Joe Gwinn wrote:


Chemical or electrochemical machining? Put down tape the size of what
is wanted, and etch the rest away. Phosphor bronze is not hard to
etch.
This will probably leave a ragged edge, as the etchant will get up
under the glue of the tape. But, maybe some hand finishing could
clean that up. I etch .003" brass shim stock all the time to make
solder stencils for electronic manufacturing. I use a laminated dry
film resist that is then exposed through a master photo film and
developed. This gives sharp edges and fine detail. But, I sometimes
mask off an area with tape just to prevent using up the etchant, and
this suffers from etchant getting under the edge of the tape.

Jon