Pallet jewel angles question

[caseback]

Working on my Junghans J49 / Alpina 211, the next hurdle after making the balance staff was getting the pallet fork back together. I made a new staff (cylindrical, so I could adjust the height), and after straightening the bend in the pallet fork body, the fork horns and guard finger got along nicely with the roller and jewel. Next step is replacing the jewels. Both are chipped and the entry jewel is (as Nev pointed out) in fact an exit jewel as well. Obviously length and width need to be ok to get them to fit the fork, but what about the angles? The "Watch Repairer's Manual" has a picture showing 103 degrees for the entry jewel and 115 degrees for the exit jewel. Cousins doesn't show angles for these jewels, only the size. Does that mean the 103 and 115 degrees are "standard"? That would be easier then having to grind them to a specific angle..

[nickelsilver]

On vintage stuff Seitz replacement pallet jewels are fine. I just measured a couple and got 102 for entry and 114 for exit, pretty close to what Fried wrote.

 

Sometimes the length is an issue, too long and it can be trimmed on the back side, too short and they can still work but are unsightly with a large gap at the back of the slot.

 

On rare occasions I have lapped the face to change the angle slightly, but only on really nice pieces that merited it.

 

Practical Benchwork for Horologists by Samuel and Louis Levin shows a nice way to accurately lap the face on page 196 (link is to an archive.org copy of this awesome book).

Edited October 5, 2024 by nickelsilver

[caseback]

1 hour ago, nickelsilver said:

On vintage stuff Seitz replacement pallet jewels are fine. I just measured a couple and got 102 for entry and 114 for exit, pretty close to what Fried wrote.

 

Sometimes the length is an issue, too long and it can be trimmed on the back side, too short and they can still work but are unsightly with a large gap at the back of the slot.

 

On rare occasions I have lapped the face to change the angle slightly, but only on really nice pieces that merited it.

 

Practical Benchwork for Horologists by Samuel and Louis Levin shows a nice way to accurately lap the face on page 196 (link is to an archive.org copy of this awesome book).

Thank you! I have a small Seitz assortment and a lot of vintage loose parts so I should be able to find a replacement. 

[nickelsilver]

I heard through the grapevine recently that Bergeon has re-stocked the Seitz lineup of jewels across the board- over the last few years suppliers have offered fewer and fewer refs, marking them as "discontinued". I hope that the news is true!

[caseback]

11 minutes ago, nickelsilver said:

I heard through the grapevine recently that Bergeon has re-stocked the Seitz lineup of jewels across the board- over the last few years suppliers have offered fewer and fewer refs, marking them as "discontinued". I hope that the news is true!

Fingers crossed!

30 minutes ago, nickelsilver said:

I heard through the grapevine

It took me by suprise I must say..

[nevenbekriev]

OK, I see You advance with the project. It will be no surprise to me if You will perfectly adjust the escapement from the first attempt, I have such feeling.

Yes, the pallets stones angles are pretty standard and even if the replacement pallet  angle is not exact mach, usually good enough compromise is possible to do in adjustment that will give good result at the end.

First, You need to correctly adjust the banking pins, and for making this You will need to be sure that the guard pin is with correct length and well centered. If You need guidance, ask. My advice is to use banking pins for reference when adjusting the pallets position. Just adjust pallets by leaving small 'run to the banking' on both sides and check what the drop lock will be. As the drop lock may differ on entry and exit pallet, especially if they are not 'pair', evaluation of the drop lock must be done on the pallet where the drop lock is smaller. Usually the result that this way of adjustment gives is good and no additional corrections are needed, but this will get clear in the process. Clean the shellac from the slots of the fork. Adjustment is easy when the pallets fit in the slots tight and stay there firm enough for the movement to be able to work for awhile with no need of shellacking. Use brass tweezers to put the pallets in slots and correct their position

[caseback]

I have fitted new jewels and adjusted them so the lock depth is about 1/3 of their width. I had to shorten the new entry jewel. For this I hand-drilled a small hole in a piece of pegwood and ground it on a diamondplate. Worked like a charm. Can't wait to see if it will all actually work..