Omega Pocket Watch

[StuartBaker104]

A friend asked me to take a look at a pocket watch recently which stayed in hand setting mode even with the crown pushed in.  I assumed a broken yoke spring... but actually no harm done, other than dried up really sticky oil everywhere!  Goodness knows when this movement was last serviced, but certainly not in the last 20 years I would guess.

I didn't take any photos before disassembly as it wasn't really easy to see what the problem was just by looking.  But this picture of the train bridge shows the centre wheel stuck in its bush with crusty oil

 

Unfortunately, there are also a few fingerprints and corrosion spots on the plates, which I couldn't remove during cleaning.

I found a couple of other interesting things during the disassembly.  The bridle on the mainspring has a little Omega symbol stamped on it.  Sadly, I don't think the spring is correct for the watch - it should be a double brace and hole spring, but only has the lugs to fit in the barrel slots, not the hole.  It may also be a little short, but on the basis that it must have worked once, I thought I'd clean it up and give it a whirl.

  

More problematic was that the balance staff was missing a little off one of the pivots - enough that the pivot wouldn't reach the end-stone, so I figured that had to go.  Of course,  not easy to track down a replacement balance staff for a 103 year old watch, but eBay was my friend on this occasion.

New staff on the right, and what a beautiful blued Breguet hairspring

Set in the lathe ready to turn off the hub

Hub removed so I can punch out the staff

Old staff out

Punches at the ready to rivet the new staff in to place - one domed to spread the rivet and one flat to set it.  The staff was a little loose in the balance arm, but it riveted down OK.

Finally pushing the roller table back into place

And checking the poise.  It was a little out, but there was some dirt in a couple of the screw head slots and removing that seemed to do the trick. 

Hairspring back on and ready to go

Keyless works back together and now moving freely

Barrel bridge on

Train wheels and jewels all cleaned

Train in place

One of the lovely things about old watches is the serial number popping up everywhere.  It had been scratched inside the barrel and I didn't take a photo of that. but here is the marking on the back of the pallet cock. 

and on the back of the balance cock

Quick wind and off she goes

The case is stamped EWCCo (English Watch Case Co) and is hallmarked for 1927 so is therefore just over 10 years younger than the movement.  It also has some case screw marks inside which don't line up with the Omega movement so obviously a later marriage.

And just for kicks, alongside my Omega PW from the same year.  I think I know which one John will want me to give back to him and anyway I'm still in love with those Omega hands!

 

 

Edited April 19, 2019 by StuartBaker104
Typos

[AlexeiJ1]

Great writeup.
Is there a reason you had to turn that bit down in the lathe prior to punching the staff out?
I have yet to replace a staff, although I have acquired a staking set.

Cheers

Alex

[jdrichard]

Great write up. Every watch is a different challenge. I have been making balance staffs for some time now as I love making them.


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[StuartBaker104]

@AlexeiJ1There are tools out there that allow a balance staff to be punched out without removing the hub. I’ve never tried one, but I don’t understand how they overcome the basic challenge. When the staff is fitted, it is pushed in so the balance arm sits against the hub. The diameter it sits upon protrudes ever so slightly higher than the arm, so tapping this with a domed punch causes it to spread out slightly. The flat punch sets this so the staff grips the arm like a rivet.

When replacing the staff, if the hub has been turned away the staff can be pushed out so the riveted part doesn’t  have to pass through the hole in the balance arm. Otherwise you have to push the staff out the other way and risk damaging the balance arm hole. Clearly a new balance complete is not really an option here!

@jdrichardIf only I had the time to perfect that art! Sadly I have to find time to go to work too!

[nickelsilver]

I have the punching out tools but always turn off the hub and push the staff out the top, like OP did. It's cheap insurance against distorting the balance and extra time on the poising tool.

[jdrichard]

I too cut out the staff to save the balance. Just cut out the rivet


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