Omega vintage bumper repair - newbie tearing hair out...need help

[GPrideaux]

It's possible but unlikely that several different pallets all have an identical problem. The fact that swapping pallets did nothing to resolve the problem is evidence that the problem is not in the pallet itself.

End shake is determined by the distance between mainplate jewel and bridge/cock jewel. If that is the problem, there may* be nothing wrong with the pallet so swapping in a different pallet should not be expected to resolve it.

* There may, of course, but other issues with the pallet that will become more apparent once the end shake is addressed.

On 1/9/2025 at 4:45 AM, tb1982 said:

Most of these donor watches will "run for a few seconds or minutes then stop".

You can't assume that they all have the same problem. Even if they exhibit the same symptoms they're unlikely to all have the same issue. It's not hard to think of four or five different scenarios that would result in the watch running for a little while then stopping.

 

[JohnR725]

3 hours ago, fellerts said:

It sounds like all your donors suffer from the same problem... How is it possible for so many movements to have reduced endshake in the escapement? Someone correct me if I'm wrong, but endshake typically doesn't change unless someone goes in there with excessive force or a jeweling tool, or perhaps changes out components with no regard for them being matched at the factory as John suggested.

I'm not sure what I'm getting at, I just find your situation very curious. Are we missing something here?

Yes that's the interesting question isn't it? It gets even more interesting in that we have apparently three different movements that are all basically very similar but all have exactly the same problem which would be normally impossible.

Notice that I made a reference to one of the questions I always ask which is what is the condition of the watch for servicing? But here we have apparently the repair of three watches simultaneously. So did all three watches come from the exact same location as may be possibly they had a pre-existing condition which is why they were acquired in other words they didn't work from some previous repair person? So basically a lot of these questions are asked to determine where the problem may have occurred pre-existing or?

Then it's always nice if we see a picture of the complete movement. Many times not necessarily for this question but many times people will see a picture of a movement and recognize the problem even if they don't recognize the movement number. This is why a picture of the watch being worked on is always nice. Instead of pictures I will give links which bring up another problem? The other problem is the dates of the watches these are all from the 40s that makes them how old exactly? How many times a babe and worked on?

Oh and since these are bumper automatics tech sheet is attached unfortunately if you read the fine print it only relates to the automatic it does not relate to the watch itself because classically Omega assumes that you actually know how to service a watch. Which is actually quite frustrating because Omega leaves out a lot of stuff on the service their watches.

https://ranfft.org/caliber/8433-Omega-351

https://ranfft.org/caliber/8417-Omega-3010RA-PC

https://ranfft.org/caliber/8401-Omega-2810RA-PC

Now I would go on and speculate with ideas but will I get in trouble again?

19 hours ago, tb1982 said:

1: I did NOT start on vintage watches but have disassembled and re-assembled multiple ST36, Unitas and Seiko movements and re-assembled to better than before condition. I am not sure the criticism is helpful or necessary in this case. 

I'm going to assume the criticism that you perceive came from me?

 

 

Repairing-Omega-self-winding-watches-bumper.pdf

[tb1982]

yes, this is why i posted here is it seems t be something specific to this series of watches, however I have focused on one watch in an attempt to focus and fault find and not get utterly lost

[RichardHarris123]

5 hours ago, JohnR725 said:

hat's the interesting question isn't it? It gets even more interesting in that we have apparently three different movements that are all basically very similar but all have exactly the same problem which would be normally impossible.

Let's start again.  Unless the movement was a new concept and not proved, then the same issue couldn't happen to all of them, but no, it's a tried and tested movement.

So, the problem isn't with the movement, your doing something wrong, let's find out what it is.  @JohnR725 wasn't criticising you, nor am I, we just want to discover the problem and help you. 

[tb1982]

One thing is certain: I am doing a LOT wrong .... lol! 

 

Update:

I got one movement running last night (Cal 351 bumper - by trying to find the combination of pallet fork/base plate and escape wheel that has the most frisk movement). It ran all night and continues to run on the timeographer (though fast with notable beat error). 

