On Sunday, May 24, 2015 at 1:23:26 AM UTC-4, Cydrome Leader wrote:

How did they manufacture it in the first place?

I've wondered the same about the orifice in propane torches. They're made
of brass and the holes is barely visible. A #80 drill bit is much much
larger than those holes.

I do not know, but one way would be to put a aluminum wire inside a brass tube. Then draw the brass tube down in size, machine the brass to the right dimensions and then etch out the aluminum.

They make 10 ma fuses in a similar way. Except for the fuses they put an platinum wire inside a copper tube. And etch the copper off the platinum.
A 10 ma fuse is so thin, you can barely see it with a magnifying glass.

Dan