Omega 351 bumper movement - sweeping seconds problem

[Dmitry]

Hello Team,

has anyone ever had the pleasure of working on the Omega 351 bumper movement?

My question is specifically about the sweeping seconds pinion that makes my movement stop. It should not stop my movement, but it does. 

The pinion looks OK, but it only runs for a few seconds and then stops. Are there any tricks with that pinion?

To make sure it is the pinion I have removed the autowinder and the seconds pinion / hand and the watch is running perfectly since.

Anyone has schematics or a picture of how the pinion is supposed to me attached to the wheel and the position of the spring that keeps the pinion in check?

Thank you.

Edited November 16, 2021 by Dmitry

[Nucejoe]

Are you sure  the spring isn't pushing on pivot of the sweep arbour, which shouldn't, spring is just to keep the sweep arbour from falling. Face down a ,01mm gap between the spring&sweep arbour is good and should be lubricated too.

Other possibilties are, minute wheel might be rubbing on gear bridge or bent sweep arbour.

Regs

 

[JohnR725]

  On 11/16/2021 at 8:27 AM, Nucejoe said:

sweep arbour from falling. 

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Usually the sweep spring is to keep the secondhand from wobbling around. That might not be a correct technical term but there is play in the pinion gear combination and the spring puts tension so that the secondhand will sweep smoothly. Otherwise you'll have the secondhand cut out wobbling around.

  On 11/16/2021 at 8:27 AM, Nucejoe said:

Are you sure  the spring isn't pushing on pivot of the sweep arbour, which shouldn't,

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Then yes this is a valid answer the spring has to push wherever it is supposed to push. There should be something underneath opinion of flat surface it pushes on occasionally I've seen some that have washers it has to push on something and not the shaft itself and is also not supposed to bind up than they are either it's just data provide a little bit attention to keep the hand from wobbling That's all it does.

 

  On 11/16/2021 at 6:05 AM, Dmitry said:

Anyone has schematics or a picture of how the pinion is supposed to me attached to the wheel and the position of the spring that keeps the pinion in check?

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The answer would probably be no. It appears to be there all Omega has for this caliber is the parts list some of the parts are for this and then the base calibers another movement. Probably at one time as what Omega does currently with their documentation is there is probably a supplemental sheet somewhere that explained how to do the spring's that no one is ever seen because it only was in the factory service centers or wherever in the world.

[Nucejoe]

Thank you John, yes " keeping the secondhand from wobbling" is clear to understand, "correct term"

Underside of pinion comes in contact with the jewel underneath it and should be oiled as well as the top side that comes in contact with the spring.

I check both underside and top side of the pinion  under microscope to make sure its smooth surface, not chipped off or otherwise faulty. 

I think the problem here is more serious one, perhaps a bent seconds arbour.

@Dmitry was it running before you take it apart? 

As John has said many times before a bit of history helps.

Regs

[Dmitry]

Thank you for your feedback.

I do not think that the pinion is bent. It appears to be in great condition.

The spring is supposed to push on something, indeed. I have tried to setup the spring to push the pinion away from the minute wheel as the watch would stop and sweeping would be jerky, this is why I believe that the spring must push the pinion towards the minute hand.

I think I am missing a part here, hence asking for schematics. The 351 does not have a jewel for that sweeping pinion, it is just a hole in the bridge. Having a jewel there would improve the construction IMO.

I think I am missing a part here - that washer you are referring to. I believe the spring must touch the pinion to push it towards the minute wheel, so they are in constant contact, but that spring shall not just sit under the pinion as pinion teeth will just chew on the spring. But at the same time I do not observe any extra space on the tip of the seconds pinion when setting the seconds hand. If I were missing a washer, the hand would sit higher by the hight of that washer.

Looking at the parts list for 351 I do not see any washers for this assembly.

Does anyone have a picture of proper working assembly of this element?

[spectre6000]

Disregard. I'm a dummy.

Edited November 18, 2021 by spectre6000

[JohnR725]

  On 11/16/2021 at 4:08 PM, spectre6000 said:

I could be way off base, or there could be parts not pictured, it's out of focus, and other equally valid excuses to save face in the event I'm wrong, but looking at that first photo, the pivot on the third wheel looks like it's sticking way up out of its jewel. Almost like it's supposed to have a small seconds hand running super slowly for the watchmaker's amusement.

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When answering questions we make assumptions? We assume that conveniently something is missing in the picture.

Yes it looks like you can put a little tiny hand on that and only the watchmaker would see it but that's not why it's there. It's there to frustrate people like watchmakers who don't know what they're doing and that could be where the problem with this. There supposed to be a wheel that goes on that that drives the pinion. Because you notice right now nothing else does drive the pinion. Often times people have zero idea how to remove it and in trying to pry it up in the bizarre ways they do they cause the shaft to get bent. If it's bent and that wheel does not revolve properly it will cause attention driving the pinion possibly of all the problems described here console would be caused by this. But conveniently we were answering the question we only looked at the problem of the pinion because that is what the persons talking about.

