Omega Chronostop „UFO“ disassembly

[handwound]

Hi guys, 

i just bought this Omega Chronostop and I‘m not quite sure how to get out the movement. 

I know that it is a front loader, so normally you could pull out the crown (split stem) and pop out the crystal with air pressure. 
Problems:

1. because of the case-shape I can’t use a modified presto tool, like Mark suggested in his video and I can’t remove the crown by hand only.

2. if I can remove the crown, how can I seal the chrono-pusher, so I get enough pressure to pop out the crystal? Will Rodico do the job?

 

Thanks!

[jdm]

55 minutes ago, handwound said:

I know that it is a front loader, so normally you could pull out the crown (split stem) and pop out the crystal with air pressure. 
Problems:
1. because of the case-shape I can’t use a modified presto tool, like Mark suggested in his video and I can’t remove the crown by hand only.

Many  people use a modified nail clipper. You may have to file it extensively to get a good grip.

55 minutes ago, handwound said:

2. if I can remove the crown, how can I seal the chrono-pusher, so I get enough pressure to pop out the crystal? Will Rodico do the job?

Even if an air pump is an excellent method to open front loaders, there is no guarantee it will work, either for issues with perfectly sealing the pendant or other tubes (rodico would have zero effect), or just a strong hold by the crystal gasket. In these case the solution is to use a crystal wrench, Omega made a set of these, which now are very expensive when they can be found used, you can also look at a Seiko tool which is is more reasonably priced and easier to find.

[handwound]

Thanks for your reply. 

Is there any difference between the crystal wrench you are mentioning and a crystal lift?

[jdm]

14 minutes ago, handwound said:

 Is there any difference between the crystal wrench you are mentioning and a crystal lift?

Big difference. A crystal lift is a claw type tool that works by reducing diameter of an plastic (acrylic) crystal in order to remove or refit it with the minimum force. The same principle can also be applied using a crystal press and proper dies.

A crystal  wrench is made to positively grab around an uncompressible crystal in order to remove it, out helped by some twisting. Then the crystal is refit with a crystal press. 

[JohnR725]

1 hour ago, handwound said:

I know that it is a front loader,

Out of curiosity how do you know it's a front loader?

[handwound]

Just now, JohnR725 said:

Out of curiosity how do you know it's a front loader?

The case is similar to the Omega Dynamic. It doesn't have a caseback, instead a ring that holds the bracelet in place. 

[JohnR725]

I don't suppose Omega put any helpful writing on the back of the case? Sometimes they might put which tool you're supposed to use so you have a clue of how you're supposed to open it.

 

[handwound]

3 minutes ago, JohnR725 said:

I don't suppose Omega put any helpful writing on the back of the case? Sometimes they might put which tool you're supposed to use so you have a clue of how you're supposed to open it.

 

Actually it says tool 107, but I wanted to check if there is a way to open it, without spending a lot of money on a tool that you will only use for this particular watch. 

[JohnR725]

I had a suspicion because this discussion is come up before and knowing the tool might help to find the other discussion.

Or you might find a link like this where you get a clue what the tool looks like. Or perhaps even a bonus of somebody disassembling a watch like yours.

http://old-omegas.com/tool107.html

 

[handwound]

1 minute ago, JohnR725 said:

I had a suspicion because this discussion is come up before and knowing the tool might help to find the other discussion.

Or you might find a link like this where you get a clue what the tool looks like. Or perhaps even a bonus of somebody disassembling a watch like yours.

http://old-omegas.com/tool107.html

 

Thanks for the link, I already came across the same one   I found this tool for sale but over 70€ for something that I will probalby use one time is quite a lot. At least for me. In the article it is said, that you could also use a crystal lift, but as I understood from @jdm it shouldn't be used with this type of crystal (armored crystal) because it is not compressible like regular acrylic crystals are. 

So should I try to use the crystal lift to remove it or not? The crystal is original, so I really don't want to crack it. 

[JohnR725]

You can use a crystal lift with an armored ring but? The problem is you have limited compression range and if you go too far you will have pieces of a crystal. That's why their special tool grabs a little bit differently but their tools still compresses the crystal.