However  - every single movement arrived from ebay in the same condition. "Runs for a few seconds or minutes then stops". It's curious to me that all movements appeared to display a fault in the same way. Some of the movements are more beat up (worked on, scratched than others). On "stopping" it always seems to be linked to escapement (not barrel/spring). I understand that scavenging parts from 4+ movements is slightly insane but it's what I have and certain parts are scarce and I've read a lot on the interchangeability of the parts,

I seem to be able to consistency install a clean, free running barrel and wheel train, i seem to be struggling with precision (end shake, cleanliness, alignment) of the escapement (balance, pallet, escape wheel). That seems to be a pattern.

Now that I have one movement working I'm going to focus on this movement. I was able to get the fork whipping back and forth in a frisky manner on the power test. I even used the same fork that was installed on the movement I filmed and described in an earlier video (the 30.10 RA). However in this movement (Cal 351) the fork was very frisky and worked well. So I can only assume the prior movement either had a bad (too tight) escapement or too bridges etc. 

I will now let the movement settle, de-magnetize it and continue to observe it. If i get one working watch out this bag of parts I would consider it an acceptable outcome. It's certainly been very educational. 

[RichardHarris123]

What did you do, differently to before? 

[nevenbekriev]

Ok, let me say what I see.

Looked again both videos. I am pretty sure that what happens is not due incorrect depth of the escapement. Can say nothing about the height position of pallets/escape wheel, but again, the problem for sure is not there

The movement behaves as like the pallet fork is not completely free, but near the end of the second video, it seems that the escape wheel acts lazy, even didn't advance for a moment when it was released and should advance. this suggests that something in the train is not free. More - looks like the obstruction appears periodically.

OP, now about axial free play. It must exist. In practice, if it is bigger than 0, then friction will be normal. When it is close to 0, then friction rises as shoulders of the staffs or pinions are pressed between jewels. Big free play is something not good, but if pivots still can't get out of the holes, the friction will be OK. You say there is almost no free play. May be it is OK, but better prove that the pallet fork is really free. For this You need to have it alone  in the movement (at least no escape wheel and balance). If it is free, you will be able to shift it by gentle jerking the movement or with very slight blow of air, or even alternating the position of the movement, as the fork is not poised. Then, check the freedom of escape wheel, alone again. It should rotate by slight blow and rotation would not stop immediately. Check again separately the rotation of 4th wheel. 4th wheel - You said it is replaced? The long pinion for the second hand was broken? You don't put the dial when testing movement, don't you? As the long pivot may touch the hole of the dial. Or the hand bush when ihand is on may touch the hole, and this usually happens periodically.

Not only missing axial free play may lead to lack of freedom. The other frequent reason is bent pivot. But other reasons exist - it is possible that pinion diameter is larger than it should be and the hole is 'narrow' for the pinion. Such thing may happen if a wheel is replaced...

 

[RichardHarris123]

11 minutes ago, nevenbekriev said:

More - looks like the obstruction appears periodically.

Yes, sometimes snaps back and forth, sometimes not. To me, an intermittent fault is harder to diagnose than a continuous fault. 

[Neverenoughwatches]

1 hour ago, tb1982 said:

However  - every single movement arrived from ebay in the same condition. "Runs for a few seconds or minutes then stops". It's curious to me that all movements appeared to display a fault in the same way. 

This is the most common occurrence in all vintages watches. The most common cause being seized up due to dried lubrication. Its not an indication that they all have the same mechanical fault. Its one reason that a movement should at least have a pre-clean before trying to diagnose issues.

[JohnR725]

2 hours ago, tb1982 said:

yes, this is why i posted here is it seems t be something specific to this series of watches, however I have focused on one watch in an attempt to focus and fault find and not get utterly lost

By the way this is a two-way street? What I mean by that you're currently now focusing on one watch which is good but we started off with three watches lots of pallet forks lots of swapping lots of things and maybe were lost? Plus you have the home court advantage of seeing the watch we really needed a picture of the entire watch because there are other things?

I find it's nice when you're assembling a wristwatch only assemble the things that you actually need to get the watch to run. Often times overenthusiastic people on this group will assemble the entire watch place it in the case only then place it on the timing machine typically only in one position and? Yes I am thinking of other discussions somebody discovered their watch I think this was an Omega didn't run on the wrist oh dear or only when it's in the case to the discovery maybe there's a problem it's much better if we find out these problems much much sooner so yes their stuff that does not have to be attached and we can verify the watch runs.

Yes there was something in one of the pictures that bothered me. Then as I pointed out what's nice with everybody in the group we all have different experiences of problems so we all do see different sources are problems. Oh well only if we can see the watch?

