milling pc boards (was: hobbyists strike again)

[Wow, it seems I struck a nerve with this pc board question. Although the
consensus seems to be that etching is the way to go, people who have cnc
milling machines and need pc boards persist in trying to figure out a way
to make this work. I wonder if anybody's had any luck with it, or if it's
like looking for the Northwest Passage...]

Dan Mauch" <dmauch@...> wrote:
Subject: Re: Hobbyists strike again

The problem is that the
artwork looks really good but when I try the trace programs the straight
line traces become a bit ragged and the pads are not perfectly round.
I really did not want to buy Z trace for $300 to convert the Gerber files
to Gocode.

[Could you tell us a little more about Z trace? Do you think it would
really solve this problem? Does it only deal with Gerber files, or can it
read hpgls and dxfs too?]

So I am still looking for a cheap easy way to mill the outlines of the
traces.I too have a professional exposure unit and can etch a board really
quickly
but you have to deal with all those chemicals. I think that milling them
would be somewhat cheaper.

Dan Falck <dfalck@...> wrote:

A couple of years ago, I milled the PCBs for my stepper driver system. At
the time, I was using Danplot/Dancad and Autocad.

[How did you like the Danplot/Dancad combo? What would you use if you
wanted to do this now? What about the DeskNC stuff?]

I used Autocad to draw
the circuit traces and holes on seperate layers, then sent out a HPGL file
to Dancad for converting to Danplot. I used double stick carpet tape to
hold the boards down to milled flat stock that was held in the vise.

[How did that work? Were you just removing copper, or was there some
fiberglass being removed as well?]

My
cutters were carbide v bits that I ground by hand.

[You actually fabricated these cutters from scratch, or do you mean that
you kept grinding them down as they wore out, sort of like sharpening a
pencil?]

You can look at some
pictures of that setup at : www.metalworking.com under "dfmill.jpg" in
the older file directories. The prerequisite for all of this would be a
cnc mill, which I had ( I was using smaller drives at the time and wanted
to build more powerful ones). It takes time to outline the traces in
Autocad, but I'm sure that one could use Protel Easy Trax or something
similar to do it faster.

[I'm not familiar with this one- could you tell us about it?]

I am fluent in Acad, so that's why I did it.
You can also get a free copy of Intellicad at www.cadopia.com (I think
that's right). It is 11 megs, but works just like Autocad 13 and is free.

Dan Falck

[Thanks for the tip!]


Jon Elson <jmelson@...> wrote

If you never want to make two of a particular PCB, milling it may not be
so horrible, but it eats expensive carbide cutters for lunch. A typical
6" square board, double sided will just about use up a $20 milling tool.

[Since you're just using the last few thousandths of the cutter, can't you
grind down the ends as you use them up? It sounds like these must be eating
some glass, since copper wouldn't be a problem for the carbide.]

This was confided to me by someone who sold the LPKF machine.

[Is this a special purpose circuit board machine?]

That didn't sound good! Plus, you have to flip the board over and
maintain registration for the 2nd side.

[Perhaps a jig would help?]

Andrew

Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com