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ETA 2472 low amplitude - impulse jewel fouling pallet horn?


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Hi knowledgeable people!

I'm working on an ETA 2472 these days. This one comes from a "Timba Autom-datic" [sic] and was barely running. After cleaning and reassembly (no oiling of the train) it still wasn't running great: <200° amplitude and inconsistent beat error. The train, balance and pallets look good in isolation. There seems to be sufficient end-shake on the pallet fork which clicks over without problems if I nudge it when the mainspring is under tension. Additionally the balance alone will spin freely for well over 60 seconds when encouraged to do so by my air blower. The train moves very smoothly with significant recoil.

The potential problem reared its head when I installed the balance, pallet fork and pallet fork bridge and nothing else. If I give the balance wheel a puff with the air blower, it seems to abruptly come to a stop after a couple swings with the impulse jewel resting between the pallet fork horns. I have verified that the impulse jewel has good clearance to the guard pin, so my best guess at the moment is that the impulse jewel is touching the "crotch" of the pallet horn...

Here's a video of what I'm seeing:

And some hopefully relevant pictures. I don't see anything wrong with the balance or pallet fork. The impulse jewel looks straight and is not loose.

2055385771_IMG_3388(1).thumb.jpg.09cb5fab5f680ca1c46e10a4573f642a.jpg 2138751779_IMG_3389(1).thumb.jpg.36cc411f14a67adea38a357899f2217a.jpg 485829382_IMG_3394(1).thumb.jpg.547b9aa2a153ffeca53136b1cf1aec4e.jpg

Unfortunately I find it very difficult to get an angle to observe the interaction between the balance and the pallet fork on this movement. I also don't know if the test in my video makes any sense, but in my mind the balance should be able to knock the pallet fork around for a few periods at least. Has anyone seen something similar before and could provide some guidance?

cheers,

Fredrik

Another observation: When the impulse pin is at rest between the horns, I can nudge the balance wheel and observe the pallet fork moving along even without the jewel touching the two protruding forks. This tells me that there is contact between the impulse jewel and the root/base/crotch/flat face (someone please tell me the correct terminology) of the pallet fork. Of course, I'm not sure, but I don't think this is supposed to happen.

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I have lost the luxury of watching videos ( disconnected vpn ). 

You own tests and analysis are sound, you are very close to the location of the fault. 

You show the balance & cock assembly and the frok in last two images, so you can check if horns of the fork are spaced wide enough for impulse jewel or if the horns need a polish.

Long gurad pin might cause the issue you are encountering. 

Just my two cents. 

Good luck 

 

 

Just now, Nucejoe said:

I have lost the luxury of watching videos ( disconnected vpn ). 

You own tests and analysis are sound, you are very close to the location of the fault. 

You show the balance & cock assembly and the frok in last two images, so you can check if horns of the fork are spaced wide enough for impulse jewel or if the horns need a polish.

Long gurad pin might cause the issue you are encountering. 

Just my two cents. 

Good luck 

 

 

Oh , oil the impulse jewel. 

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Something is definitely catching. I agree with your conclusion, that there is unwanted contact between the balance and pallet fork, when the impulse jewel is between the horns. Look more closely at the guard pin. Is it fouling the safety roller?

I think you will find this interesting: https://web.archive.org/web/20080622201835/http://www.timezone.com/library/horologium/horologium631673198118416858

2 minutes ago, Nucejoe said:

oil the impulse jewel

Usually not. Why in this case?

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It seems unlikely but ..... All the ETA's I have, the pallet fork is a simple finish. Yours has chamfered edges and polished. It looks like it's from a more high-end movement.  Could it be the wrong pallet fork ?

There's a walkthrough of a 2472 here https://www.watchrepairtalk.com/topic/4422-eta-2472-service-walkthrough/

and the fork looks like this :    

image.png.00557b6fd2d48caf4562769904baacf4.png

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15 minutes ago, mikepilk said:

It seems unlikely but ..... All the ETA's I have, the pallet fork is a simple finish. Yours has chamfered edges and polished. It looks like it's from a more high-end movement.  Could it be the wrong pallet fork ?

