On Fri, 14 Jun 2002, Tony Moss wrote: > Dave Bell wrote: > > >One important consideration here is to make the pinhole in as thin as > >possible a sheet of material. Foil stretched over a hoop would work well, > >and be easy to punch. Pinhole camera buffs make a point (heh!) of drilling > >a hole, using a sharp needle, with a backup block of plastic or the like, > >to ensure a smooth, burr-free hole. Then polish both sides with very fine > >emory cloth. For these shadow sharpeners, I doubt that's all necessary, > >but a "flat" hole in thin stock would be best for you, too... > > Perhaps the only way to get a truly 'burr-free' and 'surrounding > depression free' hole is to chemically etch it. > > (Trust him to think of a difficult solution!!!) ;-) > > Tony Moss
Tony, I'd rather say "elegant"! And any over-etch would only serve to thin the edge, better approaching the ideal zero thickness hole... Thin brass stock is available at the nearest craft store (for embossing paper), and wouldn't ferric chloride from the electronics shop do for etchant? Ideally, you would probably want photo resist, which should still be available the same place, but how about paint, sprayed over press-apply dots? Apply the dot diameter for the hole, paint both sides of the brass, then pick off the dot with a needle and etch. Should work! Dave 37.29N 121.97W -
