Omega Calibre 268 Service Walkthrough

[VWatchie]

Disassembly pictures and assembly pictures in my following posts if you don’t wish to read the following.

For some unknown reason I never omit to mention to my IT students (.NET) that I have a passion for watches, that this passion is my analogous counterweight to my digital interests, and that there are a lot of similarities. Often, I am pleasantly surprised to learn that in almost every class there seems to be at least one or two students who share my passion for watches.

The watch in the following walkthrough, an early 1960s Omega SeaMaster housing a calibre 268, belongs to a former student of mine who trusted it to me for a service. So, I take this opportunity to thank you Mattias for your trust!

The base movement of the calibre 268 (pdf parts list here) is the calibre 260 (pdf parts list here). It is a textbook example of what a manually wound mechanical watch is all about, and if it were not comparatively expensive it would be the perfect candidate for the beginning learner. Anyway, if you happen to have an Omega calibre 260-based watch in your drawer, you don’t mind breaking or losing something that will need to be replaced, and you wish to take the watchrepairlessons.com courses, then this movement will be just the thing. It is almost identical in design to the Unitas calibre 6498 used in the courses.

I should mention that this walkthrough is not a tutorial. I have made it for my personal use and enjoyment. It will show what I do, what parts I lubricate, and in what order, but it will not show how I do it or describe the cleaning process. That said, the walkthrough includes some tips to facilitate the work. For example, I had some difficulty getting the stem out until I realised it wasn’t enough to loosen the setting lever screw but that it also needed to be depressed. So, I took a note of that and included it in this walkthrough.

There are many ways to service and repair a watch, but I usually follow the practices as taught at watchrepairlessons.com, and it has worked very well for me. I am in no way affiliated with watchrepairlessons.com but to me it has been the best, most enjoyable, and most affordable way to get started with servicing and repairing watches, so I wholeheartedly recommend it.

I was somewhat hesitant make this walkthrough. After all, it offers no “horological wonders” to uncover. As mentioned, it’s a textbook example of a mechanical watch and @Mark has already made an excellent and possibly more useful walkthrough here: Omega 268 Service And De-Rust. However, it was such a beautiful movement that I just could not resist the challenge to try to take some nice macro images of it and its parts. And hand on heart, I enjoy creating and sharing these walkthroughs (I guess it is the teacher in me). However, this time around I’ve tried to minimize the number of pictures but still make it clear what is going on.

I’m getting long winded, but just one more thing. To me this watch and movement pretty much constitutes the epitome of aesthetics and function. I can admire its exterior and interior from any angle endlessly, and the fit and finish of the parts are outstanding (definitely a notch up, or two, or three from the Russian movements that I adore and usually work on). When assembling the movement, it feels like the parts are magically drawn together. It is quite clear that this watch was designed to be appreciated and enjoyed not just by its owner but by the watchmaker servicing it.

So, without further ado, here goes…
 

Edited November 18, 2020 by VWatchie
Now better illustrated

[VWatchie]

 

[VWatchie]

[Tudor]

I still say Omega makes the most beautiful (mass produced) movements.

Nice walk through!

[Poljot]

Fantastic walk through, thank you!

Have you measured the ID of the mainspring barrel? What was it? 11mm or 11.5mm?

Have you measured the old mainspring to see if it matches the new GR4186 ?

Could you please upload a photo showing the shape of the old mainspring? Was it S-shaped?

I am asking these questions based on my experience with 30mm Omega watches , when cataloguing information did not match the actual original parts. The ID was off, the thickness of mainsprings was also of (same 1.5mm height though).

And lastly, about GR mainsprings?: you were lucky to get a nice and clean GR4186 mainspring, which according to GR is supplied "teflon-like dry lubricant" coated. Several GR mainsprings that I received did not look that shiny. In fact, they were coated with anything but "teflon-like dry" lubricant. Perhaps an old stock? Thus I had to clean it and lubricate with 8200 grease.

