Replacement Balance jewel hole for pocket watch.

[jnachman]

Hi there, i have replaced a upper cracked balance jewel with another from a matching movement.

When i place the bridge over the balance wheel it starts to spin. However on tightening the screw, its stops and isnt free.

Could it be that the jewel has been pushied in too much, i wouldnt of thought so as the cap is a screw type?

Balance Pivots look good.

Its a grade 109 Elgin Size 10 Pocket watch?

Thanks

Jonathan

[c.kelly]

Hi,
I have been thinking about this for a day or so and have a thought. Is it possible that your balance cock is not sitting level or has been bent at some time? Had similar issue happen to me and found some tiny scratch marks on plate where someone had raised up the metal to accomodate a bent balance cock. When I asked here Bob also said that sometimes people have been known to shim up balance cock as well with thin piece of metal such as tin foil. What I might try is to put jewel back on donor movement then attach your good balance to that balance cock and see if that will run in your movement. As I write this I have forgotten which jewel you replaced but am assuming it was one on balance cock. Before replacing balance check plate underneath where it sits for small scratch marks and raised pieces of metel. If any are found they will have to be removed or you could transfer parts over and use plate off donor movement as well. As you can tell I have assumed a lot of things here. I have assumed balance staff pivots aren’t bent and they are seated properly in jewels. Those things could also give same issue. Just wanted to give you something to try as a trouble shooting method.
Other possible issues could be bent hairspring that comes in contact as balance is tightened.
Charles

[jnachman]

Hi there, i have come to the same conclusions – just waiting on when i can get some time to test – i think the scratches were known as pig ears.

Thanks – ill let you know how i get on.

Jonathan

[digitaltripper]

@jnachman wrote:

Hi there, i have replaced a upper cracked balance jewel with another from a matching movement.

When i place the bridge over the balance wheel it starts to spin. However on tightening the screw, its stops and isnt free.

Could it be that the jewel has been pushied in too much, i wouldnt of thought so as the cap is a screw type?

Balance Pivots look good.

Its a grade 109 Elgin Size 10 Pocket watch?

Thanks

Jonathan

Hi Johnathan
I had a similar situation on my first Elgin 16s 15 jewel open face pocket watch. I had to restaff the watch. After restaffing and truing the balance wheel, setting it in without it’s hairspring, roller jewel, etc. it would spin until I tightened it down. The cause was the staff pivots were not passing thru the jewel holes.

My watch maker / instructor (Nolan Holdridge) used his lathe to cut the pivots down slightly to fit the jewels. Yes it was an Elgin 861 balance staff which is what that watch calls for but the jewel holes were smaller than the staff pivots. Is it possible that there may be slight variations in dimensions even from donor watches of the same type?

Jim

[Bob Tascione]

Hi Jim,

Yes it is possible. The 861 staff was produced and made available in three different pivot sizes 11, 12 and 13 and also old and new style. Jewel hole gauges are very handy and helpful when ordering a staff but if the broken staff has a good pivot on one side then measuring and giving that pivot size when ordering will “usually” insure receiving the correct staff.

Hope this helps Jim,
Bob

[david pierce]

Jim,
I just read this a few minutes ago. It looks to me like the conical portion of the balance staff is pushing up into the jewel. This is probably what cracked the jewel in the first place. As you tighten the plate, the cone of the staff is getting squeezed against the jewel face. Since the staff is easier to machine than the jewel, you will probably have to turn the cone back a few thousandths of and inch so it will fit. To gauge how far to cut the cone back, put some shim stock under the plate and tighten it down, If the balance will now turn when tightened with the shims, then the thickness of the shims will tell you how far to machine the cone back in order to make it work.
David Pierce

[digitaltripper]

Hi Bob, Hi David,

Thank you both for your responses!! Wow I had no idea that the staff’s came with different pivot sizes and the person who sold me the staff (thru feebay) did not mention it either. I am working toward getting tools to measure jewel holes as well as getting a lathe so that I can do my own work.

David I never considered that the shoulder may be the cause, I just let Nolan handle it. It could very well have been that.

Thanks again!!

Jim

[david pierce]

Jim,
There is a company called Vermont that makes pin gauges. They offer 55 piece sets from .006-.060 in .0002 under and .0002 over. This should cover the hole sizes for most watches and clocks except for small ladies watches. I have seen the pivots of these as small as .004 or @ 1/10 of a millimeter. These sets can be purchased from most industrial tool supply houses such as M S C. For the lathe take a look at the made in China lathe sold by numerous mail order suppliers such as Sincere. The lathes are excellent machines for small parts requiring light cuts. The basic lathe including a cross slide and a collet holding tailstock can be purchased for less than $600.00. Accessories such as an extra long bed, dividing attachments, milling attachment, graver tool rest, a sensative drill press conversion kit, collets and chucks are affordable and available
David

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