There's a walkthrough of a 2472 here https://www.watchrepairtalk.com/topic/4422-eta-2472-service-walkthrough/

and the fork looks like this :    

image.png.00557b6fd2d48caf4562769904baacf4.png

I was thinking the same. Never saw a decorated pallet fork in any ETA movement. It looks beautiful though.

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55 minutes ago, mikepilk said:

Could it be the wrong pallet fork ?

I agree, this looks suspicious. In @VWatchie's walk-through the pallet fork isn't chamfered either. Coincidentally I just realized I have another watch with a 2472 in it. I'll check the pallet fork in that and try swapping.

3 hours ago, Klassiker said:

Look more closely at the guard pin. Is it fouling the safety roller?

I think you will find this interesting: https://web.archive.org/web/20080622201835/http://www.timezone.com/library/horologium/horologium631673198118416858

Will have a closer look at the guard pin tonight. Thanks for the link, that's a very illuminating read! Sounds like "notch" is the correct term for the space between the horns.

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15 hours ago, fellerts said:

(no oiling of the train) it still wasn't running great: <200° amplitude and inconsistent beat error.

What are you using to measure this  timing app timing machine and it be nice if we had a picture of that if it is a timing machine. Then no oil on the train what about the escapement?

It would be nice to have a picture of the escape wheel in and the pallet fork so we could see how the escape wheel teeth line up with the pallet fork.

Then it's really hard to tell in the video but it almost looks like the pallet fork is too high up and maybe rubbing on the safety roller but I just can't tell from how fast the video plays by and just isn't enough detail.

 

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5 hours ago, Klassiker said:

Something is definitely catching. I agree with your conclusion, that there is unwanted contact between the balance and pallet fork, when the impulse jewel is between the horns. Look more closely at the guard pin. Is it fouling the safety roller?

I think you will find this interesting: https://web.archive.org/web/20080622201835/http://www.timezone.com/library/horologium/horologium631673198118416858

Usually not. Why in this case?

I suspect the fork might need a polish ( rough surface ) so lets see if he gains some amplitude by oiling. 

As spotted the fork might  be a wrong one. 

Rgds

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I wouldn't assume the fork is the wrong one. OP's movement seems to be older than the one in the walkthough; his movement has banking pins, where the other has the bankings stamped in the plate. The fork cock has a nice grained finish too, not really high end, but nicer than the other. If it was intended for a high grade brand, Nivarox could supply different levels of quality on the escapement. I've seen beveled forks in some older ETA, also in some AS (spectacular, Patek level).

 

With a microscope you can usually get an angle where you can pretty much see what's going on. If it's the correct fork there's no way the jewel is hitting the bottom of the slot (notch), unless of course the balance/ roller isn't original.

 

Fredrik- to me if you can see that the roller jewel isn't making contact with the fork horns (?), you can see if it's hitting the bottom of the notch. In running, the roller jewel never makes contact with the horns- those are a safety feature to prevent unlocking at the wrong time. The roller jewel makes contact with the sides of the notch, to unlock and then receive impulse from the escapement. The freedom of the jewel in the slot is around 0.01mm, so very small. On that note, depending on how the watch was treated in the past, there can be a buildup of "stuff" for lack of a better term on the sides of the fork notch. I've seen dramatic improvement in performance in watches that seemed pretty perfect except for crap amplitude by examining the notch under microscope and scrubbing the sides of the notch with pegwood. Similarly you can find stubborn deposits on the sides of the roller jewel. My gut says your issue lies around there.

