Omega 351 main plate pin stuck

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Eric J

·Mar 17, 2022

Hello all,

I have restored a nice two tone Omega cal 351 bumper watch case ref 2577-11. When I went to case the movement it was bouncing around inside and it turns out the 351 has a main plate pin to secure half of the movement. Sure enough, the pin has been sheared off and no longer retains the movement. Unfortunately it is half stuck in the movement. I sent off for the only Omega 330 part #1022 I could find online (hopefully it is actually in stock), but I still need to get the half pin out of the watch.

How do I do this - it seems pretty stuck, simply plucking at it with tweezers hasn't worked?

Thanks

 

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Dan S

·Mar 17, 2022

I can't really see how it is retained, but can you just tap it out with a punch? Hold it in a vise with protected jaws.

 

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JimInOz

·Mar 17, 2022·Melbourne Australia

If the pin is steel, it could be removed by soaking in a saturated solution of alum.
You would beed to strip the plate and only immerse the portion holding the pin.

A number of posts by @Archer describe this method.

 

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studeb

·Mar 17, 2022

It looks like it is parallel to the main plate. If so i would agree with Dan S, a punch should get it out, or at least loose enough to get a grip with something to pull it out.

 

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Canuck

·Mar 17, 2022

I had the same problem with a bumper Omega. I stripped the pillar plate of all the steel components and soaked the pillar plate in goldsmith’s “pickling” solution (couldn’t locate alum). Within two days, problem solved.

 

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Dan S

·Mar 17, 2022

I would suggest listening to @JimInOz and @Canuck over me. 📖

 

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Eric J

·Mar 17, 2022

Did not expect such a response, I have been searching a decent amount for information on these 330 series pins and nothing much turns up.

I am going to give it a shot with a punch of sorts. The pin is smaller in diameter than most screws on this movement - hopefully I can get it loose. I am going to need something with a little more texture at the points to actually grip the pin, the tweezers have no friction. Maybe a small pair of pliers?

 

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Dan S

·Mar 17, 2022

Eric J

Did not expect such a response, I have been searching a decent amount for information on these 330 series pins and nothing much turns up.

I am going to give it a shot with a punch of sorts. The pin is smaller in diameter than most screws on this movement - hopefully I can get it loose. I am going to need something with a little more texture at the points to actually grip the pin, the tweezers have no friction. Maybe a small pair of pliers?

If you are going to try a punch, try one that is slightly smaller in diameter than the pin and punch it out completely using controlled firm taps from a small hammer. Grabbing it and pulling it out will be harder; static friction is more easily overcome using impacts.

Again, this advice is just based on my general experience with small mechanical parts, mostly associated with scientific instruments. I have little direct experience with this type of repair on watch movements. In your place, I would be listening to the watchmakers.

 

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Eric J

·Mar 18, 2022

the main plate pin has shipped - can't believe it was actually in stock somewhere in the UK.

I do have a parts movement with a good main plate - so if something really goes wrong (the pin is super stuck) I can swap the entire movement over to a secondary main plate. I am trying to avoid re-servicing the watch as I am already 2 hairsprings (risky ebay buy) and 1 balance cock into the movement. This 351 movement has proven to be more tedious than the 500 series I generally stick to.

 

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watchyouwant

·Mar 19, 2022

Every correct diameter stainless rod cut to size will do the job also..... Had to replace a few over the years.

 

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Eric J

·Apr 30, 2022

I ended up swapping the mainplates and installing the pin - there is still a small amount of movement even after slightly bending the single case clamp. I don't know if there will ever be a way to completely stop the rattle, but it is much improved over not having the pin.