Evening Martin,

Thanks for the input; some interesting points there.  I've only managed to
see a CNC etched PCB from the various online resources, so obviously the finer
points that you've mentioned from first-hand are worth noting.  Sounds like
not a great way to produce industrial prototypes after all, but still
good for hobbyists - the boards have *got* to look better than dead bug
prototypes !

Cheers,

Pete Restall

--- Original Message ---
I had access to a machine several years ago in college. I was never
able to get very good boards with it. Milling the PCB results in
grooves on the surface which makes a rough and unsightly board. There
is no solder mask or silkscreen. Unless the bit is brand new it will
do a poor job milling the copper, leaving burrs that will short out
traces. IIRC the minimum trace/space with this machine was 10mil/10mil
(0.01 inch) which precludes any modern parts. You can do two layer
boards but you can't do plated through vias or holes.

All-in-all it's a bum deal for a machine that is (at minimum) several
thousand dollars. It hasn't really caught on because people who have
the capital to pay for it are probably willing to pay to have boards
expedited, and are probably also doing "state-of-1970" circuit boards
that are too advanced for a milling machine to produce.

-- 
Martin K.
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