Biotar Set Screw broken, need new, or way to recut slot

[eggboy]

I picked up a glorious non-functioning prewar HEAVY Exakta mount Zeiss 5.8cm/2 Biotar. Good glass, good cosmetics, but heavy fogged glass, and some diaphragm and grease problems.

This thing is built to a much higher level than any other lens I've rebuilt, and I've rebuilt a lot of pre and post war German glass: Xenons, Tessars, Primoplans etc.

So far, I've re-riveted and broken diaphram blade, degreased/cleaned everything, fixing a lot of previous 'repairs'.

But, there are 2 set screws with one side of their heads broken.

I need to either find replacements, or, using some kind of micro saw, re-slot the heads.

I've no idea where to get micro set screws, or even a tiny little saw or file to reslot the screws. Any ideas?

Eugene

[Attila]

https://www.micro-tools.com/store/home.aspx

Try to ask them!

[eggboy]

Just for the heck of it, some pics of the pieces.

It has the craziest iris I've seen. Only 8 blades, but it's a dome. It actually curves up into the front element of the rearmost group. Crazy!


All the pieces:


The set screw in question is circled. The helical is actually bronze!!!


Disassembled blades:


More bits:


More bits: