Replacing Broken Pocket Watch Jewels

[bbodnyk]

Ideally when repairing one of these old American pocket watches any broken jewels should be replaced. However I'm wondering with the scarcity of parts whether sometimes one can let a cracked jewel remain?

If a jewel has a simple crack, no chips and the force of the driving wheel pushes a pivot against the "good" portion of a jewel then there should be no damage to the pivot by letting the cracked jewel stay in the watch. Am I correct in thinking this?

Thanks!
Bruce

[richiec]

It would seem to me that if you were wearing the watch, the load would vary from one area to another and any shock could cause the crack to enlarge or shatter the jewel. A good watchmaker should be able to rejewel it but it may require it to be rubbed in or reset which would require a careful match of color so the repair is unnoticeable. All depends on how much you have to spend and how often the watch is used. In any event, the watch may not keep good time with the crack when worn. Just my 2 cents.

[bbodnyk]

As long as a watch is not being subjected to shock loads I would think that as long as there is force from the mainspring each pivot in the main train should have a point of contact with its hole that ideally should not vary which is why pivots of lower jeweled watches wear into the sides of the holes. My point is that if the direction of force is against the unbroken side of a jewel than no damage should be done to the pivot.

I would agree that a cracked jewel is apt to crack more which is reason to change it I expect.

[Tom Huber]

Bruce, A couple of years ago I restored an early AWCo model 57, AT & Co. This one has the large clear "Liverpool windows" type jewels on the top plate. Both the third and fourth wheel jewels in the top plate had a crack. After restoration, the watch runs and keeps time with these cracked jewels. I could have changed the jewels, but could not find jewels to match the other two in the top plate. To keep the cosmetics of the matching jewels in the top plate, I elected to leave them alone.

Tom

[RJSoftware]

I know the answer to my question on this is an obvious no. But I wonder if a jewel being cracked would not benefit from super glue.

If one was careful enough to peg out the excess glue, I could imagine that the crack would be bonded secure in many situations.

Not speaking about a crack with missing chunk but a hairline type.

RJ

[RJSoftware]

...

[richiec]

It may be hard to make sure, without a microscope, that the jewel is perfectly concentric and the staff wouldn't bind on it. Just a thought. Super glue is hard to work with to begin with and it may grab a piece of the wood you are using to peg the jewel out and bond it to the jewel. Maybe leave it alone and do what you first intended to do.

[bytes2doc]

Is there a source were you all can still find jewels?

Are newer synthetics being made and available?

Would love to see a discussion on just how you all measure those holes - special gauge?

thanks

[Vacheron]

Bruce, A couple of years ago I restored an early AWCo model 57, AT & Co. This one has the large clear "Liverpool windows" type jewels on the top plate. Both the third and fourth wheel jewels in the top plate had a crack. After restoration, the watch runs and keeps time with these cracked jewels. I could have changed the jewels, but could not find jewels to match the other two in the top plate. To keep the cosmetics of the matching jewels in the top plate, I elected to leave them alone.

Tom

I have to agree with Tom. If the jewels are readily available, then it is wise to change them but when trying to find 'specials' like the clear Liverpool's it probably isnt .

[Smudgy]

The friction fit type are commonly available (usually under the brand name Seitz). The rub-in type are harder to find, and many people hoard them because of the difficulties of finding them. The rub-in type can sometimes be found in bulk lots that are being re-sold from a retiring watchmaker. Lately people have gone to using a friction fit jewel in a made setting to make the stone fit the watch, which isn't so bad if the stone can be set without altering the plate (but that won't work on a stone rubbed directly into the plate, which will require the plate be altered). The Liverpool type are nearly impossible to find, so it if you need some you may want to make your own (George Daniels describes the process in 'Watchmaking').

I think all of the new jewels are made from the synthetic rubies.

To measure the holes, the best thing is to make a set of plug gauges. That way you get good at making pivots and you have a useful tool when you are done.

[Dave Haynes]

It is not uncommon to have a crack in the jewel, but you had better really look close at the hole since if it is rough in the least, it will eat a pivot in short order. I used to have a complete set of Bergeon hole gauges, but like a fool sold them. I usually take the wheel and put it into a pivot gauge (which are a lot less to buy) to determine the jewel size.