Jewel replace size question

[JohnTosto 1]

Hi All

I have a pocket watch that I am working on that I needed to replace balance shaft and the upper and lower balance jewels.  Shaft has been replaced and both jewels are held in by jewel cap and screws so should be an easy replacement.

I found replacement jewels on ebay they are the right type (fits in balance cock) but the wrong pivot size, I ordered hole 13 thinking they would be pivot size .13 however they are pivot size .11 (used a jewel gauge to check). When ordering jewels was I wrong to think hole 13 was pivot .13?

Regards,

John

 

[JohnR725 867]

Out of curiosity make and model of the watch you're working on?

29 minutes ago, JohnTosto said:

I found replacement jewels on ebay they are the right type (fits in balance cock) but the wrong pivot size, I ordered hole 13 thinking they would be pivot size .13 however they are pivot size .11 (used a jewel gauge to check). When ordering jewels was I wrong to think hole 13 was pivot .13?

Okay I think you have two separate questions here? First if you have a hole  with the same diameter as a pivot you have zero clearance. So one has to either be bigger or smaller than the other so that they fit. Then a .13 mm hole should be that.  Then if you are ordering parts off of eBay and their loose or not in a package and especially if this pocket watches old then they could be just about anything.

[watchweasol 939]

Hi when ordering jewels  there are to things to consider 1. the hole into which the jewel fits 2 the hole into which the pivot fits and as JohnR explained if the pivot is .13 and you order a .13 Its not going to have any movement at all and will bind, there has to be clearance for movement and oil film.  Mark our Administrator has videos on the subject on Utube and are well worth watching.       cheers

[JohnTosto 1]

Hi All

Thanks I believe I understand, jewel hole 13 size does not mean you would pair with a .13 pivot shaft with a jewel that has a 13 hole it means that the jewel hole is .13 too.

Which now makes sense with what I was seeing when using the jewel gauges. I won't/shouldn't expected for a .13 gauge to fit in the jewel 13 hole as it would be a perfect fit and is why a .11 pivot gauge did fit as there is clearance.

So would I be correct in thinking if I have a balance shaft with a pivot size of .13 that the jewel I would want would be a 15 hole?

 

JohnR725, they are Elgin 291, I purchased 5 of them over last couple months(military black dial yr 1943). One I have working (you helped me my balance shaft question)  but wanted to replace the upper and lower jewels (balance shaft pivot .13) and why the question and based on both answers looks like I order wrong size.

Two others that I am taking advantage of current situation (staying home) to work on, both had broken balance shaft as well (both pivots) and I used the jewel gauges to figure what pivot size they mostly likely were by seeing which gauge fits into the jewel.

I haven't really looked at other two yet.

watchweasol thanks I will look for video (I have finished 1st two of his class videos working on 3rd).

 

Regards,

 

John

 

 

 

 

 

 

[JohnR725 867]

So is looking through my literature to see if anyone would give us a number I did get amusing chart that I'm going to Attach.

Then the other thing I have is the other method. That is placed the balance staff in the balance jewel assembly and note the lien? This will tell you if you have the right size staff. Of course it assumes that the jewels didn't get broken at the same time as the staff.