 

 

[jdm]

44 minutes ago, handwound said:

I found this tool for sale but over 70€ for something that I will probalby use one time is quite a lot.

Personally I would get it, it's a quality item and not a terrible price in horology. Then if in need one can always easily resell it. I once have seen a complete set on Y! Japan auction, I thought I could have got it for an affordable price, well it was not so, it sold for an high price really.

[Nucejoe]

Do we know what caliber is inside and its diameter? 

Backplate looks removable to me or is my stigmatism getting worse,

[handwound]

3 minutes ago, Nucejoe said:

Do we know what caliber is inside and its diameter? 

Backplate looks removable to me or is my stigmatism getting worse,

Caliber 920, ranfft lists it with a diameter of 27mm.

I‘m really sure there is no way to open it from the back.

[Nucejoe]

I see the seam between the backplate and case, however narrow the gap, I insert a safety razor blade into the seam, work your way all around to widen the gap, next use a tool thicker than razor, keep on until you can use a knife blade. 

[jdm]

27 minutes ago, Nucejoe said:

I see the seam between the backplate and case, however narrow the gap, I insert a safety razor blade into the seam, work your way all around to widen the gap, next use a tool thicker than razor, keep on until you can use a knife blade. 

There is no seam, what are you seeing is the undercut where threading ends. This is a genuine monocoque / front loader case.

[jdm]

If someone is still confused about what a monocoque (single piece) case is, let me quote from an article about this interesting piece, even if doesn't add much to what the OP wrote above.

il convient également de noter l’apparition, en 1970, d’une version spéciale destinée au marché italien et produit dans la famille Genève. Il s’agit de la référence 146.012, utilisant le calibre 920 à quantième, et représentant une sorte de transition avec les modèles Dynamic créés à la même époque. Ce modèle, dessiné et fabriqué par Fontana exclusivement pour l’agent italien De Marchi, reprend en effet le système de boîte monocoque dit « Uniloc », avec fixation du bracelet selon le modèle Dynamic (anneau dévissable à l’arrière de la montre).

https://omegang.wordpress.com/2018/08/10/1966-145-007-omega-seamaster-chronostop/

If your French got a bit rusty, translation is just a click away, or soak it in Coke

[JohnR725]

7 hours ago, Nucejoe said:

Backplate looks removable to me

 

11 hours ago, handwound said:

tool 107,

It would've been helpful to everyone right at the very beginning if the words on the back had been mentioned. Notice the reference to tool 107? That's your clue that the back is not removable no matter what it may or may not look like. Usually but not always watch companies that are doing something different will tell you that like if you need a special tool to open the watch.

[Klassiker]

Get the correct tool. If you can get one for 70 EUR, that's the same as a good-quality claw, which is the wrong tool anyway and will likely damage the surface of the acrylic at the very least.

[handwound]

Bought the tool, I will post some pictures when it arrived. Thanks for all the answers.  

[handwound]

so here it is, the Omega Tool 107...

The crystal has a groove the tool grabs under, then it compresses the crystal and pulls it out of the case. 

 

Here you can see the monocoque / one piece case design:

 

I was happy to see that the movement is absolutely flawless. The case already looked quite good, but the movement really is the icing on the cake.

 

Edited April 7, 2021 by handwound
edit

[LittleWatchShop]

Not sure why I clicked on this thread, because I don't have an Omega (that I know of).  But when I got to the end and saw the tool, the light bulb went on.  I have seen this!  Yup, my Dad must have needed it somewhere along the way and now I have it.  LOL...now I need an Omega to open up!

[JohnR725]

4 hours ago, LittleWatchShop said:

Dad must have needed it somewhere along the way and now I have it. 

The other thing he may be remembering is it probably wasn't all by itself it might've been in a box. So more I've seen a box of them. It's like all the other weird specialty tools lurking in a watchmakers bench absolutely must have for one particular watch. Then later generations ponder what's this for?

[LittleWatchShop]

4 hours ago, JohnR725 said:

other weird specialty tools

I have a bunch of back wrenches with patterns that I guess are unique to a particular watch.  Some of them are labeled for accutrons.