Setting A Roller Jewel Without Special Tools

James Wrobel

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Jan 17, 2020
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I needed to set a roller jewel without the special tools to remove the roller plate and heat it. I didn't want to heat the whole balance, so I had to improvise.

Essentially, I dissolved shellac in isopropyl alcohol to make a glue-like solution. It took two days and some experimentation to obtain the consistency that I wanted. I used about 1ml of alcohol and 1g of shellac flakes ground into crystals, but I need to be more precise about that (see below). I set the jewel with this mixture and also a test bead. Then I blew air over the balance at about 90 deg F to help evaporate the alcohol. After one hour, the test bead was set and the jewel was tight.

Does anyone know of a problem with this method, or maybe a precedence for it? It may not be of much use to the watchmakers who have the tools, but it was essential for me.

If useful, I know that the glue making formula can be improved and better documented.

Thanks,
jjw
shellac_paste.JPG
 

gmorse

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Hi James,

I think this method is perfectly valid as long as the pin doesn't move during the drying process. That's the advantage of warming the straight shellac to melt it, it sets very quickly as it cools down. Using warm air to speed up the evaporation of the alcohol is fine, but it should just be warm, not too hot or you'll melt the shellac.

Regards,

Graham
 
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James Wrobel

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Yes, you’re right, and it did move on me. But I think I can improve the mixing and drying processes, and I’m confident I can get this to work. I will experiment with the drying temp as well.
Thanks,
jjw
 
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James Wrobel

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Jan 17, 2020
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I'm happy to report that, after several tries, I was able to set the roller jewel with cold shellac paste, and the watch is running well. The several tries were not due as much to the shellac as to the fact that I had never set a roller jewel before, and I was pretty clumsy at it. Whoever invented the D-shaped hole in the roller plate was a genius, but mine is round, and allows too much freedom.

I was able to acquire several important tips for the next time I do this:
1. Crushing the shellac flakes into powder is essential to getting a good smooth mix in much less time.
2. Whatever container is used I would add enough alcohol to just cover the shellac powder. I used an eye dropper. This produces a solution which is too thin at first, but it mixes well and is smooth. I got some approximately 1/2 ounce hard plastic containers (as illustrated above) at the craft store. These worked well and can be cleaned.
3. I let the shellac dissolve for about one day, mixing it occasionally with a toothpick. I then let it sit for about another day (uncovered) to thicken. I'm sure this whole process can be quickened with a little warm air, but I didn't do this.
4. I found the ideal thickness to be about equivalent to white school glue. I applied it with an oiler. The jewel set for me, and did not move.
5. If the jewel does move (and it did the first time), I just immerse the whole balance in a container of alcohol and put the container in the ultrasonic filled with water. After 20 min the jewel comes right out and I can start over.
6. I hastened the drying process with some warm air at about 90 deg F. This took about 1-2 hours.
7. The shellac ends up dry, but not really hard or brittle. I'm hoping this will prove to be very sturdy.
8. I scraped the excess shellac off the roller table very easily. In my opinion, it left a fairly clean job.

Putting the balance in the ultrasonic (not with alcohol, with cleaning solution) is what made the jewel fall out in the first place. I'm lucky I noticed it missing and found it. I don't think I'll do that again.

Anyway, after being afraid that I might never get this watch back together again, I'm pretty happy.

Thanks,
jjw
 

darrahg

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I applaud your efforts and documenting it for others as well as your success. I tried it years ago and could never get the shellac to hardened sufficiently. It seemed to harden but the roller jewel moved with time. I went back to the heating method for a sure thing and, besides, I didn't want to spend the wait time to complete the job. DA
 

James Wrobel

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Jan 17, 2020
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Thanks. I figured someone must have tried this before.

Well, I'm running the watch in the vise for a while. If the jewel comes loose, I'll let you all know. If the method doesn't work, it would at least be useful that everyone can be aware.

jjw
 
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John Hinkey

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Feb 21, 2022
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Have people tried to glue in the roller jewel with UV cured superglue? It seems that it would allow you to set the jewel and then in a non-contact manner set the glue with a UV light. If a mistake is made acetone (or something else) to the rescue to dissolve the glue and you can start over.
I'm sure I'm not the first to think of this.

I have some parts movements that I ended up not scavenging parts from and two of them have roller jewels that need to be re-mounted. Not having to use shellac would be great . . .