For instance for that matter the rest of the watch if the rest the watch is barely functioning because somebody doesn't have a timing machine or variety of other reasons that are not aware of the condition of the watch it may be that just this last a little bit is enough to bring the watch to a complete stop. Not super likely but possible.

  On 11/16/2021 at 2:59 PM, Nucejoe said:

@Dmitry was it running before you take it apart? 

As John has said many times before a bit of history helps.

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Oh darn somebody beat me to my own question? Yes this is a standard question of what was the watch doing it before you took it apart.

The other thing to try is we've had this discussion before? To try doing a search in seeing if you can find any other answers because I know we've discussed this before on the group problem is trying to figure out how to ask the Proper wording to find the answer because often times people don't ask the right question in the title and the answer comes up later on and finding these things can be really hard.

  On 11/16/2021 at 3:31 PM, Dmitry said:

I think I am missing a part here, hence asking for schematics.

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You can ask all you want but if it doesn't exist it doesn't exist? If you look at how Omega does things today they will have a parts list pending on the watch sometimes it has technical drawings sometimes it does not. With some of their watches they will group common things together they'll be a common technical sheet for a whole bunch of watches. Then and these of existed since the 50s their separate technical stuff for things like cleaning the lubrication. But usually other than the parts listed exist because typically watch people need parts most of the summer technical stuff doesn't exist in the public domain. Plus it's an older watch like this even if you had access to a Swatch group account which you would need to access this they wouldn't even have the older stuff. The unfortunate assumption is that every single watch had a complete nice technical drawing is a nice fantasy but it just doesn't exist probably.

So for instance if I do a search of my computer to see what Omega documentation I have for this watch I end up with a folder labeled 351 and all it has three PDF pages identical to the  singled PDF found on cousins.

Sometimes you can search online and see if anyone else is ever service the watch they might have helpful pictures or not. The first link yes the service the watch but it's much here it is dirty here it is clean unhelpful the next link I have here he shows a tiny bit but that's about it.

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

Then I decided to waste some time? What is that may long time ago I bought out a watchmaker or at least I bought out the remnants of the watchmaker he was long since departed the jewelry store that he had sold Omega watches he had a little bit of Omega technical documentation from the late 50s early 60s.

One of the reasons I bring this up is sometimes on the documentation found from the material houses it's only concerned with hearts I've seen for some companies  you don't even get the full technical document because all I have is the parts list all the rest of the stuff is missing. Never being sort of converted the PDF or at least never available out in the open somebody there has to physically scan their document or if they have access to stuff behind a firewall that will have it but not the open.

So looking through the Omega stuff I found a couple watches with identical situations like yours the same spring the same drive same everything do they cover anything no they are more concerned with the automatic watch of the regulating stuff but one is looking at the picture of oh assumptions we made an assumption with you

Nucejoe In past conversations regarding this matter he has experience different than some of us and that is the drive wheel may no longer hold properly in place? When you put the drive wheel back on you do not push it all the way down tight against the plate or that alone will stop your watch it has to be up a little bit. It's possible with time but that gets loose and people will push it down tight and wonder why their watch doesn't run

Then I did find kind of a drawing for you? For this particular watch they explain why they use the indirect drive center seconds because basically it allows them to make a watch with no interference from the mainspring to the balance. Or basically no complications then there's a remark made of it allows them to convert watches that never came with a sweep second to a sweep second by just adding of the additional drive stuff there's no notes on adjusting the spring or anything but what would you get from the drawing is we can see your spring and your spring pushes on the bottom of the pinion but almost looks like the washer but that should be part of the bottom of the pinion and then you can see the drive gear which is entirely different how it goes on than yours but you can see how it meshes with the pinion

several other calibers use the exact same mechanism is yours so you should build a possibly Google sweep second spring irritation or something and may be somewhere out there because it is common as exact same problem which I know we've discussed in this group before use have to find it if you can.

 

 

 

 

[Dmitry]

@JohnR725 - I was very tempted to take umbrage with your seemingly long and didactically thesisized post. That is until I made it to the last two paragraphs.

You obviously took the time to share the knowledge you acquired for the benefit of the craft. And I truly appreciate this.

We all make assumptions, it is human after all. 

I knew better than taking the power wheel assembly off as I suspected that I would have had to used a staking set to put it back on, so while cleaning the movement I left it.

Your drawing clarifies a lot of things for me here. Obviously, I am not missing any parts, but am rather dealing with suboptimal design of the caliber. Your drawing clearly indicates that the spring pushes the pinion into the minute wheel and sits right underneath the gears.

I have since taken some 2000 grit sandpaper and ever so gently smoothed the shaft of the sweeping pinion, and have done the same with the tip of the spring. It is running now for a few minutes without stopping, so I will leave it overnight to observe before calling it a win and putting on the bumper.

The image I referenced in my original post was not of my movement, it seemed like too much hustle at the time, so I cropped the focal point of the matching image from the very sight you referred me to (https://watchguy.co.uk/service-omega-calibre-351/).

