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Craftsman
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I've just finished servicing a 6309-7040 which needed a few repairs doing as well as the service. One of these repairs involved replacing the balance assembly as one of the spokes was bent and the hairspring was roached. You can see the mess the spring was in at the outer end where it passes through the curb pins and is clamped to the regulator arm. The coils were also way out of centre and it wasn't flat anymore!



As one of the spokes was bent I would imagine that some clumsy regulation had taken place and the implement that was used to move the regulator slipped and damaged the hairspring on the way to bending the balance!

Normally with a slightly damaged hairspring if you're careful you can manipulate it straight again but this was so badly damaged the watch wouldn't run in any position. Given that the balance was also damaged a replacement was in order. NOS balances for the 6309 are like hens teeth so the usual way this job is approached is to get a dress watch with a decent 6309 in and swap the balances. I've done plenty in this manner but the customer for this one wants it as accurate as it can be so a NOS balance was in order. Now the 6105 shares the same dimension balance, staff and impulse jewel as the 6309 but the hairspring is slightly different and is also terminated differently with a small stud pinned to the end. The 6309's hairsprings outer end has no stud and it doesn't have the kink that the 6105 has to allow passage through the curb pins, it has a gentle curve instead. Having said this they both oscillate at 21,600bph. I thought I'd show how a 6105 balance assembly can be converted for use in a 6309. Pictured below is a 6309 (on the left) and a 6105 balance, the differences with the hairspring are readily apparent.



What isn't so apparent is the impulse jewel is positioned under the opposite spoke to the hairsprings end on the 6309 and at 90 degrees to it on the 6105 as indicated by the arrows. Obviously for the beat error to be able to be adjusted correctly the 6105's hairspring position has to be changed. Also the stud has to be unpinned from the hairspring and the end has to be reshaped to resemble that of the 6309 and allow smooth passage between the regulators curb pins. The picture below shows the stud and pin once they were removed, next to one that is still fitted to a hairspring.



There's no trick to removing the stud, it just takes a steady hand to press the pin out. Once it's off you can work to reshape the end of the hairspring, again this takes a steady hand and a couple of pairs of fine tweezers, but be mindful of the fact that the hairspring has to remain absolutely flat once adjusted. If you introduce kinks in the vertical plane it will never run correctly! Once you're happy with the spring press it back on to the balance in the new position, 180 degrees opposite the impulse jewel. Once attached you can refit the balance to the regulator, centralise the hairspring so it has an even coil all the way around and ensure it passes cleanly through the middle of the curb pins. Refit the balance assembly and see how it performs.

This was after half a wind and adjustment of the beat error.



The proof of the pudding is how it performs in different positions, DU, DD, CU, CD etc and I'm pleased to say no further adjustment of the spring was necessary, it gained about 10spd in each postion, the only thing that changed was the beat error widened to 0.3ms in the CD position which is to be expected.

Another repair this needed was the with the train bridge. Lack of lubrication had allowed the third wheel pinion to wear away the bearing in the plate, it ended up slotted as you can see from the picture.



It should look like this.



The third wheels pinion had no wear at all so I imagine that must have been replaced, I can't see the benefit of replacing it without replacing the bearing though! I just substituted the bridge for a spare I had which was in tip top condition.



It goes to show that even Seikos don't last forever if they aren't looked after occasionally!
 

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Great post and excellent pics, thanks.
I noticed on the last pic - the barrel arbor bush looks different on both bridges - one looks thinner than the other, it could be the lighting though :)
 

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An amazing write up with great pics (even I could understand it and that's saying something!) As a novice, posts like this are a real eye opener and give a good insight into the world in which you ply your craft.
It amazes me the dexterity and patience you must have to do this sort of work. I really am in awe of your skills my 'hamfistedness' precludes me from even trying - which is probably best all round!
I can see just how distorted that initial hair spring is but straightening out the kinks in a 6105 spring to make it work doesn't sound easy!?!
Seriously impressive work.
To even get it running is good but to get it to under 10 spd in many positions if fabulous for a vintage watch like this!
 

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An amazing write up with great pics (even I could understand it and that's saying something!) As a novice, posts like this are a real eye opener and give a good insight into the world in which you ply your craft.
It amazes me the dexterity and patience you must have to do this sort of work. I really am in awe of your skills my 'hamfistedness' precludes me from even trying - which is probably best all round!
I can see just how distorted that initial hair spring is but straightening out the kinks in a 6105 spring to make it work doesn't sound easy!?!
Seriously impressive work.
To even get it running is good but to get it to under 10 spd in many positions if fabulous for a vintage watch like this!
My exact sentiments. Amazing work and write-up.

Thanks Thorien for saving me some time !
 

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Great write up!

I too like to service my 6309 movement myself , which is +50s a day. Where can I find more steps by steps guide like these?
Any recommend for a demagnetizer?



Sent from my iPhone using Tapatalk
 
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