- J
 

karlmansson

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Apr 20, 2013
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Have people tried to glue in the roller jewel with UV cured superglue? It seems that it would allow you to set the jewel and then in a non-contact manner set the glue with a UV light. If a mistake is made acetone (or something else) to the rescue to dissolve the glue and you can start over.
I'm sure I'm not the first to think of this.

I have some parts movements that I ended up not scavenging parts from and two of them have roller jewels that need to be re-mounted. Not having to use shellac would be great . . .

- J
I think the good thing about shellac is that it is very hard and unyielding when set and that's good for a system that relies on mechanical transfer of energy. And at the same time it can be easily re-heated in order to adjust.

As you say, curing with UV glue would require dissolving the glue in acetone to adjust and then start all over. I can't really see how that would be more convenient.
 

James Wrobel

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I think UV glue is an acrylate. I’ve seen warnings in this forum about using acrylates (superglue) because of side effects due to outgassing.

Also, I think UV glue would be more difficult to remove than shellac. Very convenient idea, though.

jjw
 

John Hinkey

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Feb 21, 2022
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I think UV glue is an acrylate. I’ve seen warnings in this forum about using acrylates (superglue) because of side effects due to outgassing.

Also, I think UV glue would be more difficult to remove than shellac. Very convenient idea, though.

jjw
Outgassing doesn't seem to be a problem for UV glue used to hold in watch crystals - I suspect due to the different curing processes.
I have some old/scrap movements with very tilted impulse jewels - I may see if I can get UV glue to work, both gluing the jewel in AND dissolving the glue to remove it if necessary.
I think there is likely a longevity of the mechanical bond issue - since the impulse jewel gets mechanically jolted with each swing of the balance wheel fatigue of the glue joint might be in issue if the bond is too brittle. I suspect shellac is pretty good for fatigue life since it's been successfully used for 100's of years now for such things.

- J
 

karlmansson

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Apr 20, 2013
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Outgassing doesn't seem to be a problem for UV glue used to hold in watch crystals - I suspect due to the different curing processes.
I have some old/scrap movements with very tilted impulse jewels - I may see if I can get UV glue to work, both gluing the jewel in AND dissolving the glue to remove it if necessary.
I think there is likely a longevity of the mechanical bond issue - since the impulse jewel gets mechanically jolted with each swing of the balance wheel fatigue of the glue joint might be in issue if the bond is too brittle. I suspect shellac is pretty good for fatigue life since it's been successfully used for 100's of years now for such things.

- J
I just don't see why? Shellac offers the best of both worlds. It's stiff once set and easily softened and removed. Getting it all off of there is no more complicated than soaking a part in alcohol. Even at that stage less involved than UV-glue, acetone is far nastier than ethanol.
 

John Hinkey

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Feb 21, 2022
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I just don't see why? Shellac offers the best of both worlds. It's stiff once set and easily softened and removed. Getting it all off of there is no more complicated than soaking a part in alcohol. Even at that stage less involved than UV-glue, acetone is far nastier than ethanol.
Oh, for me I have watched many YouTube videos of what's required to replace/repair the impulse jewel (AND pallet jewels which don't look fun to deal with) and it's very intimidating. Also it seems to require special tools, heat, and lots of practice. For me if you can put a dab of thick (low viscosity) UV cured glue in the hole, place the jewel relying on the viscosity of the glue to keep it in place, make sure it's straight, etc. and then just turn on a UV light for several minutes and you are done seems very attractive assuming the UV glue will hold up over time.
Having to soak it in acetone (nail polish remover) or alcohol to soften the UV glue bond to remove the jewel seems like a small price to pay.

Anyways, I clearly have no experience replacing an impulse jewel. If I have time I will give the UV glue route a go with one of my spare PW movements that has a very wonky impulse jewel that needs to be removed, cleaned up and then glued back in place. I'd then let it run for a long time (weeks) and see how well the UV glue holds up.
 

James Wrobel

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Jan 17, 2020
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It's a very interesting approach. I'd like to know if it works.

Setting the roller jewel itself is very difficult. It must be done at about 20x magnification, and getting it straight took me several tries.

As for the pallet jewels, I've been thinking about that, and I'm stumped as to how they can be replaced without the special tools needed to align them perfectly. For now, I would have to rely on an expert. But a cold adhesive process may offer hope of an alternate method. One of these days, I will have a pallet jewel fall off, and I will have no choice but to improvise a procedure. I'm not too anxious.

jjw
 

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