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351 movement cannon pinion problem

J
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I am relatively new to watchmaking so I'm sure this question will show up my inexperience...........

I have nearly finished the restoration of an early 1950's 'bumper' and it has been a joy to work with such astonishing craftsmanship. Unfortunately I mislaid the cannon pinion during cleaning and so have purchased another. It was sold as 'used' and should be part 351-1218. I realise that we are looking for an interference fit on the centre wheel shaft and note that the new cannon pinion has a professional looking crimp on both sides of the middle of it to provide this 'interference', but unfortunately the replacement cannon pinion is too tight to get more than half way down the centre wheel shaft. So my question is whether Omega matched an individual centre wheels to a cannon pinion in house to make a matched set? in which case presumably I need to ream it to a sliding fit (how?) and then re-crimp.Or have I been sold the wrong part?

Photo attached and any guidance would be much appreciated.
 
Omega 351 cannon pinion.jpg
sheepdoll
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The parts list usually shows these together. Canon pinions listed separate, but not center wheels.

They come in different heights. That can often be the only difference between calibers. The dial/calendar mostly determines the height.

I recently got an assortment of bumper parts. Canon pinions seem to often be lost. I have found loose fitting more common that tight fitting. I have a staking attachment for tightening them.

Online sellers often do not really check the subtle differences. Parts in estate lots often get mixed together. There is also the risk of someone dumping broken parts. Once got an assortment with half a cannon pinion vertical. Tips are also often missing or damaged. Makes for much of the challenge.

After practicing on the A Schild and Landeron watches, I had forgotten how much a delight Omega watches are to work on. It is real easy to get addicted to parts assortments.
 
Archer
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Could be the wrong part - really no way to tell when you are shipped a loose part like that, so you are at the mercy of the seller on that front. The crimp doesn't look particularly aggressive or anything.

Cannon pinions and center wheels are sold separately, so there is no factory "matching" done. However it's not unusual for new parts to need some tweaking.

You can open up the ID of the cannon pinion using either cutting or smoothing broaches - both if you have them. Just work it a little at a time until you get the right fit. Don't forget to apply a little grease to the recessed area on the center wheel, just to keep the cannon pinion from seizing on the center wheel over time.
 
J
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Thank you both for taking the time to respond, much appreciated.

I'm learning from you that cannon pinion height is varied and my replacement one measures 2.2mm. Of course I don't know what it should be although I see that some sellers advertise at 2.5mm, so I have test fitted it to the original hour wheel to see what end clearance I'm left with. Photo attached and I would be grateful to hear back from those with more experience than me on whether it looks right?
If the height is OK, then I will keep the cannon pinion and do as Archer suggests by investing in a set of broaches. Any recommendations on sets/brands or has it to be Bergeon?
 
IMG_20240627_122230_MP~2.jpg
Archer
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J JerryM
Thank you both for taking the time to respond, much appreciated.

I'm learning from you that cannon pinion height is varied and my replacement one measures 2.2mm. Of course I don't know what it should be although I see that some sellers advertise at 2.5mm, so I have test fitted it to the original hour wheel to see what end clearance I'm left with. Photo attached and I would be grateful to hear back from those with more experience than me on whether it looks right?
If the height is OK, then I will keep the cannon pinion and do as Archer suggests by investing in a set of broaches. Any recommendations on sets/brands or has it to be Bergeon?

That looks correct. If you think about it, if the minute hand is fully pressed onto the cannon pinion, it should be just above the hour hand, which is usually pressed flush with the top of the hour wheel.
 
DON
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There's 3 heights

Caliber 350 - 2 mm

351, 352 and 354 - 2.2 mm

353 and 355 - Calendar - 2.9 mm

I use Bergeon - Set 4338 and if needed. Smaller set for hands
 
sheepdoll
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Of all things forgotton. Look what came in the mail today from last weeks binge.

IMG_4542.png


I had purchaced two 332 assortments over the last few weeks. Really 332 plates, which share parts with the 351. Of course the seconds bit is different. What I really wanted was the case clamps. I keep getting 330 clamps when I needed 332 clamps.

It is interesting how the watch breeding program works. Parts I am desparate for take weeks to arrive. Then a 99cent start NR bulk estate auction comes up and all of a sudden there is a new crop of parts.

So the package did come with the cannon pin mounted. I guess this is the base caliber height as the package is only marked 351 1224.
 
J
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Archer - thank you for confirming that it looks like I do indeed have the correct cannon pinion and also for explaining why.
Don - Good info, so thank you. I'll be getting the Bergeon set you recommend.
Sheepdoll - useful to know that you have the centre wheel/pinion set and I'll be in touch if the plan to ease mine out doesn't work out.

I'm really pleased to learn that there's good experience and freely given advice out there. I'll post some pics of the finished watch soon.
 
X350 XJR
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J JerryM
I'm really pleased to learn that there's good experience and freely given advice out there.

No place better than OF in my opinion.

And I'll note that the moderators all work for free as do the techs, thanks @Trev, @dsio that keep this wonderful place running behind the scenes.
Edited:
 
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