Did you apply White Luminous compound on the Hour  Minute hands?

[VWatchie]

@Poljot I like you member name. Here's a beautiful Poljot I serviced a year or so ago!

No, I didn't measure the ID of the mainspring barrel or the old mainspring. I simply trusted the GR4186 and fortunately it seems to be working well (as stated by the owner). However, as I fell in in love with this type of watch and movement I picked one up on Swedish local eBay (tradera.se) and it's in the pipe for an overhaul. As I have several other projects and ideas going I'm not sure when it is going to be, but I'll try to remember to measure and take some photos then.

Anyway, the old MS was S-shaped, but it was obvious the movement had been serviced a couple of times before my service of it, so I don't think it was the original spring. My guess is that it had probably been serviced last two to three decades before my service it.

Yes, I've heard other WR-talkers mention that GR springs sometimes are dud , but I've been lucky so far.

Yes, I did apply the white lume as the original lume simply fell out of the hands as soon as I touched them, and white was the only color at hand. I guess a "retro"-color would have been better...

[Poljot]

3 hours ago, VWatchie said:

@Poljot I like you member name. Here's a beautiful Poljot I serviced a year or so ago!

 

Thank you! Poljot 2616.2H was the first watch I repaired and serviced several years ago when I got myself involved into this wonderful hobby. It's worth mentioning that I was the one who screwed up that watch many years ago :-). Now it works like new. I also got myself deep into 30mm Omegas. Simply love them. I find that due to age, 75-85 years, many of these watches look vintagely-tired (perhaps a new word), but the movements inside still look like they were manufactured recently. I did some calculations to find a suitable mainspring replacement for older Tavannes / Cyma & Omega watches when I realized that someone improvised (used whatever mainspring was available) many years ago. Then i compared my measurements and calculations with GR catalogue and was unpleasantly surprised to see that GR catalogue mainspring barrel ID was often wrong by 0.5mm-1.00mm, which makes difference. I find that GR would show 12.5mm when in fact three watches of the same caliber on my desk would be 11.5mm ID. Thus, 0.155 or 0.15 mainspring would be too strong for these watches. But like you, I trusted GR catalogue and ordered one mainspring for 30 caliber Omega. That mainspring was way too strong, and it was not very clean (we see lots of things under microscope, right? ). When i removed it for cleaning (a brand new mainspring), shape-wise it looked exactly as my 41year old one... Far from being S-shaped. And it was stronger than needed (even winding did not feel right - too mach resistance). I simply riveted a new bridle / hook to the old mainspring and put it back. I asked about lume as at some point i wanted to apply it on Omega 30 hands and was looking for a suitable colour. Perhaps Yellow (light green)?. It is always a dilemma with vintage watches To Lume, or Not To Lume?! For now i decided to leave it as-is. I am afraid that that lume will look out of place. What do you think?

[markr]

love the dial.  Tint your loom so that it looks aged. Not hard to do.

[Poljot]

I love it too. Do not see such dials with these type of hands very often. 1935 according to its serial number (unless database is not accurate). Do you know if such dials ever had lume applied on the dial itself (1-12 numbers), or just on Hour and Minute hands?

[markr]

Just the hands.

[markr]

You can also use a white lume and dip them in black coffee when they are dry to age them.

[Poljot]

No milk, no sugar?

I was looking at another option: Yellow (Light Green) - (Bergeon 5680.J.07)

Should be a perfect match with the centre of the dial.

[Poljot]

Searching the Internet for a reasonably priced Geiger counter to see if previous stuff was radioactive.

[VWatchie]

On 11/20/2020 at 4:01 PM, Poljot said:

That mainspring was way too strong, and it was not very clean (we see lots of things under microscope, right? )

So that is pretty bad. Mainsprings are generally problematic and mainspring winders even more so. Mainsprings are what has given me the most headache during the few years I've been doing this. Are you sure you're not mistaking the dirt for the dry lube which I believe tends to form white specks that look like dust? I could be wrong about that!

