"Tim Wescott" wrote in message
...
I have seen (held in my hands, actually), metal parts that are made by
etching thin steel with acid (presumably after printing on a resist).
It's great stuff for making optical stops, encoder wheels, and other
things where the worst that the metal has to resist is a stream of
photons smacking into it.

The steel in question appears to be either stainless steel or tin plate,
dead soft, and is maybe 5 or 10 mils thick.

What's the processing called in the industry? What sort of shop should I
direct someone to look for in their yellow pages or their Thomas
Register? What sort accuracies can one expect, and setup costs, and
fabrication costs?

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

Hi Tim,

The usual process is as you described and called variously photo etching,
photo-chemical machining, photo-chemical milling, chemical machining. There
are a bunch of places that do this if you search with those terms.
Tolerances depend on the metal thickness and can be as small as a couple of
microns. The price per square inch is pretty low, but the tooling charges
can be several thousand. The usual materials are stainless and berylium
copper, but they can do others as well.

There is another company called Metrigraphics
(http://www.metrigraphicsllc.com/) that does electroforming
(electrochemical deposition on a mandrel). They get very nice edge surface
finish and edge roughness and can do very small apertures repeatably. I
think the tooling and per part cost is more though.

If you are looking just for small pinholes or slits, National Aperture has
them off the shelf (http://www.nationalaperture.com/)