Reply With QuoteGreat stuff. I just love these rebuild stories. What you did with the pallet fork and stone is really tricky and difficult to get right. So well done. I have a 50/50 win rate with hairsprings that are deformed, there not easy to fix.
I've been servicing a non running 6146-8010 Grand seiko today and a few issues surfaced that I haven't tackled before. On the strip down I found the centre seconds wheel was gummed up with old lube inside the minute wheel and this was preventing he movement from turning freely (all the other degraded lube didn't help either). I also noticed the diafix spring for the dial side of the escape wheel was loose. On further inspection I found there was no end cap in there at all! You can see where the spring and end cap should normally be here.
You can see the two diashock and two diafix sets of jewels, chatons and caps in the picture, but only one diafix end cap.
This would cause the escape wheel to have far to much end shake and it probably wouldn't have run very well anyway, even if the lube was fresh. Luckily it's a standard size and I have some spares. When I went to dismantle the going train upon inspecting the pallet forks engagement with the escape wheel I notice the pallet jewel was sticking up at an angle, this is a critical part and should be dead flat in line with the fork. The watch would never have run properly like that, it was just about engaging the escape wheel.
I think when the watch was reassembled last time and the escape wheel end cap was omitted, the end shake was so much that due to a shock, the escape wheel moved down, came back up under the end stone and it bent it upwards. These end stones are usually held in place with shellac, obviously not this one.
How it should sit
And how it is
I've seen this a couple of times before, in fact I saw a similar pallet fork and end stone on a 6139 I serviced just last week. My usual fix is just to replace the pallet fork, however with this being a 36,000bph, 6146 calibre, spares are unobtainable. I've had a look at all the parts houses and there's nothing listed for the 6146. That's nothing at all, never mind a pallet fork! The only thing I can do is re-glue the stone into the fork. I've spent a pleasant couple of hours removing the old shellac and truing up the end stone so it looked like this.
As I don't have a spirit lamp, hot plate and shellac which is the old school way of doing things I've glued it back in place with some two part epoxy. You only get one attempt at the epoxy method, where with shellac you can reheat and re adjust the end stone if it's in the wrong position. Luckily the end stone was quite tight in the fork so I could set it, replace it carefully and check it operated correctly before gluing. After a couple of unsuccessful attempts I got it working properly, so I gingerly removed it and epoxied the stone in place. I did hope it hadn't moved without me noticing as I removed it.
This is the first time I've actually had to repair a loose end stone, as I've said I'd normally just replace it but with the lack of any spares that wasn't an option. I let it set overnight and reassembled the movement this morning and the timegrapher trace was all over the place! I thought it had to be the end stone not in the correct position, but under closer examination the hairspring was bent which allowed it to catch on the balance cock when it was dial up. I removed the balance wheel from the cock and re formed the spring as best I could, re assembled and it's a success! It's ticking away nicely at 36,000bph and just needs to go on test for a few days to fine tune the regulation.
Great stuff. I just love these rebuild stories. What you did with the pallet fork and stone is really tricky and difficult to get right. So well done. I have a 50/50 win rate with hairsprings that are deformed, there not easy to fix.
Hairspring correction isn't my favourite task I must admit, and when it's on something where a replacement isn't an option even less so.
Nice job! Could you shine some light on the pre and post amplitude of the balance? Repositioning a pallet stone can have a mayor impact on amplitude.
Just curious how you determined the right position of the stone.
Cheers,
Men
The watch was a non runner when it arrived so there is no pre service figure I'm afraid. Post service it's at about 200 degrees on a full wind, this is slightly down (about 40 degrees) on previous high beat 61xx calibre Seikos I've serviced so it's possible the end stone isn't in the correct position, but the trace on the timegrapher is beautifully steady so I doubt that's the case. If an end stone is not right it's instantly apparent on a timegrapher as the side with the problem will leave a ragged trace. It's also possible that a lower amplitude is due to more wear in this movement than others I've done - there certainly looked have been more wear in evidence than usual. With ordinary (6309/6105/6217/7005 etc) vintage Seiko movements an amplitude of over 200 degrees is doing very well so it's not really a concern to me. The main problem with servicing these high beat GS's and divers is the mainspring barrel is sealed and spares haven't been available for a very long time. The barrel has "Do Not Open" printed on it, it really should have "Can't Open"! Consequently the power is always compromised by not having a clean and lubed mainspring and barrel which obviously has a negative effect on the amplitude. The barrel is actually flanged over the lid, to open you'd have to cut or grind back the flange, but then you wouldn't be able to seal it back up.
A common "fix" for a broken mainspring on a high beat 61xx calibre is to fit a 6309/6105 barrel and spring which has the same arbor dimensions and barrel teeth, but then this will affect the deliverable power as the springs have quite different dimensions. Still, it's much better than having a non running watch! :)
Last edited by Thewatchbloke; 2nd July 2014 at 01:14. Reason: typo!
And to answer your question about how I positioned the stone, it was quite a tight fit in the pallet fork so I positioned it, replaced the pallet fork and bridge then checked the locking/unlocking of the escape wheel. After a couple of attempts it seemed to be doing what it was meant to do so I carefully removed it and epoxied it in place. I did think when I removed it for the last time that if it moves without me noticing I'm sunk, as with epoxy you only get the one attempt at it.
Interesting! I`ve never tried re-fixing pallet stones, I`ve always sourced a replacement pallet fork.
The lack of new mainspring/barrel assemblies is frustrating. I`ve had the same issue with old Omegas; a new spring doesn`t help much if the spring barrel's worn. The result is a loss of amplitude and poor power reserve........but we can`t 'magic' new parts out of thin air so it's a case of making the best of what's available.
Thanks for posting.
Paul
It sounds like that movement was a mess. It is impressive that you got it working again.
Why not get some shellac and a spirit lamp? They aren't particularly expensive.
Best wishes,
Bob
Guess what I've got on order Bob?
The only reason for using the epoxy was time constraints, I needed to get the job finished, I know how to mix epoxy, and I've read plenty of articles where it's been tried and proven in the past. With the shellac and spirit lamp approach I didn't really have the time to wait for the equipment to arrive and practice the techniques needed for a successful job.
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