145.008 Chronostop 865

pldlnr · May 15, 2021

Hello,

After admiring for many years, I recently purchased a 145.008 Chonostop Caliber 865. It is a project as I knew it had a broken mainspring and needed service. Its in very nice original watch in beautiful cosmetic condition. However, it arrived with a destroyed hairspring that was not discernible in the pictures.

I am now in the hunt for a replacement. In my search it seems that a balance complete is the likely path, but I would be open to a complete assembly (balance, hairspring, bridge).

I haven’t had any luck with the usual suppliers or eBay. I am a hobbyist and have no professional accounts or affiliations. Any advice on used parts suppliers or other resources for the 860/861/865 family of parts?

Thanks in advance.

Paul

amcclell · May 15, 2021

Would an 861 balance assembly fit this movement? I was under the impression that the Lemania chronostop movement was derived from the 861. If Archer sees this, he will be able to tell you.

Is this a DIY project, or is your watchmaker unable to obtain the part?

pldlnr · May 15, 2021

amcclell
Would an 861 balance assembly fit this movement? I was under the impression that the Lemania chronostop movement was derived from the 861. If Archer sees this, he will be able to tell you.

Is this a DIY project, or is your watchmaker unable to obtain the part?

Yes, this is my personal watch and I am an amateur/hobby watchmaker. My dad was a watchmaker and horology instructor for many decades in the Seattle area and I spent years working for him. But, I am just a hobby collector at this point.

I believe you are correct, the 860/861/865 all use the same balance.

amcclell · May 15, 2021

While not cheap, I would think if worse comes to worse, you can turn to a watchmaker that has an Omega parts account.

ChrisN · May 15, 2021

Do you have a picture of the hairspring? These are often not as bad to fix as they initially look and a complete balance will be expensive. If it is recoverable, that will be far cheaper.

Cheers, Chris

Archer · May 15, 2021

pldlnr
I believe you are correct, the 860/861/865 all use the same balance.

Yes and no. These are all the same base movement, but there were different balance assemblies used over the life of these movements.

If you replace like for like, they would work fine, but you need to be sure you get the same balance with the same configuration.

pldlnr · Jun 30, 2021

Just a follow up. After weeks of searching, I located a complete balance (balance wheel and hairspring). I was able to replace it and get the watch running well.

One complication - the hairspring had a round end on it instead of the triangular end. I was told that this was an update made over time for this series of calibers. This created the need of careful fitting to get the angle of the hairspring correct once the screw was tightened holding the spring end in the balance cock.

The good news is that the watch is running very well. It was a a challenge to source all of the parts without access to Omega, but I was eventually able to find OE crystal, mainspring, balance complete, and case gasket. I love the watch and am surprised by its overall presence. An underrated watch in my opinion.

la_lusigne · Jun 30, 2021

Well done 👍
That’s one of the cleanest example I’ve seen of this reference

timecube · Jun 30, 2021

pldlnr
Just a follow up. After weeks of searching, I located a complete balance (balance wheel and hairspring). I was able to replace it and get the watch running well.

One complication - the hairspring had a round end on it instead of the triangular end. I was told that this was an update made over time for this series of calibers. This created the need of careful fitting to get the angle of the hairspring correct once the screw was tightened holding the spring end in the balance cock.

The good news is that the watch is running very well. It was a a challenge to source all of the parts without access to Omega, but I was eventually able to find OE crystal, mainspring, balance complete, and case gasket. I love the watch and am surprised by its overall presence. An underrated watch in my opinion.

An absolute beauty!

.
I believe this is the first time I have felt that over a chronometer. Not usually a fan.

145.008 Chronostop 865

pldlnr

amcclell

pldlnr

amcclell

ChrisN

Archer

pldlnr

la_lusigne

timecube

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