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Craftsman
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Discussion Starter · #1 ·
After a self inflicted suspension of watch activities it has been a relief this week to get back to the watch bench, albeit in a new room, in a new house in a new country (we moved house on the 20th April moving from England to Wales).

The first watch to be worked on was a very nice gmt World Time sporting the 6217 movement.



the timegrapher reading was very erratic



clearly indicating a service was in order.

The movement was in very good condition, except for this



the watch had suffered the all too common barrel arbor wear, both to the mainplate and the barrel bridge. At some point this wear had been 'corrected' by punching around the barrel bridge bush with a round nosed stake, pushing metal towards the centre in an attempt to close the bush. This is a very imprecise method, in fact when I removed the bridge it lifted the barrel with it and I had to carefully pry it loose.

After some discussions with the owner about what to do, I offered to jewel the mainplate and barrel bridge. On the 61xx and 63xx this is very straightforward and there are jewels available now from several sources. But, on the 6217 there are no jewels available that fit the barrel arbor.

My offer was based on having measured the barrel arbor of the 6217 and finding it wider at both ends (and therefore too big to fit in the available jewels). The lower (mainplate) arbor:



compared to the 61xx



and the upper (barrel bridge) 6217 arbor



compared to the 61xx arbor



Having started to do quite a bit with my Lorch lathe, I felt that it should be quite possible to turn both ends down to a diameter matching the 61xx barrel arbor and thus to fit the available jewels.

I practiced first on a scrap 61xx arbor - seeing how easy it was to machine a flat surface, and then how easy it was to polish this surface. Next I tried a 6217 arbor, using the same technique. I could fib and say it went perfectly, but I took too much off the lower end, and while it would fit the jewel, it would be too loose (rather like a worn bush - defeating the purpose of jeweling!!).

Attempt #2 was good. So, with a 6217 arbor that fitted the jewels, I then had to jewel the movement. The mainplate was straightforward - the same process as the 61xx mainplate.





But, on the barrel bridge things got a bit more complicated. SEIKO obviously realised that brass bushes for the barrel arbor would be subject to high wear, so on movements after the 6217 they fitted a steel bush to the barrel bridge. Jeweling the barrel bridge involves pushing this steel bush out, and replacing it with the identically sized jewel.

The 6217 barrel bridge has no steel bush - I therefore needed to broach out the brass bridge to fit the jewel - 2.5mm in diameter. I thought this would be easy, until I realised that my Seitz jeweling set comes with a 229 (i.e. 2.29mm) reamer and a 259 reamer. I checked my Boley set and found the same sizes.

Hmmmmm.

Not to be defeated there followed multiple iterations of broaching using the 259 reamer, first on one side of the bridge and then repeating on the other side - doing this under a loupe so that I could see exactly how much metal I was removing.

After quite a while of heart in mouth work I got this





and no breakages!!

With this done, I was able to clean the movement



and rebuild it.





and then test it!!



and 8 hours later



much more stable and a nice strong amplitude.
 

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Administrator
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Quality work Simon.

Good to know your move went well and your now settled.
 

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Really nice work, and I chuckled at the “heart in mouth” part. I can claim arthritis as a reason why I would never try such a thing, but the real reasons are cowardice and lack of talent ;-)
 

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Truly terrific work Simon. I hope that you are getting settled in your new place.


Sent from my iPhone using Tapatalk
 

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That looks fantastic!

Can I ask, as the reaming bits are slightly tapered, were you able to use just a lower portion of the 259 bit from both sides of the bridge to achieve your 2.5mm goal? If so was this trial and error or did you measure and mark the bit in some way?

Thanks

Gavin
 

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Hi Simon,

Hope all is well with you and your family and that all of you are enjoying your new surroundings.. Thanks again for sharing the detailed write up and pic's.
Michael
 

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Craftsman
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Discussion Starter · #10 ·
That looks fantastic!

Can I ask, as the reaming bits are slightly tapered, were you able to use just a lower portion of the 259 bit from both sides of the bridge to achieve your 2.5mm goal? If so was this trial and error or did you measure and mark the bit in some way?

Thanks

Gavin
it was ultimately trial, with hopefully no error. I marked the bit for depth by seeing how far it went into a 6139 bridge (with steel bush removed). As you say, as the reamer bits are tapered I knew that if I only broached from one side I would have a hole that was either the correct size at the beginning but got smaller as the jewel was pressed in (which I'm certain would have resulted in it cracking), or was too large at the beginning which was likely to end in a scrapped bridge (once the hole is too big - even a hairs width - its game over).

I ended up taking tiny amounts of brass off - shavings really as I got closer to what I hoped would work. Obviously this is not entirely accurate (in terms of absolute position and circumference of the hole) but I knew it was going to be better than where the bridge started.

I did consider using the steel bush (from a 6139 bridge) first, to set the hole, as this would not crack and instead push any undersize brass out of the way but I felt that I'd only do this if the first jewel I pressed home cracked.
 

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Craftsman
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Simon - Welcome back. I always learn something new from your posts. As they always say, nothing ventured, nothing gained. Amazing out of the box thinking. So nice to see a good results on a watch that will run well for years. Thanks for taking the time to post and show pictures.
 

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Congrats on the new place and excellent work as always.
 

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hi simon,

i'm so glad to hear you've moved and are comfortable again. that's
a big job.

these watches are very small jobs, but the word perspicacity always
comes to mind when i see a job like this done as beautifully as it is.

congrats on all,

peter
 
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