----- Original Message -----
From: "ROGER ARMOUR" <ro...@rharmour.fsnet.co.uk>
> Thank you Guillermo and Bill for your comments. How do you make pinholes
as
> small as 0.035 mm Guillermo?
> Thanks
Roger,
If you really mean 0.035mm, I can not make them that small,
couldn't use them if I could make them, actually. The "optimum" focal length
for such small pinhole would be around 0.9mm!
The smallest pinhole I have made is 0.004" or 0.1mm. Independently of the
size, my technique uses brass 0.002" thick for pinholes above 0.0065"
pinholes and brass 0.001" thick for under 0.0065" ones. For very small
holes, I use sharpened needles (sharpening done using 600 grit black sand
paper), rest the center of the brass on my left index finger and the needle
on point I want the pinhole to be, applying some pressure and
rotating/drilling action at the same time until I start feeling the tip of
the needle on my left index finger. I then sand the brass using 600 grip
sandpaper, apply some canned air and check the pinhole with a measuring
microscope. Invariable, the pinhole would have lots of burrs and not the
required size. I sharpen the needle again and keep working on the hole in
the same way as described until I get what I am looking for, the only
difference is that sandpaper is used only the first time and a pencil eraser
for the rest.
Guillermo