As we need to see the watch we can look to the watch guy you serviced two different watches may be more. But I don't have a lot of time right now so Us look what he has the second one has a much better picture of something it doesn't have to be on the watch and definitely is a source of lots of problems.

I'm also attaching a PDF of the 351 parts list which also brings up problems. You'll notice that it has the new number 351 as they change their numbering schemes and it also has the old number. Which is what I was looking for what I found the second watch guy webpage. You do have to be careful on multiple generations of watches with base calibers because the revisions of parts for the specific caliber are usually different so this comes back to mixing and matching can be an issue plus throw in a Omega conceivably we don't know may have revised stuff over the production time span and were never going to know that typically

https://watchguy.co.uk/service-omega-calibre-351/

https://watchguy.co.uk/teardown-service-omega-bumper-28-10-ra-sc-pc-350/

Let's look at one picture from the second link. Plus something snipped out of the parts list. Part number 1249 does not have to be on the watch right right now. I'd be curious as to how you removed it from the watch as should I list out all the bad things that can occur? Well bad things can occur they are then we have part number 351 definitely is not on the watch right now hopefully? Plus the offending spring 1255 and yes this one little component can cause the entire watch to stop if it's not properly done. So at this instant a time none of these things should be on the watch.

 

 

1364_Omega 351.pdf

[Neverenoughwatches]

1 hour ago, tb1982 said:

understand that scavenging parts from 4+ movements is slightly insane but it's what I have and certain parts are scarce and I've read a lot on the interchangeability of the parts,

Parts may be made the same, they might not be adjusted the same in the factory though. Interchangeability information may not take that account. These are old watches so even despite any discrepancy in factory setting, how many other hands have they been through that have adjusted that part ?

How closely are you looking at the part to see if it's exactly the same and adjusted the same ?

[JohnR725]

4 minutes ago, Neverenoughwatches said:

This is the most common occurrence in all vintages watches. The most common cause being seized up due to dried lubrication. Its not an indication that they all have the same mechanical fault. Its one reason that a movement should at least have a pre-clean before trying to diagnose issues.

This is one of the reasons why people assume cleaning will fix all problems as for quite a few watches cleaning will fix the problems. Especially if certain conditions are met. In other words hopefully the watch hasn't been worked on by anyone else in the past and left in a non-running condition. Had been lubricated with organic oils that went bad so watch just came to a stop. That's actually a good thing for organic lubricants the watch stopped in did not wear out. But now that we of modern synthetic oils they typically just spread across the plates never seen again and on early automatic watches are definitely a problem for the automatic components that did not have jeweled bearings and if the watches continuously run cleaning will not fix the problems and it will disintegrate.

Now we end up with a interesting problem for  pre-cleaning is it good or bad? I know of people work and Rolex shops and all watches are pre-cleaned. So that were all on the same page here the watch is disassembled in other words hands and dial come off possibly the calendar ring but not always as one of the calendar rings apparently can be pre-cleaned. But typically anything that's painted comes off entire watch is run through typically a separate machine than the normal cleaning machine.

Now in the watch is look that it's nice and clean as Rolex is obsessed with and shakes they can properly check that they can do a nice evaluation and continue on with their servicing but his pre-cleaning universally accepted by everybody?

Your timing is quite interesting because yesterday we had a discussion about this at work. Where I work we have another watchmaker who typically is somewhere else but every couple of months he comes to join us for a couple weeks and we did have a discussion about pre-cleaning

so Josh's thoughts on pre-cleaning are like arriving at the scene of a crime and it's been cleaned. In other words the body is gone and we did make a joke it's been cremated. The entire scene's been cleaned everything is been patched everything is been fixed and how exactly do we evaluate the condition if we can't?

As Josh is typically doing a lot a wristwatches including vintage he looks for things like filings which disappear with pre-cleaning.

So we do end up with interesting problem here.

17 minutes ago, Neverenoughwatches said:

Parts may be made the same, they might not be adjusted the same in the factory though. Interchangeability information may not take that account. These are old watches so even despite any discrepancy in factory setting, how many other hands have they been through that have adjusted that part ?

