Jump to content

D'oh, fitted wrong balance hole jewel. Is there anywhere to look up balance staff pivot sizes ?


Recommended Posts

Having swapped the lower balance hole jewel on a Movado 150MN, I realise the hole is too small 😟

Not having a pivot gauge, I use a micrometer - I know it's dangerous! . So rather than close the jaws on the pivot, I set say 0.09mm, and gently lower the pivot to see if it fits.

I must have made a mistake, as I've re-measured at about 0.095mm*. Which seems an odd number.  Do I need a 0.10 mm or 0.11 mm hole?

There's plenty of sites showing balance staff sizes, but I haven't found any listing pivot size. Anyone know how I can determine it ?

* I wonder about the accuracy of my micrometer as the 0.09 mm hole jewels I bought will slide over the pivot, though they are a snug fit

image.png.c9ad6939809f4e6fc7c3a39451eb1611.png

Edited by mikepilk
Link to comment
Share on other sites

I don't know any source of info for pivot sizes, with the exception of some old info on American stuff. If the jewel fits, but doesn't want to tilt at all*, I would go to a 0.10mm hole. Manufacturers did indeed use half and even quarter sizes (0.095mm for example) for jewels, but in a case like this going up to 0.10mm with a 0.09mm fitting "snug" should be just right.

 

*With a proper balance jewel, the hole will be olive shape, and even if very close in size should allow a surprising amount of tilt.

  • Thanks 1
Link to comment
Share on other sites

3 hours ago, mikepilk said:

Having swapped the lower balance hole jewel on a Movado 150MN, I realise the hole is too small 😟

Not having a pivot gauge, I use a micrometer - I know it's dangerous! . So rather than close the jaws on the pivot, I set say 0.09mm, and gently lower the pivot to see if it fits.

I must have made a mistake, as I've re-measured at about 0.095mm*. Which seems an odd number.  Do I need a 0.10 mm or 0.11 mm hole?

There's plenty of sites showing balance staff sizes, but I haven't found any listing pivot size. Anyone know how I can determine it ?

* I wonder about the accuracy of my micrometer as the 0.09 mm hole jewels I bought will slide over the pivot, though they are a snug fit

image.png.c9ad6939809f4e6fc7c3a39451eb1611.png

Jacot time ? Is the reason pivot sizes aren't listed because they are easily adjusted ?

Link to comment
Share on other sites

4 minutes ago, Neverenoughwatches said:

Jacot time ? Is the reason pivot sizes aren't listed because they are easily adjusted ?

I don't want to mess with the pivots - I just fitted a new balance staff ! 

I just messed up measuring the pivot sizes when I ordered the hole jewel. 
I've broken pivots before when measuring with a micrometer, so I was very cautious, and obviously got it wrong.
What I should have done: I have some spare 0.09mm Incabloc hole jewels. I could have sat one on the pivot to see how it fit.

It is odd though, that all the dimensions of balance staffs are shown apart from the pivot size.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



×
×
  • Create New...