# From the Watchmakers Bench - Omega 552 repair



## Guest (Jan 7, 2017)

*Omega Calibre 552 repairs and restoration*

This vintage Omega arrived with a few defects. It was last worked on by an Omega Certified Watchmaker, who's botched repair caused a lot of damage.

The owner was complaining that the stem was pulling out, here's what the keyless works and set lever looks like, a lot of swarf and brass fillings, why are there filllings?



Here is the reason for the brass fillings, check out the stem 'repair' that the Omega Watchmaker attempted to correct a worn mainplate stem bearing hole.



The reason this particular Omega watchmaker did this was because the mainplate and barrel bridge are both slightly worn and this was causing the stem to unlock from the set lever, in an attempt to prevent this from happening, he decided to add a stem extender to the existing stem, to give it a larger bearing surface and help keep it in place. Problem is that his finishing leaves a lot to be desired and instead of fixing the problem, he made it worse, the mainplate is now very worn and in much worse condition than before.

The correct fix should have been the custom fabrication of a new stem that correctly fills the worn bearing surface on the mainplate and barrel bridge.

Of course the first fix it to install a new factory Omega stem but that is not a solution, the factory stem has a very short bearing hub and if there is any wear in the mainplate this short hub allows the stem to flex resulting in the stem falling out with the set lever fully tightened, a custom stem is the only solution. This is what the OEM stem looks like when installed, compare this to my new stem later on.



*Custom stem fabrication*

First task is to thread a piece of high carbon steel rod, I thread it in the annealed state, then I harden and temper it to blue for the remainder of the machining.





Then the rod is flipped end for end and the hub which is the part that fits in the movement bearing, is machined so that it fills our worn out mainplate bearing



Then I make the inner tip - pilot pin - that fits into a small bearing in the mainplate, it's purpose is to keep the stem aligned when you pull the crown to the time setting position.



Next with the hand graver, I machine down the winding pinion shoulder and test fit the winding pinion



Next task is to make the square section that the clutch wheel, my filling rest is attached to the lathe.





Test fitting the pinion and wheel



Here is a good view of why a complete new stem was required, note how I made the stem a snug fit and that there is no longer any play or possibility of disengagement from the set lever. Compare this to the OEM stem from earlier and you can see how this stem fills the bearing while the OEM one doesn't.



A comparison, on the TOP - my custom made stem, MIDDLE - the Omega Watchmakers attempt, BOTTOM - an OEM Omega stem, not how short the bearing hub is and why it's not usable



Sometimes a factory part is not an option, due to wear on other parts of the movement, if you can custom make a replacement part, the watch can be put back in use.

Thanks for reading.

Rob


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## jnash (Dec 6, 2010)

Hi Rob, incredible work as usual, may I ask why a stem was created instead of some sort of new boss for the main plate as I know that is sometimes a fix as well and would then allow standard replacement stems in the future. Is it purely that there isn't that much space? Thanks again

Sent from my ONEPLUS A3003 using Tapatalk


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## Rotundus (May 7, 2012)

:notworthy:


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## martinzx (Aug 29, 2010)

Great work and post! many thanks :thumbsup:


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## Guest (Jan 7, 2017)

jnash said:


> Hi Rob, incredible work as usual, may I ask why a stem was created instead of some sort of new boss for the main plate as I know that is sometimes a fix as well and would then allow standard replacement stems in the future. Is it purely that there isn't that much space? Thanks again


 Thanks for the positive feedback.

Due to the design of the stem bearing where the bearing surface is divided between the mainplate and the barrel bridge, and the fact it's not a completely round bearing, but has a number of cutouts, it's not possible to machine out the existing stem bearing surface and fabricate and install a new bearing.

The only solution is to live with the worn bearing and make a stem to compensate for the wear. In a case where its' really worn out, only fix is a new mainplate, an expensive option.

If you had a mainplate where the stem bearing was only in the mainplate and a complete circle, you could enlarge the worn bearing and press home a new bearing, but in the case of most watches, the bearing is divided between the mainplate and barrel bridge, a custom stem is the only fix.


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## davidcxn (Nov 4, 2010)

Fantastic workmanship & pics, thanks for posting. :thumbsup:


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## jnash (Dec 6, 2010)

Thank you rob, I admire your technical ability, as a hobbyist I am always learning from incredible restorers such as your self , thank you for posting your work .

Sent from my ONEPLUS A3003 using Tapatalk


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## Pip (Jul 19, 2016)

Thanks for posting this; once again it's fascinating to see what Is involved and follow your steps. I had same question as jnash about just replacing the bearing!

Sent from my iPhone using Tapatalk


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## andyclient (Aug 1, 2009)

Outstanding craftsmanship and great write up as always :notworthy:


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## deano1956 (Jan 27, 2016)

good job, also good photo's and info on what's going on , I look at the photos and see nice big parts and clear pieces and work undertaken , then I realise and smile to myself that theses pieces are TINY and the work is meticulous and very delicate, and admire the craftsmanship. all this makes my first battery change today look rather pathetic but I save myself a £10 !! :laugh:

deano


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## Karrusel (Aug 13, 2016)

Excellent post again Rob. :thumbsup:

My affliction with Tourette's prevents me from taking on anything other than very 'minor' watch issues. :laugh:


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## Tazmo61 (Oct 3, 2016)

Superb post with great pictures , very educational , thanks for posting Rob .


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## Noslho (Nov 13, 2016)

Thanks again for the continued education Rob.


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## Roger the Dodger (Oct 5, 2009)

Great stuff as usual, Rob....keep 'em coming! :thumbsup:



Karrusel said:


> Excellent post again Rob. :thumbsup:
> 
> My affliction with Tourette's prevents me from taking on anything other than very 'minor' watch issues. :laugh:


 As I get older, Alan I seem to be like you....an ever increasing affliction of Tourette's, whatever job i'm doing....... :aggressive:


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## Karrusel (Aug 13, 2016)

Roger the Dodger said:


> Great stuff as usual, Rob....keep 'em coming! :thumbsup:
> 
> As I get older, Alan I seem to be like you....an ever increasing affliction of Tourette's, whatever job i'm doing....... :aggressive:


 Roger, you would think the more youthful members would treat us veterans to a day out occasionally as a distraction.....wouldn't you? :laugh:


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## Roger the Dodger (Oct 5, 2009)

Karrusel said:


> Roger, you would think the more youthful members would treat us veterans to a day out occasionally as a distraction.....wouldn't you? :laugh:


 Grea idea...where shall we say we want to go first?


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## Karrusel (Aug 13, 2016)

Roger the Dodger said:


> Grea idea...where shall we say we want to go first?


 I'd suggest Switzerland but suspect they would probably suggest the same as my offspring..................a place called Dignitas.

Have you heard of it Roger, apparently all they offer for breakfast is a bowl of cheerios! :bash:


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## Roger the Dodger (Oct 5, 2009)

.......apparently all they offer for breakfast is a bowl of cheerios! :rofl:


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## harryblakes7 (Oct 1, 2010)

Excellent job!!!


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## PC-Magician (Apr 29, 2013)

You should write a book I would certainly buy a copy.

If I remember correctly you have an engineering background and also probably very good at maths, that area I struggle with.

A great advantage when moving over to Clocks and Watch movements.

Good to know you do work like this as I never throw an old Watch away that in my mind is a sin no matter what the brand.


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