Your investment in sharing the image inspired me, so I felt it only appropriate to break out my macro and take some pictures to show that the clearance of the minute wheel is nominal, and I have also included TG imagery of two snapshots, with the sweeping seconds pinion removed, and on. 

If you can recommend any decent literature on how to interpret the oscillogram, especially the tic an tocs on the bottom, I will appreciate it very much.

Thank you.

[JohnR725]

  On 11/17/2021 at 2:35 AM, Dmitry said:

I was very tempted to take umbrage with your seemingly long and didactically thesisized post. That is until I made it to the last two paragraphs

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Interesting way to start an?

  On 11/17/2021 at 2:35 AM, Dmitry said:

If you can recommend any decent literature on how to interpret the oscillogram, especially the tic an tocs on the bottom, I will appreciate it very much.

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Now we get it interesting problem? I don't suppose you like Harry Potter? The reason I bring this up is somewhere in one of the stories one of the characters make some references to the exact science or crystal ball reading or perhaps the lack of.

YouTube is an interesting place there's a nice video which I have a link for but several people have  exact same video isn't that weird? I think at one time the watch company posted it and probably a lot of other people liked it so much they put it on their channel so this was just the first link I found

https://youtu.be/g5c5RK4WFV8

The whole purpose the video is to show how wonderful their escapement is but we can care less because will probably never Be able to afford one anyway. But at about one minute and eight seconds it is what you're looking for. For teaching is a wonderful video shows exactly where all five of the sounds come from how they overlap and unfortunately it's an idealized  perfect view.

For instance if you look at the PDF eventually oh come to witschi's on oscilloscope diagrams  how they compare to the idealized perfect ones in the video?

so the oscilloscope is really a useful tool but it does become subject to some interpretation. Ideally the very first sound the roller jewel hitting the fork should be quiet the locking in a crashing in the banking pins usually overlapping is typically really loud. Typically the middle stuff is kind of in between.

 for instance on page 16 of the PDF they show the oscilloscope and why might look undesirable even though they showed it somewhere else. But typically on a witschi timing machine you did not see it like that you only see the top part of the waveform.

 

Witschi Training Course.pdfFetching info...

Edited November 17, 2021 by JohnR725

[Dmitry]

  On 11/17/2021 at 6:32 AM, JohnR725 said:

I don't suppose you like Harry Potter?

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No, I don't. But I do like economics, which many consider pseudoscience.

 

We have a win! After all these modifications the old guy is runnng confidently and strong.

 

Thank you for support and good literature on how to interpret the chronogram.

https://1drv.ms/v/s!ArG5E62RGctxjbIYu5-PnFCu_jTwXw

What I love about my new hobby is that there seems to be no end in sight of what instruments one needs to get better in the art of watchmaking. There are tools to make tools to make tools:)

 

951424209_ToolsMaterialsoftheTrade.PDFFetching info...

Edited November 18, 2021 by Dmitry
changed video linnk

[JohnR725]

Usually for people using the timing machine they're not typically looking at a oscilloscope. Then depending upon where you acquired your timing machine from you might get a book that explains the graphical display. Kinda like the PDF attached which came with a much older timing machine. So basically you can see if you're running the way you're supposed to or clues of why you're not doing what you're supposed to and clues of where you might find the problem. Then if you see total garbage on the screen you know you have a serious problem.

The oscilloscope is a nice interesting feature but most people are looking for the graphical display and how to interpret it. But I do admit because the nice witschi machine at work has the oscilloscope I do look at it. But to a certain degree it's kind of like a crystal ball that subject to some interpretation and may or may not be an exact science. I suspect if you're in a factory looking at watches go by that all be identical it would be much better than randomly look at watches that are all little different and it may all be perfect or not.

Then if you like tool catalogs here's a link to one even downloaded in a variety of formats. Even though it's a little on the old side you will notice that a lot of the watch repair tools are identical to what they are today they haven't changed in the last hundred years. Unfortunately the price has

https://archive.org/details/20thcenturycatal00purd

Then while you're here you can try to do various horological searches and see what other wonderful things are lurking.

Timing-Machine-Charts.PDFFetching info...

[spectre6000]

  On 11/16/2021 at 8:42 PM, JohnR725 said:

When answering questions we make assumptions? We assume that conveniently something is missing in the picture.

Yes it looks like you can put a little tiny hand on that and only the watchmaker would see it but that's not why it's there. It's there to frustrate people like watchmakers who don't know what they're doing and that could be where the problem with this. There supposed to be a wheel that goes on that that drives the pinion. Because you notice right now nothing else does drive the pinion.

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Yeah... My daily forum crawl occurs simultaneously with my daily caffeination ritual (and is, coincidentally, the first stop). Not a great combination. The tiny hand thing was intended as a joke, but I guess my funny bone also needs stimulation before it can do its job in the morning. I need to figure out how to open up some time later in the day when my brain is firing on at least half its cylinders.

Edited November 18, 2021 by spectre6000