My first attempt refitting and adjusting pallet stones using shellac

[JohnR725]

Yes it would be better if you could leave the jewels where they are and just move them around. Just a reminder the stones are slightly different angle and you don't want to mix them up. Plus of course you don't want to misplace one as that would be a new fork.

[Endeavor]

5 hours ago, JohnR725 said:

Just a reminder the stones are slightly different angle

An important piece of info I didn't know ! Currently both Miyota jewels are floating in the same jar, so it's going to be a kind of 50/50 . The good thing is that the Miyota was a scrap movement ....... I guess that's the reason for trials, valuable lessons are to be learned ! Thank you very much for your input

BTW; I like your wording; "misplace"

Edited August 6, 2022 by Endeavor

[VWatchie]

On 8/6/2022 at 7:32 AM, Endeavor said:

In case of the Omega 861, where the entry-jewel is deemed to sit slightly too deep, instead of stripping the whole fork wouldn't it be wiser to just warm the fork, melt the old-shellac and try to push the jewel in a bit further?

I believe that's what the professionals do. Personally, I like to do one small step at a time for maximum control. Trying to adjust the stones with the shellac in place I worry I might make a mess, but perhaps I'm overly worried. Perhaps the risk of losing a stone and the additional work of removing the old shellac isn't really worth it. Of course, if the old shellac has deteriorated to the point it's starting to fall apart, which it is not in your case, it needs to be replaced anyway.

On 8/6/2022 at 9:22 AM, JohnR725 said:

Just a reminder the stones are slightly different angle and you don't want to mix them up.

 

On 8/6/2022 at 10:08 AM, Endeavor said:

An important piece of info I didn't know ! Currently both Miyota jewels are floating in the same jar, so it's going to be a kind of 50/50

No worries! The difference in angle is absolutely visible. The angle of the impulse surface on the exit stone is quite a bit steeper than that of the entry stone. Have a look at the third and fourth images in the below-linked post. If you place the stones side by side you will clearly see the difference.

 

Edited August 8, 2022 by VWatchie
clarification

[Endeavor]

After circling around and around it, I finally adjusted the pallet-jewels of my 1975 Omega Speedmaster Mark II.

Inspired & guided by this article, and after having had a huge learning curve replacing "Garnet"-jewels for modern (too small, too low) jewels in a 120 years old pocket watch, I decided it was time to tackle the job.

There are many valuable tips in this article and all I like to do is to share a few of my experiences.

Like VWatchie, I also found that Acetone is a very effective way to remove the old shellac, more effective than industrial isopropanol. Acetone is widely available, no need to look further than your wife's nail-polish remover.

In my case the Acetone turned to old shellac in a white transparent substance, which later, while cleaning the fork-slot, caught me out. I simply didn't see it and hence the fork-slot wasn't cleaned properly.

As for applying the shellac; I tried the "pulling strands on peg-wood"-method and the "creating small balls"-method. To me, the "small balls"-method worked the best. If the size of the ball is too big, one can "nibble" it down with some fine tweezers.

As for the ease of adjusting the depth of the jewels, again I came to the same conclusion as VWatchie. For me it worked far better, and far more relaxed to adjust the jewels without the Shellac applied. As VWatchie said, hopefully there is enough friction between the jewel and the fork-slot to keep the jewel in place for testing. When Shellac is applied, one has to melt it, do the adjustment above a hot plate and there is time-pressure. Plus, without the Shellac, it became for me far more easy to see if the jewel had moved or not. Adjusting the jewels became for me far less cumbersome when done without Shellac.

As for melting the Shellac; initially I used a timer, to get an idea of how long it took for my alcohol burner / pallet-fork heater to get to the Shellac melting-temperature. That worked fine one day, not the other. The alcohol-burner I'm using is not producing a consistent heat and when heating 1 minute was fine on the day, it totally melted the Shellac to "water" on the next. The method I'm using now is to place the Shellac ball on the end of the fork-slot and heat the pallet heater above the flame, performing checks on very regular intervals. One sees the Shellac-balls slowly melting and continues until your are happy with the distribution. If the size of the Shellac ball is slightly too big, you stop before it flows out too far. If the ball is slightly too small, you just heat somewhat longer until it flows out far enough.

As for adjusting the jewels; one can use brass tweezers to push the jewels, from the rear, further out of the fork-slot, but I used peg-wood to push the jewels back in. I did some adjustment testing on junk pallet-forks and when using steel tweezers, the chances that you chip the impulse-plane or the back of the jewel, are very high. With steel-tweezers I had a 100% chip-score with the jewels of both test forks.

One very important "adjustment"-lesson I've learned from @nickelsilver; if you move one jewel, it affects the other: https://www.watchrepairtalk.com/topic/23176-1975-omega-861-amplitude-after-24hrs/#comment-196690 .

It surely does !!

Many thanks to VWatchie for penning this thread and thanks to @nickelsilver and @JohnR725

 

 

 

 

Edited January 10, 2023 by Endeavor

[VWatchie]

Congrats @Endeavor and thanks for sharing experiences made, much appreciated 

Now, it's going to be truly interesting to hear what this manoeuvre did for the amplitude!?

Edited January 10, 2023 by VWatchie

[Endeavor]

Well, sadly that was not the only problem. The Omega 861 has a common problem, the wear around the main-spring barrel, as @nickelsilver mentioned here; https://www.watchrepairtalk.com/topic/23176-1975-omega-861-amplitude-after-24hrs/#comment-196628

Sure enough, look at the wear marks inside the barrel bridge and top of the ratchet wheel ..... sigh

It seems however, that the arbor / barrel-play takes a big part of the blame ..... not that difficult to correct.

The arbor / barrel-bridge, if required, is another challenge (I don't have the equipment for the "bushing-trick", so perhaps to ream out and inserting a jewel?)

 

 

Edited January 10, 2023 by Endeavor

[JohnFrum]

Here copper circuit stripboard and a soldering iron are used. 

 

[nickelsilver]

It's normal to see some wear marks where the ratchet wheel contacts the bridge. As it is just floating there it does make contact- I put a little grease there but it's often dry. You'll need to get a good look at the barrel pivot hole in the bridge and plate, look from the inside with some backlight, the pivot usually doesn't make it all the way through, so it can look round and nice from the outside, but egg shaped from the inside.

[JohnR725]

4 hours ago, nickelsilver said:

It's normal to see some wear marks where the ratchet wheel contacts the bridge. As it is just floating there it does make contact- I put a little grease there but it's often dry.

I think technically it's supposed to float above the main plate but I would agree typically you'll see wear it has touched. Then exactly what you're doing I will put grease anyplace I see that parts are wearing. I also like to check any of the steel components like ratchet wheels to make sure that there is no burrs on the edges of the teeth because sometimes that happens and that's why you'll see the wearing. 

5 hours ago, Endeavor said:

so perhaps to ream out and inserting a jewel?)

Usually they put bushings bushings in as it's hard to get a jewel of the correct size to fit.