One of the problems we run into is parts listings and even service bulletins were written at an exact point of time. For instance I was doing a project with somebody working on a 12 size Illinois watch He was very happy because the watch had been made for 30 years and all the parts according the parts book interchange. But the reality was over the 30 years they change things lots of things they just never revise the parts book at all. Even things like our wheels initially in the project because they're all the same we removed all the our wheels and discover later on that they're all sized slightly differently. In the early days of especially pocket watches that are typically made in batches and parts may not interchange between the various batches. The earlier watches even possibly something from the beginning of the batch to the end of the batch might not interchange as there is a lot of hand fitting and machineries would go out of tolerance

plus revisions do we ever see the revisions? I know Omega has revisions not only do they have revisions but they have documentation comment to specific calibers at least newer calibers where they talk about specific problems for those specific watches plus revisions of parts. Whereas the revised part numbers do not have any designation that they been revised which I find quite annoying. So often times you will see the original parts were these the upgraded parts were these there may be a color difference or they'll tell you how many wheels in the teeth or something but if you don't have the revision document that's going to be a problem

then anything from or specifically vintage related to the escapement is going to be a problem if you swap only one of the components and do not understand exactly what you're doing as they typically will not work not without some form of adjustment. This is why students in schools such as  wostep spends so much time adjusting escapement's as if you work on anything a vintage you're going to have to understand how to do  that. 

 

[Neverenoughwatches]

39 minutes ago, JohnR725 said:

but his pre-cleaning universally accepted by everybody?

Maybe good and bad in different ways. I see that it can give a repair guy the opportunity to evaluate a running movement before it's taken apart, in this way the repair guy has not introduced any of his own his  mistakes. So the whole assembled basic movement is precleaned less the balance and pallet fork. Instead of not being able to assess the movement because its parts are stuck together. Just by hanging the movement from a wire into a US machine in a cleaning jar. It's nice not to have to deal with such dirty movements and I've found they come apart a bit easier.

[JohnR725]

9 hours ago, Neverenoughwatches said:

whole assembled basic movement is precleaned less the balance and pallet fork.

Pre-cleaning at least in service centers typically would include the balance wheel and pallet fork. In our previous location when we had a Specific machine for pre-cleaning I would pre-cleaned the pocket watches and they did include the balance wheel and pallet fork. Although the pre-cleaned machine really wasn't happy with something as large as an intact pocket watch intended to vibrate quite a bit. With the baskets on top of the machine usually falling to the floor.

Then one is talking the Josh today that used to work in the Swatch group service center asked what their policy was and no pre-cleaning. On the other hand Swatch group service center doesn't do vintage and typically cleaning would fix the problem. That is if the watch even really had a problem other then it was time for an overhaul. Then of course they would probably change the mainspring barrel and the escapement components. So basically disassembled cleaned reassemble lubricated only if there's some sort of problem with a deal with it but apparently they didn't have a lot of problems. As basically these are brand-new watches at least by the standards of this group are probably less than 10 years old.

But as I mentioned I know Rolex service centers they always pre-cleaned and typically have a separate machine for that.

9 hours ago, Neverenoughwatches said:

Just by hanging the movement from a wire into a US machine in a cleaning jar. It's nice not to have to deal with such dirty movements and I've found they come apart a bit easier.

One of the ways the hobbyist could do pre-cleaning would be basically to ultrasonic in a fluid such as lighter fluid or any type rinsing solution. Versus actually running it through a multistep cleaning machine which isn't always really necessary.

Then yes having a reasonably clean watch that the gears spin And the balance wheel turns and you can verify that yes the watch runs. Then if you're concerned about a reasonably dry watch put a little oil on it. After all you're in the evaluation phase are going at some point in time disassemble and properly clean it. Is amazing what a little fresh oil will do on a clean escapement for instance. But yes it's definitely nice before the complete servicing to discover if there is problems. Because ideally this is the time to fix the problems as opposed to surprise my watch doesn't run and it's now back in the case which occasionally happens on this group.

 

[tb1982]

Update 

 

1: it’s amazing what everyone can see form the video. I will post more but have to head out for work travel tonight (maybe I need a break from staring at a microscope for 5hours a day!)