 

On 11/20/2020 at 4:01 PM, Poljot said:

For now i decided to leave it as-is. I am afraid that that lume will look out of place. What do you think?

Beautiful watch! I agree, especially as the dial doesn't have any lume dots.

[Poljot]

8 hours ago, VWatchie said:

So that is pretty bad. Mainsprings are generally problematic and mainspring winders even more so. Mainsprings are what has given me the most headache during the few years I've been doing this. Are you sure you're not mistaking the dirt for the dry lube which I believe tends to form white specks that look like dust? I could be wrong about that!

 

Beautiful watch! I agree, especially as the dial doesn't have any lume dots.

It's hit and miss. Some GR mainsprings come nice and shiny / clean, some in questionable condition. By questionable I mean black dots on the surface, dry / old looking packaging, which appears to be very fragile and not air-tight. I can clean them and install - not a problem as long as they are not "tired". How come that a new spring looks identical or worse in shape than the 40-year old one? That's why i was curious to see your old mainspring from 268 calibre. After reading your comment about GR mainsprings being  supplied prelubed, i will cut down on lubrication. However, i never overoiled any mainsprings in the past. A tiny drop (not even a drop) of 8200 in three locations 120 degrees apart, and some closer to the arbour. I also put a tiny-tiny drop on the inside surface of the barrel's top cover.

 

My biggest challenge is finding proper cataloguing information about the mainsprings for vintage watches, including Omegas, Tavannes.  GR shows some conflicting / wrong info about Strength, and ID of the barrels. Marshall's catalogue is no better, unless i am missing something (would not be the first time ).

And about lume: why would Omega apply lume on the Hands Only? Was it common practice for Omega?

[VWatchie]

On 11/22/2020 at 6:13 PM, Poljot said:

And about lume: why would Omega apply lume on the Hands Only

I'm not so sure, it could be that the hour numerals where made luminescent but has faded. Just speculating!

[Poljot]

2 hours ago, VWatchie said:

I'm not so sure, it could be that the hour numerals where made luminescent but has faded. Just speculating!

I also thought so as some numerals do have a hint of what used to be lume, but others are perfectly clean. It could be luminescent that fell off the minute and hour hands, or they were in fact lumed... No one seems o know for sure as there was no Internet in 1930s... people did not snap gazillions of pictures of their watches and did not post them on-line

[Poljot]

On 11/20/2020 at 5:53 AM, VWatchie said:

@Poljot I like you member name. Here's a beautiful Poljot I serviced a year or so ago!

No, I didn't measure the ID of the mainspring barrel or the old mainspring. I simply trusted the GR4186 and fortunately it seems to be working well (as stated by the owner). However, as I fell in in love with this type of watch and movement I picked one up on Swedish local eBay (tradera.se) and it's in the pipe for an overhaul. As I have several other projects and ideas going I'm not sure when it is going to be, but I'll try to remember to measure and take some photos then.

Anyway, the old MS was S-shaped, but it was obvious the movement had been serviced a couple of times before my service of it, so I don't think it was the original spring. My guess is that it had probably been serviced last two to three decades before my service it.

Looking at the Barrel Lid photo above in your post, the old mainspring was either warp slightly or of incorrect height. I like your presentation very much. I have very similar if not identical approach / standards for cleaning. However, I prefer using mineral lubricants on older calibers: 8200, 8141, 8000, etc and Seiko silicone grease on O-rings and gaskets. Do you leave the Main Plate Jewel Setting in place (held by one tiny screw)? 

[VWatchie]

@Poljot

I just dismantled my 2nd Omega SeaMaster calibre 268 and here's the mainspring:

On 12/5/2020 at 3:56 PM, Poljot said:

I prefer using mineral lubricants on older calibers: 8200, 8141, 8000, etc

That's interesting. Is it because you wish to be more consistent with the lubricants available at the time these watches were made, or for some other reasons?

