Balance Bridge Jewel Hole Dilemma.

[Len33]

I recently replaced a balance staff in a pocket watch and, once assembled, the balance wheel was too tight because the pinion gripped the top jewel. Removing the bridge brought the complete wheel assembly with it and it was quite a job to separate the two without breaking anything.

There's an answer to every (horological) question and I just know it will be found on this site.

Over to you!

[Geo]

You could either strip the balance and polish the offending pinion down to size using a Jacot tool, or replace the jewel with one that better fits the pinion.

[Mark]

You could either strip the balance and polish the offending pinion down to size using a Jacot tool, or replace the jewel with one that better fits the pinion.

 

I recommend the first option :)

[clockboy]

Another dodge that sometimes works is packing under the balance bridge.

[Mark]

Another dodge that sometimes works is packing under the balance bridge.

 

 

As a co-incidence I was working on a lovely Waltham today, took the balance off and found a nice bit of card under the cock. Hairs included!

 

To be honest, not the best solution. 

 

To resolve this it took me two minutes to carefully reduce the top and bottom pivot lengths so there was enough end shake.

 

 

 

[clockboy]

A black hair so it was certainly not an old duffer like me.

However I now own a jacot so when confronted with this scenario I will follow suite.

[Len33]

Well I'm blowed! I would never have thought of using 'shims' to raise the bridge height.

And, as for the hair..........yuk!

I have no Jacot tool so, to be absolutely honest, I am thinking of taking a piece off the tin foil roll and using that.

It either works, or it doesn't.

As another thought, though, how would I reduce the pivot length without snapping it off?

[bobm12]

Nice solution Mark, not that I expected less from a pro.

 

Cheers,

 

Bob

[Geo]

I'm just back from the pub, so I hope I get this right!

If the pinion is too tight in the jewel, and this is evident because when you lifted the cock the balance came with it, the problem is not end shake but too large pinion diameter. Placing a shim under the cock is not going to sort the problem. You will have to reduce the diameter of the pinion or fit a jewel with a larger internal diameter.

[Len33]

Yes, I see the logic of your comment and it represents a fair case.

I was thinking of inserting the stud into a Dremel tool chuck and, via a separate speed controller, (Electric ''tap') reducing the diameter with flour grade wet and dry.

However, as the Dremel chuck does not meet close enough to hold the staff, that idea has been abandoned.

I will get there in the end, but it looks like it's going to be a slow journey!

[ricardopalamino]

Hi all , Mark , didn't  i see on one of your videos where you used a broach type of device to enlarge a jewel hole ?  Or is that the Jacot tool that Geo took to the Pub with him ? ~~~~~~~~just kidding Geo  :mp3:    If it is that tool I am not familiar with it .

[clockboy]

I expect Mark used his Seize jeweling tool & the cutting is done with one of the reamers. The reamers are specific sizes for exact friction fitting of jewels.

 

 

 

[ricardopalamino]

Thanks Clockboy ,..so the reamer is used to size a hole for the outside diameter of the jewel and not to ream the pivot hole of the jewel...is that correct ?

[Geo]

That's correct Louis.

[clockwatcher]

I think Len33 was kidding when he said about using tinfoil for a shim - at least I hope he was! Whether or not it would have fixed the pinion problem, I believe it would have caused a galvanic corrosion problem between the steel and aluminium. It would probably need a bit of liquid as well but I doubt that a pocket watch would be immune from a little atmospheric moisture.

[anilv]

You can find shims made of copper(ish) foil on some Russian watches.

Anil

[Mark]

Hi all , Mark , didn't  i see on one of your videos where you used a broach type of device to enlarge a jewel hole ?  Or is that the Jacot tool that Geo took to the Pub with him ? ~~~~~~~~just kidding Geo  :mp3:    If it is that tool I am not familiar with it .

 

The jeweling tool is used to press-fit friction jewels. If the hole in a plate is not large enough for a particular jewel then you can also use the tool to ream out the hole in order for the jewel to be fitted.

 

The Jacot tool is used to polish pivots, and can also be used to reduce the pivot thickness and length.

 

Jewelling Tool:

 

 

Jacot tool:

 

[bobm12]

Hi Mark, I have a question that has been in the back of my head for sometime. I own a K&D 18R staking tool with the jeweling attachment/handle+micrometer. Is there anything a true/dedicated jeweling tool can do that this K&K can not do? The reason of this question is that perhaps I may be needing a jeweling tool in the future. Please, advise!

 

Thank you in advance,

 

Cheers,

 

Bob

[ricardopalamino]

Very interesting ,  Thanks Guys.....

[Mark]

Hi Mark, I have a question that has been in the back of my head for sometime. I own a K&D 18R staking tool with the jeweling attachment/handle+micrometer. Is there anything a true/dedicated jeweling tool can do that this K&K can not do? The reason of this question is that perhaps I may be needing a jeweling tool in the future. Please, advise!

 

Thank you in advance,

 

Cheers,

 

Bob

 

 

I don't think buying a dedicated set will give you any advantages Bob as far as I know. However, I have never used a K&D set but if it has the handle and micrometer plus a good set of reamers you should be fine with that.

[bobm12]

Thank you Mark, much appreciated! This is the confirmation I was hoping for, now my wallet can rest at peace! :)

[Len33]

I'm going to ask a question which, had the answer been in the affirmative would, I feel, have already been suggested.

Is it possible to use a drill to enlarge the jewel hole sufficiently?

If so, do you think that the pressure on an Archemedes drill would provide too much strain on the jewel?

Or, would a motorised chuck (Used with great care) achieve the desired results?

[bobm12]

Hi Len,

 

I would assume that after the hole is opened at the factory, it takes the jeweling tool or similar to make sure that whatever modification on the existing hole is true to center and size. By drilling on an existing drilled hole you are risking undesirable side effects to the plate in question. Again, just a beginner's opinion but I hope some other, more experienced, members can add to that and or correct me if I'm wrong.

 

Cheers,

 

Bob

[Geo]

I'm going to ask a question which, had the answer been in the affirmative would, I feel, have already been suggested.

Is it possible to use a drill to enlarge the jewel hole sufficiently?

If so, do you think that the pressure on an Archemedes drill would provide too much strain on the jewel?

Or, would a motorised chuck (Used with great care) achieve the desired results?

Len I hate to be negative, but the answer to each of your three questions is no. :(

1) You could undoubtably enlarge the hole in the plate with a drill, but it would probably end up off Icentre and not have the required size or concentricity required.

2) This sounds like you want to enlarge the hole in the jewel itself and that would be a non starter.

3) If you were to use a motorised device, you would only end up destroying the watch quicker.

[Mark]

I agree with Geo. Enlarging the hole in a jewel rather than reducing the pivot diameter is like filling a water with kettle.

 

It can be done but not with a drill. I have met somebody who makes jewels and he described to me how he does it although I have not watched him - it involves a watchmakers lathe, some fine string, diamond paste and a lot of time and patience as far as I remember. I can't remember how he drills the initial hole but I would guess diamonds are involved.