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7 hours ago, nickelsilver said:

On that note, depending on how the watch was treated in the past, there can be a buildup of "stuff" for lack of a better term on the sides of the fork notch. I've seen dramatic improvement in performance in watches that seemed pretty perfect except for crap amplitude by examining the notch under microscope and scrubbing the sides of the notch with pegwood. Similarly you can find stubborn deposits on the sides of the roller jewel. My gut says your issue lies around there.

I think you are bang on here. I took the pallet fork and balance to the jar of naphtha with a brush for the third time, and now finally the balance is moving the pallet fork seemingly without undue resistance! I have a fairly powerful microscope and the surfaces looked spotless before cleaning them. Wow, I have newfound respect for what "clean" means, and I'll be sure to remember that for future tinkering.

7 hours ago, Nucejoe said:

I suspect the fork might need a polish ( rough surface ) so lets see if he gains some amplitude by oiling

The surfaces that actually matter are in fact polished. Perhaps they could be even smoother though.

IMG_3401.thumb.jpg.50ea1f00f8f43c9a0d12bbf6b9352f33.jpgIMG_3399.thumb.jpg.eaed1a5d218b80f427eddbc57472d058.jpg

While investigating I also compared the horn to the impulse jewel. To me it looks like the proportions line up and that there is enough clearance for the impulse jewel to rest in the horn. The guard pin does not foul the safety roller and neither do the horns, by the way.

IMG_3396.thumb.jpg.721ead10e83900438b42c161c7559c69.jpg
 

9 hours ago, JohnR725 said:

What are you using to measure this  timing app timing machine and it be nice if we had a picture of that if it is a timing machine. Then no oil on the train what about the escapement?

It would be nice to have a picture of the escape wheel in and the pallet fork so we could see how the escape wheel teeth line up with the pallet fork.

Unfortunately the timing graph tells me that I have yet more problems to tackle (here is DD then CR on a full wind):

image.png.89461268fa806f27771426e645d2eb07.png

image.png.227e3f03a35d6c9517f9d7da3cd954a7.png

The train s still bone dry here. The escape wheel has a capped bottom jewel which I oiled. The balance cap jewels are also oiled. If the movement was clean and in perfect condition, I would get satisfactory results without oiling the train, right?

I'm flying away to see family for Christmas tomorrow, so I won't be able to work on this until next year. When I'm back I'll give the whole movement a 2nd clean and then look closely at the escapement next.

Thanks for all your help guys!

 

Edited by fellerts
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28 minutes ago, fellerts said:

Unfortunately the timing graph tells me that I have yet more problems

By the way you still haven't answered one of my questions I wasn't talking about the train for lubrication. The waveform going straight across looks a bit rough if somebody forgot the oil there escapement that specifically the pallet stones you will get an effect just like this. Even if you oil the escapement and like one stone is dry you can see it in the timing graph so if you don't oil the escapement you will see it will look war and you will not have amplitude. But yes when you switch the crown position your definitely losing power I would still oil the gear train oil with anything a half I don't care what you will with oil with Just about anything I don't really care but there should be oil on the train and definitely oil on the escapement that's the pallet fork and escape wheel

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46 minutes ago, JohnR725 said:

Just about anything I don't really care but there should be oil on the train and definitely oil on the escapement

Okay wow, you are absolutely right. After oiling the train with 9010 and the pallet stones with 9415 (DD then CR)

IMG_3405.thumb.jpg.0659da7a02ce3d825479995fef4e5f9e.jpg

image.thumb.png.17950ebbd2896d385f7a30885383a7fa.png
 

Apologies for my ignorance. I appear to have misunderstood all the reasons why we oil a movement.

I really love this hobby. It seems rather simple on the face of it, but there are so many facets to everything. Thanks again @JohnR725.

Now I really have to start packing...

Edit: I don't know the correct lift angle for this movement so the numbers might lie. I'll look that up and do some proper testing after 24 hours when I'm back.