On 12/5/2020 at 3:56 PM, Poljot said:

Do you leave the Main Plate Jewel Setting in place (held by one tiny screw)?

I leave it in. Never saw any reason to remove it, but I must say I've scratched my head over the design. Why not integrated on the main plate?

[Poljot]

4 hours ago, VWatchie said:

@Poljot

I just dismantled my 2nd Omega SeaMaster calibre 268 and here's the mainspring:

 

That's interesting. Is it because you wish to be more consistent with the lubricants available at the time these watches were made, or for some other reasons?

I leave it in. Never saw any reason to remove it, but I must say I've scratched my head over the design. Why not integrated on the main plate?

Thank you for taking measurements to answer my previous questions. It appears that your existing mainspring is in excellent shape. It fits GR4186 description as it's somewhat challenging to take accurate measurements without a micrometer: 0.12mm could be easily 0.125mm. If it's not too late, please take ID measurement of the mainspring barrel. I am curious if it's 11mm or 11.5mm ID.

You are correct in your assumption - mineral oils are great, more consistent with what was available at the time watches were design and manufactured. Mineral oils stay in place, provide excellent lubricity and as long as cleaning and oiling was done properly, you have nothing to worry about for many-many years.

I always remove those plates. Why? Two reasons:

- I usually see such design on "helpless" watches that people bring to me. I feel "obligated" to do proper cleaning

- i bought many nice screwdrivers - I MUST use them

Why such design? It was probably less expensive.

[VWatchie]

7 hours ago, Poljot said:

If it's not too late, please take ID measurement of the mainspring barrel. I am curious if it's 11mm or 11.5mm ID.

Sure, no problem! Think I'll have some time for this movement tomorrow so I'll measure it then. 

7 hours ago, Poljot said:

It fits GR4186 description as it's somewhat challenging to take accurate measurements without a micrometer: 0.12mm could be easily 0.125mm.

I have a Bergon micrometre precise down to 1/100 of a millimeter that I use for jewels, but I trust my German high quality caliper, so I believe 0.12 is pretty much spot on (give or take +/- 2/100)

[Poljot]

26 minutes ago, VWatchie said:

 I trust my German high quality caliper, so I believe 0.12 is pretty much spot on (give or take +/- 2/100

Sehr gut!

This means that someone fitted slightly weaker mainspring in the past: 0.12mm Vs 0.125mm as per GR catalogue, or Ranfft.de's Mainspring  description 1.50 x 0.135mm.

[VWatchie]

On 12/12/2020 at 4:24 PM, Poljot said:

If it's not too late, please take ID measurement of the mainspring barrel. I am curious if it's 11mm or 11.5mm ID.

So, I measured the ID (inner diameter) of  the mainspring barrel to 11.45 mm. However, as I didn't want to push the steel jaws of my calipers to hard into the barrel walls, I guess in reality it's more likely 11.50 mm.

BTW, do you know what alloy the movement is made of? Color-wise It looks like a mix of gold, copper, and brass.

[Poljot]

1 hour ago, VWatchie said:

So, I measured the ID (inner diameter) of  the mainspring barrel to 11.45 mm. However, as I didn't want to push the steel jaws of my calipers to hard into the barrel walls, I guess in reality it's more likely 11.50 mm.

BTW, do you know what alloy the movement is made of? Color-wise It looks like a mix of gold, copper, and brass.

Well, well, well. Here we go again: 11.5mm Vs 11.0mm. Aren't you glad that you do NOT need a new mainspring for this watch? Because if you did, there would be a dilemma : GR4186 or GR4208, or perhaps something else..

I don't know exact chemical composition, but I could bet (small amount) that there is no gold in it. Perhaps brass, or some other copper based alloy, plated with .. copper?

[Marc]

10 hours ago, Poljot said:

plated with .. copper?

http://members.iinet.net.au/~fotoplot/rgold/rgold.html