Cal 711, service and repair summary

I haven’t told him yet, but this all started with @ChrisN’s cal 561 detailed disassembly post. We’ve been talking for a while and he has provided many tips and support, but I never explicitly blamed it on him, so here you are Chris, it’s all your fault!

I’ve always been interested in the technical part, more than checking if the dot is over the 90 or how many red lines a watch has. I had been reading and trying to understand the differences in different calibers, and that post (and the subsequent one on BHI) pushed me over the edge, so I started buying some tools, a “scrap” 267 to play with, and signed up for a BHI workshop next July (may sign up for the whole course, still deciding).

After playing with that 267 for a bit I decided it was time to do an actual service on a watch, so I tried to fine one with some minor fault or even just not keeping time that I could try to fix. I found a cal 711 that was described as having an erratic seconds hand. Thanks to the huge amount of time I spend here and the very interesting posts from people like @ChrisN and @Archer I knew what that issue was and I thought I could fix it. I also wanted Omega’s only ultra-thin movement so I jumped in and got it for very cheap.



When it showed up it indeed had the erratic seconds hand, but the case was perfect, super sharp, some signs of use but no scratches, it was definitely used as a dress watch. The dial has some damage around the edges and the paint on some of the markers has fallen off, but overall still pretty nice. But as I picked it up and started winding and setting I heard a rattling. Moved it around and sure enough the oscillating weight was rattling inside. This made me very sad because it was not mentioned in the description and could have been a much bigger repair than I’m capable of (or equipped for).

The seller said it kept good time but my timing machine disagreed, strongly, but I was less worried about that, the hairspring looked nice so let’s see after getting it cleaned and oiled.

So I open it up and start to investigate, and quickly enough I find that it’s the rotor post that’s moving around, and the good news is that the post is attached to the automatic winding module with two screws, and the screws had become loose during transport – the seller said it was fine when he shipped it and it seemed genuine, also because the rotor and case back had no scraping marks at all.

You can see the post support and two screws at the top of the automatic module here:



Given that this potentially showstopping (for me) issue was sorted out I started actually stripping it down. After removing the automatic module above the culprit for the erratic seconds hand is immediately visible: a mangled friction spring, probably due to someone fitting the seconds hand directly using this spring as support without protection.



The spring is also an aftermarked replacement: the shape is different from the one in Omega’s parts list. Cousins had one of these in stock so I ordered it without even trying to fix up this one. Here you can see the difference between the one that was installed and the new correct one:



Further disassembly gave more confirmation that the previous service wasn’t of the highest standard, with lots of oil spread around.

(please excuse the dodgy photography and random white balance, this is the first time I do “studio” type things, I usually shoot handheld at ƒ/8 on 400 ISO film 😀)



Fortunately the general condition of the movement was very good, with no worn parts and few scratches (and I’m confident I din’t add more).

I also replaced the pallet fork bridge, but purely for aesthetic reasons: the one that was installed appeared to be a genuine Omega part but somehow it had its finish removed and it looked bad so I (miraculously) found one on eBay and replaced it to make it look nicer. Very odd, I wonder why that has been done.

You can also see more of the oil on the escape wheel jewel here.



No more surprises after this and I completed the disassembly (I didn’t disassemble the reversing wheel and the indirect minutes driving wheel, that’s for next time):



After a bath I started reassembly and the most frustrating and nerve wracking part was definitely this little guy: the bottom cap jewel spring is not held in place by anything once you lift it, there is just a notch that keeps it there when it’s under tension, but as soon that’s released it just slips out. It took many, many tries with cool-down breaks between them to get it in, maybe there’s a trick to do it easily but I haven’t found it.



Cleaned it all and finally reassembled, it was very rewarding to see it ticking again.



On the timing machine the performance is not perfect but fully satisfactory for my first job: amplitude is ~280º in both horizontal and vertical position; rate delta is about 30s on six positions; beat error is high at over 2ms but that will be for next time; timekeeping on the wrist is good for wearing and power reserve is around 40 hours.

When I first received it I wondered how the case could be so perfect and the dial so scratched. Someone with more experience would have noticed immediately but it took me a minute: the dial screws were missing, so the dial was only kept there by the hands, meaning that it was shaking inside the case and rubbing on the edges, causing those marks all around it.

In conclusion it has been a very interesting experience, I learned a lot and after workgin on this I picked up the 267 again and it’s huge, it’s much easier to work on those now 😀

Thanks again to @ChrisN for direct email support and tips and to @Archer and all other knownledgeable members I learned from.

Bonus halfway assembly picture because it’s a nice one and better shows how pretty it is after cleaning.

Oddly, I just happened to be on the forum when an alert popped up that I had been tagged...

I am mightily impressed that you managed to sort all of this out as it's hardly the simplest movement at all. On the other hand, there's nothing like wearing something you've rebuilt yourself and that's a huge achievement😉 You'll learn how to strip the reversing wheel (winding wheel) later and as we say where I am and even @Tritium might say, you learn "poco a poco".