 

2: I repeated the test for fork freedom and it wiggles around wit  a decent air puff (needs a solid and direct puff so not super slick but it moves)

 

3: watch ran for 48 hours so I tried to assemble the automatic winding and add dial and it stopped immediately. Removed both and paused. I now wonder if it’s the friction from the dial or other parts. Will test 

4: based on  advice here I will install each wheel individually and test its freedom and try and not damage anything else with so many disassembly and reassembly cycles 

 

5: to answer JohnR725, all three parts are on the movement and all three are originals. Part 1249 was removed was removed with a compression spring watch hand remover tool and yes it’s quite a risky operation…

thank you for all the help on the journey look fwd to sharing more videos since it’s unbelievable what you are able to notice from the media 

 

 

Should clarify that my “fork test” I meant puffing air onto fork on its own with no balance or escape wheel 

[tb1982]

I added two more videos . The first shows the watch failing to run, the second shows the watch runs when the bridge (I do not know the name of this bridge) is removed 

 

 

[Mercurial]

In the first video where the watch is failing to run, the centre seconds drive wheel isn’t moving, even when the balance is oscillating. 

In the second video where the watch is running, the centre seconds drive wheel is turning as it should.

This suggests that this wheel is getting fouled against the bridge that partially covers it in the first video. 

This could be because that wheel has been bent when removing it, such that it is no longer flat, or perhaps it is not staked back on far enough and is sitting too high on the extended pivot that drives it. 

I hope that helps,

Mark

[Knebo]

Exactly as @Mercurial wrote. That must be it. 

If it's not the wheel, which it 99% is, also check that the bridge isn't bent (I had that once).

[Jon]

With all indirectly driven second hand movements such as this one, I always test that the movement runs well without the wheel over third staked on or the sweep second pinion and brake spring in place either with or without its own cock, as some do and some don't. Only the basic wheel train should be seen working. Great to see the 3rd wheel arbor spin flawlessly within its jewel without the pallet fork in place, then you can cross that off the list knowing it isn't bent. Test the wheel over third for flatness by placing on a staking block, then cross that off the list. Then stake on the wheel over third (properly) and check if anything has changed on the timegrapher (I like to spin the wheel train at this point and check that the wheel over 3rd is staked on perfectly because you can see it spin quickly if the pallet fork isn't in place), then place the sweep in place and see if that mucks up your timegrapher readings without any brake spring first, then with it. Then add more parts and check.

So, at every point you add a component or adjust something, take readings. If you are methodical in this way, you will find the problem and what caused it.

Inspection of parts is key. One bent wheel or bridge and fouling will occur as you are having.

Edited 15 hours ago by Jon

[tb1982]

Thanks all.... I believe I found where it is fouling! It is the small bridge that covers the seconds hand pinion. I seem to have bent the spring that sits between the indirectly driven seconds pinion and the tiny bridge that covers it.

It's not obvious to me how the small bridge (part 1010) sits relative to the small spring (part 1255)....does anyone have experience with the Omega bumpers like Cal 351 where they have this indirect mechanism to drive a center mounted second hand?

What is the purpose of this spring? Is it to maintain tension on the gear of the seconds hand pinion?

Does the spring sit between the second hand pinion and the first screw of the bridge? This is absolutely where the watch is losing power and i have finally identified the issue with everyones help

also i wanted to express my gratitude to everyone taking the time to observe and offer assistance, i was about to give up

[JohnR725]

On 1/10/2025 at 12:43 PM, JohnR725 said:

Plus the offending spring 1255 and yes this one little component can cause the entire watch to stop if it's not properly done. So at this instant a time none of these things should be on the watch.

5 hours ago, tb1982 said:

I believe I found where it is fouling! It is the small bridge that covers the seconds hand pinion. I seem to have bent the spring that sits between the indirectly driven seconds pinion and the tiny bridge that covers it.

notice my quote of me? sometimes in my long-winded messages things may be perhaps get lost. But there's a reference to the spring and the entire watch can stop which I believe you're having now? which is why when you're having a problematic running watch you do not put things on that you do not need. So for instance you can remove the bridge and remove the pinion and see if the watch will run. 

5 hours ago, tb1982 said:

What is the purpose of this spring? Is it to maintain tension on the gear of the seconds hand pinion?

the problem with this type of way of driving a secondhand is you end up with too much play between the driving gear and pinion. so basically that little tiny play in the pinion translates to the secondhand and the secondhand will drift around by quite a bit. so the spring has to provide enough force to keep the pinion in place but not to either stop the watch worst-case or reduce the amplitude down to an unacceptable amount.