Internet Horology Club 185
Waltham Pivot Sizes

This topic can be found at:
https://ihc185.infopop.cc/eve/forums/a/tpc/f/3426047761/m/5581002303

February 15, 2008, 20:08
Dick Gilbert
Waltham Pivot Sizes
Hi Everyone,

First, I'd better introduce myself as a newbie! I live in Brisbane, Australia and I've been a watch fanatic for a short five years or so. My main areas of interest are American PW's and English Verge watches.

My problem lies in the selection of pivots when replacing broken balance staffs on American PW's. Up intil now I've been lucky and the selected pivot size seems to have been the correct variant. However, a recent replacement drops too far into the balance jewels resulting in massive end and side shake. The obvious inference (the jewels all appear to be fine) is that I need to go to the next pivot size up.

My question is then, "How should I determine the correct pivot size?" Measuring the remaining pivot seems a little 'chancey' and would be impossible if both pivots had been damaged.

I suppose the only real answer is to measure the jewel holes but I don't have the requisite pivot gauge to do this! Does anyone have an idea for accurately determining pivot size and, whilst we're on the subject, why were pivot sizes varied in the first place?

It occurs to me that pivots may have been 'beefed-up' if the original was found to be a bit weak in service. However, if this was the case wouldn't there be a record of the serial number from which the variation was made?

This is a great forum by the way, it amazes me how it took five years to find it!

All the best,

Dick
February 15, 2008, 20:13
Dick Gilbert
A quick update on my previous post, end shake is OK, it's just side shake that's the problem.

Dick
February 16, 2008, 19:50
Frank Juchniewicz
I would think that the pivot is too small for the balance jewel.
On ebay the jewel gauges do come up at times,I would watch for them, as they are very useful.

Frank
February 21, 2008, 02:45
Dick Gilbert
Thanks for that Frank, a pivot guage would seem to be the way to go. I'll keep an eye on eBay!

Thanks again,

Dick