I'd forgotten my 561 post until you mentioned it and I won't look at it now in case it's not of a standard I'd now like to write 🤦 but, I'm really pleased if it inspired you a little.

Oh, you'll work a way for the Incablocs that will suddenly make them seem easy. Wait till you see the parts in that winding wheel....

It's been a pleasure to pass on some of the knowledge I've acquired (in large part thanks to Al) so, I look forward to the next instalment!

Cheers, Chris

Nice to see some new guy working on his watch! Nice job!

I struggled too on some jumpy inca springs! For me it was with Omega 625 and 620. The secret? Practice! It is like refitting the stud on a hairspring: the first times you really think only Superman and guys like Archer and Chris - who I did not know at that time but that is the spirit - can do the job! Then you succeed and afterwards it is not so hard.

Keep going!

You're absolutely right, Francois. There's no substitute for time at the bench and all of this becomes more second nature as you build the hours. As you're well aware, and I don't think this comes over very well in the photos, these parts are very small and dealing with them presents many problems.

You see enough movements with lots of scratches around the Incabloc springs to know that a lot of people seem to struggle with them but, once you have a system, they are no problem. At the beginning though...
flipping difficult🙁

Cheers, Chris

That works in Italian too 😀

The 561 post was very helpful, there aren't many around with as much detail.

I’m trying to find others to practice but I’ve been very lucky with this one, some pretty bad ones are selling for mad prices.

I’ve seen people using pegwood to hold parts while handling them so even with the stress I was able to avoid scratches.

Peg wood is the watchmaker's friend, professional or amateur!

Nice work. Glad to see someone jumping in, and hope that my posts have helped.

Couple of things - I know you likely didn't want to remove the cannon pinion for the large driving wheel, but to properly clean the jewel and oil it, that really is a must. Not sure what your plans are to revisit this watch, but running I like this for an extended period of time will likely result I damage. If you need help in techniques for removing and replacing that CP, just as ad I'm sure one of us will help you.

For the beat error, this one is easy - the watch has a moveable stud carrier so adjusting the beat error can be done in a just seconds on the timing machine - of course you will have to adjust the rate again after that, but again it won't take long.

And yes peg wood has it's place, but I don't use it for holding parts down - it tends to flake a bit so I use something that doesn't leave a mark but also won't have the potential to cause contamination. It's a piece of acrylic rod that can be used for many things - I have been working on a post about a few basics for a couple of weeks now and will elaborate on that when I post it.

Keep up the good work!

Cheers, Al

Good info about pegwood Al, thanks! I must confess I use it - clean new piece of course - to hold parts in position while screwing them. I am looking forward to seeing your post!

Thank you Al, your posts have definitely helped. In this case for example I knew what was wrong with the seconds hand and how not to mess up the new friction spring because you described it in a post.

About this I do have a question: to fit the seconds hand I rigged up a support with pith wood and a small piece of steel (I remember you mentioning you use an old mainspring), but that was not ideal, are there specific tools or techniques for this case?

And while I don't use this watch very often, I do plan to rework it to address the center pinion (I just ordered the presto tool, that I also need for a cal 285) and hopefully do a better oiling job too. Oiling is not easy and it's also hard to tell if you've done it right.

Bit difficult when I don't know what specific tools you use for hand fitting, but I'll just show you what I use and you can adapt from there to your situation. So for hand fitting, I use a press like this:



It uses different diameter runners for pressing on different hands:



You will note that the movement is in a holder - I refer to these as dial side movement holders. Over time you tend to gather a lot of these, and they are sometimes not cheap - they can easily be $400+ for one holder depending on the complexity. But often for simple 3-hand watches, just buying by ligne size allows you to use the same holder for many different movements. BTW the one for the Cal. 711 is only $160 or so, so that's not bad.

The red movement holder has a support in it that you can adjust for height - as you can see here each movement holder has it's own design and sometimes more than one support depending on what movement it's for:



The support is there to give backing to either the jewel or pinion of the wheel that the hand is being pressed onto. So in modern watches that don't use this indirect seconds method, it's usually up against a jewel. In a watch like this, it would be up against the friction spring, and without protecting that spring it can get damaged by the pinion by the force of pressing the hand on. So I put a piece of old mainspring in place between the spring and the pinion:



So if you don't have something to support the pinion that can get up in the movement far enough to touch the pinion, then you won't get much support as you press the hands on. Some advocate putting the automatic winding on for some movements and using that as backing, but that's not the "proper" accepted method, and often the space between the spring and the bridge closest to it is too far to provide proper support, and the spring gets bent when pressing the hand on - this leads to stuttering hands.


If this was easy everyone would do it. Oiling is a subject that we could go on about forever as there are many opinions about what is the right amount and type of oil for a particular spot. I do hope to provide some tips on that subject at some point as well.

Note that when you remove something that is pressed on, like that CP or a drive wheel, it has to be pressed back on. For that I typically use the Horia jewelling tool - I use it more for pressing on drive wheels and cannon pinions than I do for jewel work sometimes.









So if you don't have something to use for this, give some thought on how to press the parts back on.

Cheers, Al