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Discussion Starter #1
I've spent the whole week focussed on just one watch - a lovely 6139-6002 (and no, not my own watch that I pictured in todays WRUW thread).

Last Saturday I stripped & cleaned it. The movement was lovely, by which I mean no rust, no obvious signs of damage and although the barrel arbor bushes were badly worn I couldn't see any other damage or other wear (well, not totally true, but I'll update on that later on and it didn't have any bearing on the service). It had two service marks scribed into the caseback.

It came with the common issue of a snapped off crown, so needed a new stem and crown. It didn't want to run despite being fully wound, so rather than try and investigate possible causes I set about the service.

I was so confident in what I'd seen post cleaning and jewelling the barrel bushes that I rebuilt the whole movement, including the dial side (but not fitting the dial & hands) before doing the final balance cock diashock cleaning and popping it on the timegrapher with a full wind.

I have done so many of these movements that I can tell almost immediately what I've got once the timegrapher picks up the first signal.

And what I got wasn't what I was expecting or wanted :-(

I got a very low amplitude - around the 180 mark which after settling barely broke 190. And a rather jittery, erratic trace.

Grrrrrrr.

That is not what anyone wants to see. I'd done what I thought was a very good job of cleaning the movement parts, and rebuilding them to ensure no foreign objects had got in. I'd then oiled it meticulously and was thus rather puzzled.

Still, the timegrapher never lies so there was clearly an issue.

I'll update this thread a little later on with my investigation and findings, but would be interested if anyone can guess what the ultimate cause of the low amplitude reading was? This movement should be running at 240+ post service.
 

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Well, with the erratic trace I am going to guess something In the escapement; such as a bad escape wheel or pallet or possibly worn balance staff pivots. Do tell.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #6
So ..................................................................

The first thing I did was to swap in another balance / balance cock. Now the two that I have in my spares trays were in a slightly unkown state - they were there for a reason, and that was not to be ready to drop in to a needy watch.

So, when I got similar timegrapher readings I had to take them with a slight pinch of salt. But - the main problem (and to be clear that's abnormally low amplitude) persisted.




OK, so next up was to swap out the gear train components. In the past I have tended to do this one at a time. But, as those of you who know, this is time consuming.

And, it has to be noted it is risky. Every time you strip a movement down there is risk. Risk of a ping (not so common these days, but it can happen). Risk of damage (very uncommon thankfully, but it can happen, either by clumsiness, or just bad luck). Risk of foreign objects (typically micro fibres - hard to protect against in a non clean room environment).

So, I decided to swap in replacement 3rd wheel, escape wheel and pallet forks. And, basically got the same result (I didn't get exactly the same readings - already too many variables, but what I didn't get was a 'woo hoo' reading). I guess all of the above took a couple of hours. I never rush, and was trying to be ultra methodical and careful - so as not to miss the obvious (which I figured must be waiting in there, staring at me).

At this point I went to bed. I'd had enough of this movement at that point and was digging myself a hole. I hoped that sleeping on it might reveal the simple answer as soon as I took a fresh look at the movement.

I had noticed this:




which is obvious when you know what to look for, but maybe this picture will help




so I went to bed with an idea and a plan.
 

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If that jewel to the pallet is cocked or not set correctly it may be binding up the pallet fork. Maybe too little end shake on the pallet fork.
 

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

The first thing I did was to swap in another balance / balance cock. Now the two that I have in my spares trays were in a slightly unkown state - they were there for a reason, and that was not to be ready to drop in to a needy watch.

So, when I got similar timegrapher readings I had to take them with a slight pinch of salt. But - the main problem (and to be clear that's abnormally low amplitude) persisted.




OK, so next up was to swap out the gear train components. In the past I have tended to do this one at a time. But, as those of you who know, this is time consuming.

And, it has to be noted it is risky. Every time you strip a movement down there is risk. Risk of a ping (not so common these days, but it can happen). Risk of damage (very uncommon thankfully, but it can happen, either by clumsiness, or just bad luck). Risk of foreign objects (typically micro fibres - hard to protect against in a non clean room environment).

So, I decided to swap in replacement 3rd wheel, escape wheel and pallet forks. And, basically got the same result (I didn't get exactly the same readings - already too many variables, but what I didn't get was a 'woo hoo' reading). I guess all of the above took a couple of hours. I never rush, and was trying to be ultra methodical and careful - so as not to miss the obvious (which I figured must be waiting in there, staring at me).

At this point I went to bed. I'd had enough of this movement at that point and was digging myself a hole. I hoped that sleeping on it might reveal the simple answer as soon as I took a fresh look at the movement.

I had noticed this:




which is obvious when you know what to look for, but maybe this picture will help




so I went to bed with an idea and a plan.
I did too but my wife wasn't so keen......
 

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Discussion Starter #12
So .................................... having slept on the problem (not literally!!) I started another day hoping to find the root cause.

Having (probably) ruled out the balance, and also ruled out the 3rd wheel, escape wheel and pallet forks I figured that maybe the priblem was with the mainplate.

I'd spotted the manufacturing defect where the jewel (or tool) for the pallet forks had clearly been missaligned when first pressed, but was this the issue?

I had also jewelled the mainplate (due to significant wear) and as with all things, its always easy to suspect that maybe I'd done something wrong when I did this and maybe set the jewel off centre etc.

