ATM Making a Pinhole

[Anthony Stillman <atmer@flash.net>]

I not sure where I learned this.  I do know I've been making pinholes this
way for roughly the last thirty years.

In thin metal stock, I generally use brass shim, against a hard surface,
use a pin point to press a small dimple into the metal (not through).  Use
very fine sandpaper (600-1500) against a flat surface to sand off the
dimple.  The size of the dimple and how much sanding will determine the
size of the  hole.  Using this technique, I've been able to make quite
small holes with relatively clean edges (10 um in Ti foil).  On occasion I
tried to gently burnish the edge of a larger hole with the tip of the pin.
I've had limited success with this.

Anthony