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hanski

Adventures in Servicing a Gen Omega Seamaster 1120 Movement

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hanski

After having serviced 3 genuine vintage Tudor movements, a couple Sellita’s, and numerous Asian clones, I’ve decided to embark on the journey to service a genuine Omega 1120 for a Seamaster. 

Received the watch, looks good albeit clearly worn and loved. 

VWWrkU.jpg

I give it a full wind, set the date, set the time, and...nothing. It’s not ticking. Some more winding, some gentle shakes...nothing. I flip it upside down...there it goes. Hmm, this doesn’t bode well. But I’ll reserve judgement until it’s been torn down and cleaned.

VWeGTR.jpg

On to removing the bracelet, caseback, and dust cover. 
VWewCg.jpg

Looks pretty clean except the stem is fully rusted and the movement ring is rusted in to place. I hope not to discover anything bad when I get the dial off. 

Off comes the automatic works and rotor together since the rotor screws are on the underside of the automatic works. 

VWel3a.jpg

Now to remove the movement, take off the hands, and dismount the dial. It takes a bit of careful effort but the rusted movement ring releases. Hands are set to be stacked, protective Mylar cover over the dial to protect dial, Saran Wrap over hands to protect finish on hands. I like to use the pry bars in lieu of the hand removing tool, I have more control. 

VWeSEG.jpg
VWegGy.jpg

Next I flip the movement back over and remove the balance, gear train c0ck, and barrel bridge. 

VWedU6.jpg

VWeYTq.jpg

VWeq40.jpg

VWeOGF.jpg

VWe3Er.jpg

Back to the top side. Thankfully no further rust or corrosion has presented itself. Off comes the date wheel, calendar works, wheels, pinions, and finish up with the keyless works. 

VWe5Uo.jpg

VWeaYI.jpg

VWeB4L.jpg

Main plate stripped. Automatic works and barrel bridge stripped down. Everything is neatly organized and ready for a four stage ultrasonic cleaning and rinse. And then it’ll all come back together with a bit of oil. 

VWkZPK.jpg

Since the balance wheel, pinion, and jewels look to be in fine shape I hope the lack of consistent movement is simply grime and age. 

Stay tuned. 

@FoxWilde

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fatarms

Good luck, my friend.  You have bigger balls than I do when it comes to gen movements.

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Theviking

Great work @mzinski

And thank you for documenting it. 

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FoxWilde

;D 

so exciting

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BM284

This is fantastic - I can live through my ‘want to be’ watchsmithing vicariously though your threads! Looking forward to the re-assembling of the movement :thumbsup: 

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GingerApple

Good work, thanks for sharing. Subscribed!

What I cannot work out is how you can do all is this so easily, yet you didn't know how to get that rotor off the other week. Is that because you've always worked on Gens before and you're just getting used to the sneaky, fake screws, glued-on method of the reps?

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hanski
5 hours ago, TomatoheadFred said:

What I cannot work out is how you can do all is this so easily, yet you didn't know how to get that rotor off the other week. Is that because you've always worked on Gens before and you're just getting used to the sneaky, fake screws, glued-on method of the reps?

Ha! Right?! 

I’ve found that gen movements are much easier to work on compared with reps, clones, and oddball assemblies because they are better constructed, more thoroughly documented, and don’t use tricks to make them look what they aren’t. And then there’s me still learning - I don’t know what I don’t know. Having worked predominantly on ETA’s, I’ve become accustomed to screwed on rotors (topside and underside). That other Omega chrono movement taught me rotors can have special screws that require a special tool - because why not make something more complicated, right? 

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GenTLe

I've gone now through many different services, from Seiko to Miyota, all the ETA clones used in reps and 7750s too.

Still I'd be very afraid to put my hands into a gen movement from another person's watch... Even if, like in this case, that's nothing else than a basic 2892 Eta.

Consider the possibility to change the mainspring as this may be set (you'll check once removed it from the barrel).

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hanski

Cleaned and ready for reassembly - mostly. 

After four ultrasonic bathes (1 cleaner and 3 rinses) all the parts were heat dried and organized, inspected, and prepared for reassembly. Also decided to demagnetized for good measure. 

Vzm8wU.jpg

Balance wheel and bridge got a One Dip bath instead. 

Upon inspecting the balance wheel I noticed the Hairspring had a bit of a kink and was touching. Maybe this explains some of the issues it was having earlier.

VzmwrD.jpg

If you look closely you can see the pin kinks in towards the center and is crooked. 

Anyways, I think most normal people would opt to buy a new balance wheel for $50. Not me! I decided to attempt to reshape the Hairspring. 

No easy feat, I will admit. First the Hairspring must be removed from the wheel - a pair of pry bars work well. It’s very similar to removing a hand set but smaller and more fragile. This was done without issue. 

Next on to reshaping the Hairspring. Using two pair of tweezers, one must incrementally, patiently, and carefully grab the spring where it is out of shape and basically massage it back to position. To confirm my reshaping I would lay the Hairspring centered on the bridge, frequently. 

Fast forward about 60 minutes and I have a center, flat, and well shaped Hairspring. Yay! 
VzmPRh.jpg

Last step is to press the Hairspring collar back on to the balance wheel. Pro tip, remember to mark the orientation of the spring before removing so it can be replaced correctly. Well, I wish I were ending this story with a pretty picture of a balance wheel complete...but I’m not. In pressing the collar something moved and pinched the spring. I don’t think I’m going to be able to reshape it this time. 

Lesson learned, just buy the balance wheel complete and install it! 

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Nikosaldente

I love watching these types of adventures!

It sucks that the hair hairspring got pinched while trying to put it back, but at least you managed to massage it back to shape!

Those 60 minutes add to your experience time...

Looking forward to seeing the rest!

Thanks for sharing!

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hanski

While I’m waiting on some parts, good progress was made in the lubricating and reassembly of the movement. On order is a new balance wheel complete, stem, and crown. 

VbIhHT.jpg

Barrel bridge with integrated click comes together nicely. 
VbIjeA.jpg

Installed on to the main plate with the drive train. 
VbILDQ.jpg

Keyless works installed using the old stem. 
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Pallet fork back on. Tested for distribution to the fork, flicks back and forth nicely. 
VbI4yX.jpg

Automatic works. 
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Rotor screwed back on. Notice this one is screwed in from the underside. When doing anything to this movement, the whole automatic works needs to come off with the rotor attached. Not particularly convenient. 
VbIAks.jpg

Date wheel, date jump, and pinnions installed. 

Look forward to getting the parts and regulating the movement. 

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hanski

New ETA chronograph grade balance Complete arrived. Looks pretty! 

VyQNbF.jpg

Simple installation. I chose to install the balance wheel and balance bridge before connecting them together. This allow me to properly align the parts and free up hands to make the connection. 
VyQijr.jpg

Movement full reassembled. 
VyQTMI.jpg

Dial and hand set reinstalled. 
VyQhAo.jpg

Re-cased. 
VyQjlL.jpg

Final step is to regulate on a full wind and test the timing over the next couple days. I was able to bring the beat error to 0.0ms and face up timing to +3sec. Pretty good. But I didn’t continue because the amplitude was very low - 150-175. Not a good sign for the mainspring. Unfortunately (not because I don’t like him but because it costs money) it appears @GenTLe was correct. I am ordering a new mainspring to install. 

Almost there. 

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GenTLe

Actually that new hairspring looks a bit too bent, are you sure it is ok? Every time I touched those little bastards I ended up into loosing a HUGE amount of time trying to get a proper amplitude...

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porschespeedster

Just wanted to say this is a VERY cool thread. Cheers and good luck.

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hanski
13 minutes ago, GenTLe said:

Actually that new hairspring looks a bit too bent, are you sure it is ok? Every time I touched those little bastards I ended up into loosing a HUGE amount of time trying to get a proper amplitude...

The new one came pre-shaped to accommodate the spring stud and regulator arms. So nicely shaped that it slipped right into the regulator arms effortlessly - with some balance springs I've had to move the spring into position. 

But now that you've brought it up, I'm going to carefully inspect it again. Thanks! 

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Phizzy

I still find it staggering when you see all those tiny parts laid out that somehow when all properly assembled, they become a beating mechanical heart....great work, I really wouldn't have the patience, but most of all, i've got fat hands.

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GenTLe
The new one came pre-shaped to accommodate the spring stud and regulator arms. So nicely shaped that it slipped right into the regulator arms effortlessly - with some balance springs I've had to move the spring into position. 
But now that you've brought it up, I'm going to carefully inspect it again. Thanks! 
If so then simply try to replace the mainspring and if the amplitude goes back to normality you'll be fine :)

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hanski

Mainspring arrived - simple enough to swap it out. Gave it a full wind and put on the timegrapher.......viola! 

+2sec, 0.0ms beat error, and amplitude up to normal. 

In addition to the mainspring, the new stem and crown arrived. Another easy swap. 

Project complete! Simply a delight to work on a gen watch like this. 

VCThpq.jpg


VCTdd6.jpg


VCTHn0.jpg


VCTOrF.jpg


VCT3wr.jpg

 

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GenTLe

Good job mate! :) 

Now, next step: take out the movement and repolish the case and bracelet :p

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CollieWobbles

:clap:

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ShovelnTC

Great work, thanks for taking the time to document it for our entertainment.

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BadApple

Not for the feint hearted - now this is a level I aspire to but will never achieve. 

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FoxWilde

Two-tones. Old vs. new!

sound job @mzinski :)

3744-D37-C-2-DFF-446-A-878-E-D166-F7330-
38-E76-F79-E690-40-F8-BF82-6785-FE096530
4589-C7-E6-604-A-4653-B8-E1-ADB33-E711-C

 

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Viking95

Nice

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Watchgrocer

Good job. Well done mate.:christmas1:

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