Which slotting screw head file for balance screws ?

[mikepilk]

Having fitted a new balance staff to an Omega 26.5T3, I found that the balance is a lot out of poise. 

I have a couple of tools which make countersink holes in to screw heads - but they look untidy and don't want to do that. 

So I've decided to buy a slotting screw head file, but don't know which one. Cousin's have them listed as 'Cut 2' to 'Cut 8' (the finest),

https://www.cousinsuk.com/product/slotting-screw-head-1850-vallorbe-swiss

Could someone please suggest the most appropriate file ?

 

[nickelsilver]

Definitely the finest, but I don't think currently available ones are really fine enough. Unless you're dealing with a truly valuable and rare piece it's really ok to take some material from the center of the head.

[praezis]

When slotted balances are out of poise, you should also consider bent balance halves. Your slots look as if they are of different width.

Frank

[mikepilk]

30 minutes ago, praezis said:

When slotted balances are out of poise, you should also consider bent balance halves. Your slots look as if they are of different width.

Frank

I hadn't spotted that. It's heavy opposite the impulse jewel, and the slot does look a bit wider on that side.

I managed to find sizes of slotting files on the Vallorbe website. The finest listed is "cut 8",  = 0.35 mm, much too big for these screws.

Some of the screws have already been cut. I might be able to swap some round to get closet to balance.