?

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[oldhippy]

After watching that, he made a lot of work for himself in removing the balance cock from the balance wheel, he never showed how to demagnetize the balance, which is what many on here would have liked to have seen. He did say how clean the hairspring was which It would not have been after touching it many times with his screwdriver.

[vinn3]

I tend not to  watch work  videos.  some of them are like the auto repair  videos ( some  showing  poor understanding or  knowledge AND  down right  un safe)  I guess I am an old bookworm.   (trained by  illustrations  and  print)..  at  least you  won't be crushed if a  watch  falls on you !   vinn

[jdrichard]

After watching that, he made a lot of work for himself in removing the balance cock from the balance wheel, he never showed how to demagnetize the balance, which is what many on here would have liked to have seen. He did say how clean the hairspring was which It would not have been after touching it many times with his screwdriver.

That is because I have not yet demagnetize it and I really wanted to have a look at the hairspring to see what condition it is in. I am new to this and do read a lot of books but experience by Doing is more important. I am still waiting for the demagnetizer and when it arrives I will give the spring a shot and see if the spring goes back to its natural shape.

[jdrichard]

I tend to use videos as well as it is very hard to describe some tasks in text. We now use videos in aerospace maintenance so the students can get a full appreciation of the task. Mark makes some amazing videos that actually gave me the courage to remove the spring and check it out. As I get better, I do like to share whatever knowledge I have picked up and pass it along. Where I have success, in technique, it is good to share...as well as where there are failures. I hope that your comment showing poor understanding and knowledge was not directed to me. I am knew at this but spend an exceptional amount of time reading. By the way, kids will not read books these days so, without videos, nothing gets passed along and we will end up with 3D Printed Electronic Watches only. My 2 Cents.

[stoli67]

Anyone managed to source new mainsprings for these? I tried a few places but no joy.

 

 

[rogart63]

U can use a mainspring for a 6309 if that is easier to find. Seiko number 401615 . 6139 have 401616. But Stefan at  schillachi61have NOS mainspring for 6139 and 6138  at ebay have them . Send me a PM and i can send you his mailadress. 

https://www.ebay.com/itm/Seiko-6138-6139-Mainspring-Genuine-Seiko-Nos/372328296603?hash=item56b07ef09b%3Ag%3AzE4AAOSwdjNZGrKi&_sacat=0&_nkw=seiko+6139+mainspring+&_from=R40&rt=nc&_trksid=m570.l1313

Edited August 14, 2018 by rogart63