Edited by fellerts
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On 12/22/2022 at 1:50 PM, nickelsilver said:

I've seen dramatic improvement in performance in watches that seemed pretty perfect except for crap amplitude by examining the notch under microscope and scrubbing the sides of the notch with pegwood. Similarly you can find stubborn deposits on the sides of the roller jewel. My gut says your issue lies around there.

Another golden tip! Many thanks!

So I guess it's just a matter of carving a flat side on a piece of pegwood to the appropriate size and scrubbing on? Would the same go for the roller jewel?

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34 minutes ago, VWatchie said:

So I guess it's just a matter of carving a flat side on a piece of pegwood to the appropriate size and scrubbing on?

Whatever you do you want to be extremely careful and definitely don't bend the guard pin. But it's amazing what you can find in books here's a recommendation's I snipped out an image for you. Then yes you don't have to agree with everything found in a book as this makes me very nervous.

pallet fork slot polishing.JPG

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7 hours ago, Nucejoe said:

Wouldn't that affect the lift angle? 

That's a good question. Then if somebody gets really aggressive making that slot bigger a lot of roller jewel's can't be made bigger because the whole legal in isn't big enough. There is some watches were the roller jewel appears to be pressed in there be no way that you could change the size. Which is why I try to stay away from things like this. Other than I've seen it in the books that it can be done.

Then I'm not really sure I was going to agree that yes it would but looking at the image I not sure it changes the angle. But I'm sure if you didn't get it perfect it would screw things.

lift angle witschi definition.JPG

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  • 2 weeks later...

Happy new year folks!

I'm finally back at my desk and have started fiddling with this movement again. After giving it a full wind and regulating it a bit, I noticed that the amplitude DD kept climbing... and climbing... until it stabilized at around 340 degrees! At this point I'm worried the impulse jewel is going to swing around and crash into the pallet horn. Ref. this thread, Is that what "rebanking" means? I watched it on the timegrapher for a while longer until the following occurred with no provocation from my end:

image.png.e67dc79054dc58310ad4ca1368b14a46.png

Should I re-title this thread "high amplitude - impulse jewel fouling pallet horn"? 🤣

In all seriousness though - I couldn't really discern any "galloping" sound from the movement when this was happening, but note that it runs rather quiet so it's hard to be sure. Could the mainspring be too strong for this movement? I did not replace it as it looked fine, just cleaned and lubricated it. This is the first automatic I've ever held so I'm not sure how it should feel when the mainspring starts slipping in the barrel, but I can say that the friction increases slightly at some point. 

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25 minutes ago, JohnR725 said:

What happens if you run the watch crown down how does things look there? Because yes it looks like too much amplitude.

Crown down gives 250 degrees. I haven't wound it in 1.5 hours and DD still gives 340 degrees.

Here's a picture crown down: image.png.4b9a09652796e56b67ea89716042100a.png

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On 12/22/2022 at 4:20 PM, mikepilk said:

As an aside - @Nucejoe, is it worth polishing the insides of the forks to gain amplitude ?

Hi Mike, I didn't notice your comment is actually a question, hence my late response.

Here we see how cleaning the fork affected amplitude. 

 All previous discussions tend to emphasize on oiling pallet end of the fork,  the horn side plays an important role too, its where the force of impulse is to get transfered, so whenever I see low amplitude I check the fork horns under good magnification and usually end up polishing the horn side anyway.

What I don't understand is; how is it that oiling pallets is so emphasized on but oiling impulse jewel isn't.  

Rgds

 

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6 hours ago, Nucejoe said:

What I don't understand is; how is it that oiling pallets is so emphasized on but oiling impulse jewel isn't.  

 

Very good question. I'd like to know the answer.

13 hours ago, fellerts said:

Crown down gives 250 degrees. I haven't wound it in 1.5 hours and DD still gives 340 degrees.

Here's a picture crown down: 

340° is much higher than you want - you will get rebanking for sure.

How is it DU ? I recently installed a new staff and got too high an amplitude as one end of the staff wasn't rounded (it had a little 'nipple' on). 

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