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margolisd

Pallet Stone Wear

Question

Hi folks. Ive got an Omega that's showing occasional beat errors in certain positions and only on one side. It's very intermittent and I can't work out what's causing it. Because it's just on one half of the reading (lower) it made me think one of the pallet stones could be damaged or dirty. I just put them both under the microscope to see how they're looking. Is this a normal amount of wear for a 50 year old watch?

 

 

 

 

stone2.png

stone3.png

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34 minutes ago, margolisd said:

Just out of interest, is there any reason we don't use synthetic diamond as pallet stones?

I'm sure there are some oddball watches out there with diamond pallets, Harrison's H4 for example had them (and Derek Pratt's replica of that piece) but that's really a unique example.

Diamond is about 4 times harder than corundum (sapphire, ruby). That means that is can be used to fairly easily work corundum. But diamond can only be worked with diamond, and it's a slow process. Raw material wise the corundum is cheaper, and add to that the much lower manufacturing cost of jewels, and that generally corundum has a very good- almost indefinite- service life when used with steel, should explain it.

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Thanks Praezis. Do you think I should replace the fork?

Can you tell me more about the weak release noise? I've not come across this before. Does this mean I need to increase the sensitivity of the machine?

 

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3 hours ago, margolisd said:

Hi folks. Ive got an Omega that's showing occasional beat errors in certain positions and only on one side. It's very intermittent and I can't work out what's causing it. Because it's just on one half of the reading (lower) it made me think one of the pallet stones could be damaged or dirty. I just put them both under the microscope to see how they're looking. Is this a normal amount of wear for a 50 year old watch?

 

 

 

 

stone2.png

stone3.png

     it looks like wear,  can you measure it?

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4 hours ago, margolisd said:

Thanks Praezis. Do you think I should replace the fork?

Can you tell me more about the weak release noise? I've not come across this before. Does this mean I need to increase the sensitivity of the machine?

 

Hi,

you can replace the fork, but it is no must imho. There is a good chance then that you have to adjust the pallets, too. 

What I wanted to say, you probably have a measuring issue, no mechanical issue - my experience with developing timing machine software.

In short: a tic noise consists of 3-4 single noises, the first being the weakest, but used for timing. More on tic noise you will find in the software TM threads on this forum.

Frank

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Hi  The enclosed PDF's are from Witschi training bulletins and explain the tic/toc issue with the escapement regarding the sounds picked up on their timing machines. They may be of some use to you in understanding the action of the fork and impulse jewel on the roller

Witschi Training Course (2).pdf Test and measuring technology mechanical watches.pdf

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1 hour ago, anilv said:

If the pallet stones are worn then the escape wheel is probably worn as well, changing one without the other doesn't make much sense.

Have you fitted a new mainspring? If not that is what I would replace first.

Anilv

Yes, yes yes, The cause in faulty escapewhell teeth, no oil will remedy.  

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When it comes to the pallets, the only part that should be oiled are the pallet stone faces. Never oil the pivots of the pallets as it will cause drag and the movement will fail to keep time. You must use the correct oil for the escapement, if you are not sure which; look for one that specifically says for watch escapements. Some watchmakers prefer to oil the teeth of the escape wheel and let the combined action of pallets and escape wheel to distribute the oil. Pallet stones should be smooth on their face, any marks, chips and they should be re-placed. The stone is harder than the escape wheel so it is most likely it also is worn.   

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9 hours ago, margolisd said:

Interesting. I normally use a little 9010 on the pallet cock jewels :phew:

Thank you marg for sharing, I had just heard about it, never seen an actual case and them pallets jewels sure tell the story. Regards 

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7 hours ago, anilv said:

If the pallet stones are worn then the escape wheel is probably worn as well, changing one without the other doesn't make much sense.

Have you fitted a new mainspring? If not that is what I would replace first.

Anilv

Yes, this occurred to me. The stone is much harder than the escape wheel so it would make sense that it is even more worm. I've ordered both. Yes, the mainspring has been changed as well :) 

17 hours ago, praezis said:

What I wanted to say, you probably have a measuring issue, no mechanical issue - my experience with developing timing machine software.

You could be correct. I'm going to replace the pallets anyway so we'll find out. But thanks for enlightening me on this subject as it's not something I've read about so far.

1 hour ago, oldhippy said:

When it comes to the pallets, the only part that should be oiled are the pallet stone faces. Never oil the pivots of the pallets as it will cause drag and the movement will fail to keep time. You must use the correct oil for the escapement, if you are not sure which; look for one that specifically says for watch escapements. Some watchmakers prefer to oil the teeth of the escape wheel and let the combined action of pallets and escape wheel to distribute the oil. Pallet stones should be smooth on their face, any marks, chips and they should be re-placed. The stone is harder than the escape wheel so it is most likely it also is worn.   

Thanks OH. My process is:

Clean.

Epilame the escape wheel and the pallet jewels (the jewels only)

I oil the balance end stones with 9010.

I have always used a spot of 9010 on the escape pivots and the fork pivots just to moisten them. I get the feeling this is a divisive issue! I guess I'll stop doing this.

Assemble and let it run dry for a good few minutes.

Finish by putting a little 9415 on the pallet stone faces.

 

Thanks all for the advice. Super useful as ever!

 

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I suspect because a synthetic diamond of that size would be pretty expensive. Small industrial diamonds used as abrasives are dirt cheap, but flaw free synthetic diamond is still rather expensive. Synthetic ruby (crystalline aluminium oxide) is much easier to produce, and almost as hard as diamond. 

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You could also use something like silicon carbide or boron nitride, if hardness was the only consideration, but there is a trade off between price, hardness and ease of manufacture.

The steel should in theory wear out long before the sapphire does, but that does not take in to consideration the ingress of dirt, which may include tiny particulate matter from the environment, the watch manufacturing process, and any cleaning that has been done over the years.

If a tiny piece of silicon carbide manufacturing dust, or an industrial diamond shard from a cleaning cloth was impregnated in one of the teeth of the escape wheel for example, or was introduced in contaminated oil,  it could slowly, over many years eat away the surface of the palette stones. Dirt, as you are no doubt aware is one of the major killers of watches. You can find highly abrasive dirt pretty much anywhere in our modern industrialized world.  You may find this interesting.

 

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Theoretically you could swap them, but you would need to be able to re-fix them with shellac with a high degree of precision. The tooling is available to do this, and most watch repair books describe the process.

I suspect however that you can pick up a replacement complete fork for a lot less than the cost of your time.

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