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Centre wheel sideshake

PeterS
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PeterS WRT Addict

PeterS

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I’m going to have to ream out the mainplate and the bridge and put jewels in.
This is a centre wheel and the pivots are 0.64/0.75mm.
I see one of my options are for the 0.64 a jewel with a hole 0.66, that’s 0.02mm tolerance. I think that should be OK?
The 0.75 my options are 0.76 hole which is only 0.01mm tolerance and 0.78 hole which is 0.03mm tolerance. I’m guessing that the 0.01 could be too tight for a centre wheel and I’d be better off with the 0.03 tolerance?

I’m also thinking of jewelling the barrel but I’m unsure of the tolerances. Plus one side of the barrel arbour is 1.68mm and I could not find any Seitz jewels with that diameter hole.

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PeterS WRT Addict

PeterS

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No, it’s not short, the 0.75 is the side the protrudes through the mainplate and the cannon pinion goes on the end.
In this case I can go pivot 0.75 / jewel hole 0.76 and the other side that’s short and goes to the bridge is 0.64 and the closest jewel I can get is 0.66.
Would you be happy with that yourself?

I should add, sweep seconds goes through the short side 0.64/0.66

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nickelsilver Distinguished Member

nickelsilver

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By short I mean the distance from pivot to pivot- on watches with center wheel under the barrel this can be very short, and sideshake at the pivots will be amplified at the end of the cannon pinion. In that case I would really look for 0.01mm clearance/shake. If your center wheel is "normal", i.e. above the barrel, the pivot to pivot (shoulder to shoulder) distance should be long enough that the extra 0.01mm shouldn't matter- in either case it should run fine. In the "short" case you might wonder why the minute hand is twice as far from the dial on one side compared to the other!

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PeterS WRT Addict

PeterS

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Ah, from pivot to pivot, now I understand.
Thank you for the explanation, I can order the jewels now.

I presume the same applies to barrel sideshake? 0.01?
I’m thinking of jewelling the barrel too but I’m struggling to find a jewel for 1.68mm diameter arbour. I looked just about everywhere and I cannot find a Seitz jewel of that diameter.

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