Re: gEDA-user: DIY brass stencils

[John Griessen <john@xxxxxxxxxxxxxx>]

DJ Delorie wrote:
> The issue is that, if you're etching through 5 mil of brass, you
> should expect 5 mil of undercutting.  I don't think there's much of a
> way around that, so I'm kinda limited to a 5 mil radius by the time
> I'm through the panel. 

What about the methods of electro-polishing?  I think that may apply in some 
commercial secret formulas to get a better etch wall...  A lot of those kinds of 
ideas get discussed on the MEMS list, but often with non metal -- more SiO2 
etching.  In electro-polishing, the etchant has gelling properties adjusted so 
the effective concentration in a low area or corner is less than on a high spot 
or straight long edge.  At first everything etches at the same rate, but then 
the etchant trapped in corners and at the bottom of the undercut gets depleted.

That kind of formula might give better corners while still giving a slanted edge 
like the first experiment with the wiping technique.  (Just idea generating -- 
not tried by me yet)

Spray etching or good stirring with a slight amount of gel added might be good...

John G


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user