So, after microscopically examining the mainplate, and then comparing it to another one, even though I could not see anything wrong as such I decided to swap in the alternate.

I also decided to swap in another mainspring (barrel complete) that I had rebuilt.

Examining (again microscopically) the teeth on the original barrel I could see wear, and also (even after cleaning, tiny burrs of brass). I guess that a lot of force is generated at this point, and as the brass teeth of the mainspring barrel mesh with the steel teeth of the centre wheel there can only be one winner.

So, (I say this word a lot) I then had to rebuild the movement. I decided to only build enough for the movement to run - so no cannon pinion, no clucth levers, no minute wheel etc.

With the movement rebuilt (and at this point there aren't many original parts) I popped it back onto the timegrapher and got, wait for it, yep. A low amplitude.

OK, so what haven't I swapped?

Ah yes, the barrel bridge. And the pallet cock.

I swapped in a NOS barrel bridge and a NOS pallet cock.

Back onto the timegrapher. Yep - low amplitude.

At this point I'm feeling like this watch must be possessed. I'm also doubting my skills. If every watch service went like this one I think I would have stopped years ago.

I stopped (again) at this point. I wasn't beaten, but I wasn't feeling like a contender.
 

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Simon, I feel your pain. I recently had time to go back into my 6138 Bullhead I serviced about a year ago. The 6138B moment had some miles on it and I never really achieved great amplitude numbers, only around 212. I figured while in there I would upgrade the upper MS barrel arbor bush with a jewel. Not including the original service, I ended up rebuilding that movement 4 times and only ever achieved mid to low 220s on amplitude while trying a number of things to increase the amplitude each time I was in there.

I was talking to Tom Robinson on the phone recently and he relayed a similar story with a customer's 6139. He ended up just pulling another movement from his spares and rebuilding that one for his customer.
 

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I admire your persistence Simon!

I'm glad I'm not the only one who runs into issues like this...........lol

I can totally relate to the mind boggling number of hours put into some of these rebuilds. It can be frustrating to say the least and not only that it can hold up moving forward with other work at hand
 

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Are the diashock jewels upside down, Or 0ne of them ?, Debris in the diashock jewel collar ?

I should add the jewel in the diashock in the main plate as the balance complete has been switched...
 

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What happens to the amplitude when the chronograph is running? Could the vertical clutch be adding drag to the movement?
 

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Discussion Starter #17
What happens to the amplitude when the chronograph is running? Could the vertical clutch be adding drag to the movement?
when the chrono is running, the centre chronograph wheel is rotating as a single unit.

With the chrono stopped, the two levers lift the clutch plate and effectively clamp it preventing it, and the axle/pinion that the seconds hand is attached to from rotating. The wheel of the chronograph wheel continues to be driven by the movement, and rotates freely on the axle/pinion. In my experience, this adds drag (friction) to the movement and drops amplitude by a small amount. This is why it is important to oil the centre chrono wheel (as per the technical guide) rather than running it dry.
 

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I know how it works, I was asking if your movement is affected by it, and by how much, as others have found amplitude issues with gummed up vertical clutches.
I'll get me coat.
 

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Discussion Starter #19
Well, while we are on the subject of centre chronograpoh wheels I will continue documenting my 'journey'.

After sleeping again on the issue I decided that whilst I didn't want to, I was going to have to swap in a centre chronograph wheel, on the basis that this might be the cause of the issue. I say that I didn;t want to, because if this was at fault, then the cost of the service (repair) has just almost doubled - which is not a message I want to give to the owner.

I had (again, meticulously) examined the original under high magnification. This is a good thing to do, but also a pain, because you spot things that you sometimes wished you hadn't.

What I did find, was that like the teeth on the mainspring barrel, deep in the grooves of each tooth (and not every tooth, just 20 or so) they were micro particles/burrs of either brass, or hard dried oils. So, before I swapped it out, I set about cleaning each tooth. I did think about counting them, but gave up. Let's just say there are a lot.

Once cleaned, I rebuilt the movement (again), and tested it and no, my cleaning hadn't made any (positive or negative) difference.

Anyway, back to 'franken' movement.

I had just received my latest 6139 'Pogue' and looking at the movement it looked very nice. :)

So, I stripped it down, and specifically cleaned and oiled the centre chrono wheel. And I swapped it into the bad movement. And, of course it made no difference.

OK, final chance. I cleaned the chronograph bridge (from my new watch). And swapped it in. And .................... no difference.

Oh yes, I did swap in the balance assembly from the new watch, suitably cleaned and oiled. And ............................................................... no material difference. So, that (in my opinion rules out the balance). And in case you're wondering I had also previously swapped out the mainplate lower diashock assembly (way back in this process).

So, let's examine the facts (as I was seeing them).

1 - the original watch is serviced exactly like I have serviced dozens of 6139's

2 - the original watch runs (after the service) with a cr$ppy low amplitude. Between 180 - 200. I would expect (these days, and from the state of the movement) to see 240+

3 - I have replaced just about every part of the movement, bit by bit until I end up with a movement made up of differnet parts. And this movement exhibits the exact same issue.

4 - When you say it like this (which I did, to myself and the wall), it sounds bonkers.


At this point I made the painful decision that enough was enough. I put the movement down and told myself that I'd done my best and tomorrow I would rebuild the original movement and have to live with it.
 

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Were the 2 service markings the same jeweler ?
 
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