I recently bought this really nice gold plated Seamaster Cosmic Automatic. I have just got it back from a £320 service and am a little concerned about its poor timekeeping. It loses an hour and a half overnight. I have not had a vintage automatic Omega before so I don't know much about what you can expect from them nor do I know how to give it the initial wind to charge the power reserve. Can anyone advise me? Thanks!

 

You should be able to turn the crown (probably clockwise) about 50 or so turns to get it charged up. After that, daily wear should keep it going, depending on hos active you are.

Losing a hour and a half is not normal. Might be worth taking back for a chat, or finding another watch maker.

 

There are plenty of discussions about how "accurate" a vintage watch can be, but if it has just been serviced it should be much closer gain/lose 30seconds than 30 minutes!

Btw, nice watch.

 

An automatic wind watch should be fully wound manually, before being put into service. Thereafter, is should be worn almost every day for 12 to 16 hours on the wrist of an active person. If left off the wrist for up to 36 hours, ideally, it should run fine for that length of time. One mistake made by many folks who have grown accustomed to quartz watches over the decades is that they feel an automatic should function like a quartz, and perform the same way when exposed to the same wearing patterns. Wear it as an automatic should be worn, and if performance still suffers, return it to the shop.

 

Many thanks for this.

Following your advice I have tried turning the crown clockwise and I can hear the mechanism inside making all the right winding sounds. However it seems quite stiff and I'm worried that attempting 50 turns might damage the watch - am I being too timid?!

 

Turn until you feel resistance and it stops. If it's had a new crown, it's often stiff to wind for a few weeks.

 

It's an automatic.

They have an "unbreakable"mainspring.
Meaning......you can wind as long as you like but when the spring has fully coiled around its centre post, the tail of the spring will slide around the outside of the spring container.

That is unlike a fully "manual wind" spring that is attached to the outside edge of the spring container, you wind these until you feel a definite stop which means the spring is stretched between the centre post (in a coil) and the tail is held at the side or wall of the spring container.

If you keep winding one of these (by using gorilla fingers) you either tear the tail of the spring away from the side of the container, or bust the little tooth hole in the centre part of the spring.

So.......................................

Wind until you feel a change in resistance or a "slipping" feel. Your auto should then be fully charged.

 

Many thanks - that's really useful

 

Jim's right about being able to wind it as much as you like without damage - an automatic mainspring has a slipping bridle at one end, so it will slide rather than stop. This is the "clutch" that many people on watch forums refer to, but that word makes it sound much more complicated than it really is.

I agree that the watch should be wound fully before putting it on, and if it's still losing significant time, it needs to be looked at as that kind of variation is unacceptable in a freshly serviced watch.

One clarification on the term "unbreakable mainspring" is that this actually refers to the material the spring is made of rather than it being manual or automatic, and this term goes back a few decades. Initially mainsprings were made of blued steel, and although it was the best available at the time it had some drawbacks. Blued steel mainsprings become set over time (this means they loose their initial shape), they rust, and they are also quite prone to breakage. They are brittle, and often you will open a mainspring barrel and find something like this:



When they are set, they lose power and are smaller than they were originally, so you can see a blued steel spring that is set on my bench here after it came out of the Waltham pocket watch:



When companies came out with alloy springs that not only maintained their shape very well, but were much more difficult to break, they dubbed them "unbreakable." This is obviously not the case, as I still see plenty of broken alloy mainsprings, but compared to what they were using it must have seemed like they were unbreakable at the time. These are some alloy mainsprings from my mainspring stash, and as you can see they are made by different companies and all have "unbreakable" or something similar in their listed attributes:



All of these are manual winding springs by the way, so none of them have a slipping bridle. So in addition to the springs being less fragile, less prone to setting, and less likely to rust, the alloys used allow modern springs have a different shape. You can see that shape illustrated in the top left package in the photo above, so the spring is not just a spiral, but an S shape. Here is a modern alloy spring from a Speedmaster Pro (Cal. 1861) and you can see two things here. One is that it's shaped like an S, and the second is it wasn't unbreakable, because it's broken:



The S shaped spring helps deliver more consistent power to the movement as the spring winds down, which helps keep the timekeeping better when the watch is getting close to the end of it's wind. I never use blued steel springs, and if I find one in a watch I will always replace it. Most watchmakers do the same, but I have received watches that were freshly serviced where someone didn't replace the spring - not acceptable work IMO. Often an alloy spring of the same dimensions is a little stronger than the steel version, so you have to be careful with selection when replacing them.

Note that the Omega in question posted by the OP was made at a time when all springs were alloy. I would think that you would have to go back to the early 50's or even late 40's for blued steel springs in Omegas. I rarely see them in Omega watches, except for some 30 mm manual winds...

Cheers, Al

 

Wow thanks!