Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Codesuidae <codesuidae@...> wrote:
>
> Alan Marconett wrote:
> 
> > I like the idea of MILLING isolation traces for a board.
> 
> I've considered that as well (on my CNC Taig), but haven't
> gotten around to trying anything other than using it to drill
> the holes.  Having done a number of boards with chemical
> etching and knowing how simple it is, I haven't gotten up
> the initiative to try milling one yet.
> 
> If you explore the option, would you mind posting details here?

Dave:

Ever since I turned my garage into a toxic soup when my
aquarium tank heater over heated my Ferric Cloride, I have
been interested in mechanical etching the trace outlines.
(Of course, my wife being really really annoyed had nothing
to do with it ;-)

The URL below show the floating Z-head I developed for
mechanical etching:

  <http://gramlich.net/projects/mill_lathe/index.html#The_Floating_Z_Head>

The mechanical etching bits come from Think and Tinker:

  <http://www.thinktink.com/stack/volumes/voli/store/mechmill.htm>

The concept here is that it can be challenging to get
your blank PCB flat with mill table over the entire
surface of your project.  The floating Z head allows
the Z cutter to "float" on top of the board and always
cuts exactly the same depth.  The design consists of
a Sherline header block hooked together with two
flexible sheets of metal to a Dremel(tm) motor tool
holder.  I'm using a Dremel for the cutter spindle to
get the highest RPM possible.

The drawbacks of mechanical etching is that the bits are
expensive ($6-10 each) and wear out after approximately
500-1000 linear inches of mechanical etching.  As usual,
there are no plated through holes, but that is fairly
typical of the Home Brew PCB crowd.

I had limited success with the setup shown until I
decided I needed to totally update my CNC setup.
The CNC update is well under way, but is still not
complete.

I hope this helps,

-Wayne