Jewelling question

[bsoderling]

When cleaning a movement in my ultrasonic a jewel in one of the bridges came out and needs to be put in again using my not so often used Seitz set.

 

When inspecting the hole I note a couple of tiny (maybe 1/4 of the hole diameter)circles at the edge that I started to suspect may come from a previous trial to tighten the hole just slightly with a punch around the hole edge.

 

I have attached a photo that I hope shows what I think can be the punch marks.

 

Would this be an ok method to tighten the hole and something I can repeat as I guess the jewel will not sit very safely when pressed in again?

 

When viewed from the top side, I note that the hole is lined with a brass ring that doesn’t go all the way through. Why were these brass linings used? Softer material?

 

 

 

 

 

 

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[nickelsilver]

Can you post a pic of the other side? Sometimes on normal grade pieces they were retouched around the jewel hole after plating to show the brass and give the impression that the jewels were set in chatons.

Hard to tell if a previous attempt was made to close the hole. You can try a domed (convex) punch to close it a little. Try a punch where the round face is about 50% bigger than the hole. I like to do a little from both sides.

[bsoderling]

Hi,

Photos are attached and I think you are probably correct. Looking closer, what I thought was a boundary between the chaton and the bridge inside the hole, probably is just the edge between plating and brass.

Hopefully you can judge from the photos?






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[rodabod]

I'd use Nickelsilver's suggestion of closing using a domed pusher in your jewelling set.

[nickelsilver]

18 hours ago, bsoderling said:

Hi,

Photos are attached and I think you are probably correct. Looking closer, what I thought was a boundary between the chaton and the bridge inside the hole, probably is just the edge between plating and brass.

Hopefully you can judge from the photos?






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Yes, those are "fake chatons". The bridge itself is made to look like it's 3 separate cocks. What's interesting is some makers went through such efforts to make the product look more high-end, while it was fairly certain the only person to ever see the movement would be a watchmaker.

[rodabod]

I think the "fake chatons" and general attempts to show off generally dates to earlier in the century when customers were more likely to see the watch movement in the shops, especially if it was a shop-built watch made to order. It was common back then to choose a particular movement and have it mounted in a standard caselike a Dennison model, for example.

One other thing you sometimes see is an enlarged cap jewel which is visible when looking at the balance cock, yet the cap jewel fitted to the plate is much smaller. Purely cosmetics to "wow" the customer.

Then in the 1970's we have the fight for maximum jewel count, with superfluous cap jewels everywhere.

[bsoderling]

One thing is sure; human behavior never seize to amaze...

A quick update on my progress.

I decided to fit the jewel without trying to reduce the hole first, just to see how loose it would be. When pushing the stone in, after a bit it suddenly shatters in small pieces. I suspect there was an edge or burr or something that pinched too hard at some local point.

Almost caved in at that point but decided to have a look around some other less fortunate movements in my drawers. And indeed, an old pin pallet movement I never got to run had a jewel with the same dimension and this time the pushing-in worked better and the jewel seem to sit safely.

Regarding the technique to reduce the hole with a domed punch, I suppose one has to be very light handed to not overly deform the edge of the hole too much?

As I see it, all the force from the punch will be focused on that tiny area where the dome meets the hole corner. I suppose what one wants is to have material deeper into the hole to expand and reduce the diameter, without creating burrs and deformations on the edge?



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[rodabod]

The action of the punch (pusher) is possibly best shown by Seitz' own drawing:

 

[bsoderling]

Cool...!

Thanks !


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[rodabod]

One thing to check (which you may have already done) is the hole size (which then corresponds to side-shake) when you selected the new jewel. You can simply take the relevant wheel and sit its pivot in the new jewel hole and observe the angle which the pivot is permitted to move from side to side. You can judge this by eye.

[bsoderling]

I think I did pretty much that. As you say, wiggling the jewel on the pivot is a decent way to ensure there is a reasonable side shake. Good to know it’s used by others.




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