milling pc boards

> From: "Dan Mauch" <dmauch@...>
>
> Since I have several CNC machines including a dyna 2400 mill I would prefer
> to mill the traces. The dyna is perfect for that kind of work.
> Dan

Do consider thought that you will be trading etchant disposal hassles
for airborne fiberglass dust concerns if you go the trace milling
route. Perhaps you can use plastic board material, or build a good
dust collector.

Chris

--
Christopher C. Stratton, stratton@...

[Good point- I'm not very fond of fiberglass dust. Where does one get blank
plastic boards, and do they work as well as fiberglass ones? Do they sag
when they get warm? They would probably be easier on the tooling.]

From: bfp@...:

>I looked at his PCB . What impressed me is that he is milling his traces.
>Dan
>
>[Even if he isn't, people keep asking me how they can do this. Is there a
>program out there (or a combination of programs, even) that simplifies this
>process so someone can go from a picture of a pc board to a g-code plot
>file? It would be nice if the hole-drilling were automated as well- am I
>dreaming? Does anybody out there cut pc boards with a mill, or is everybody
>convinced that etching is the way to go?]

I have been working on this same idea the program I have been
using is the EAGLE Layout Editor from CadSoft [http://www.cadsoftusa.com/%5d

[Welcome aboard, bfp. Thanks for pointing out the Eagle. This does look
like an excellent program for designing circuit boards- but is it as hard
to learn as it looks? And what do they mean by "copper pouring"? ]

it has a schematic editor,board layout,autorouter and toolpath output
there are both Linux & windows versions available so you can run it on an EMC
box for on the spot edits. It can be downloaded and run as a
non-comercial/freeware/demo for hobby users ,the board size is limited to
about 3.5"x4.2" and 2 signal layers - plenty big enough for a
modular machine control unit (one of my current projects)
once installed you can edit the device definitions file - eagle.def
to output any flavor of RS-274D that you want ,or use HPGL if youve got a
plotter.
Also on their download page under user files are several scripts that will
generate
a trace isolation toolpath for milling or engraving your board look for
mill2.ulp ,mill_drill.ulp ,etc.The board layout editor can also be used for
simple 2d cad with G-code output,using a difrent layer for each tool.
the way I have been making small PCBs is to chuck a Sharpie(R) marker
in a locked spindle (or plotter) and draw the traces directly onto the copper
then etch as usual ,the ultra fine point pens have a line width of about
.7mm and the thicker markers can be blunted to about 1/8" width for power
traces
just be sure to draw slowly enough to leave a good thick resist layer or
the lines will etch thru (my first plotted board had all the pads but no
traces.connect the dots anyone?) a set of good technical drafting or
plotter pens should go down to .25mm wide if you dont mind the price ("light"
crashes jump from 50cents to 8$ ,"heavy" ones stay about the same)
to hold the board down I use a some strips of thin double stick tape on a
sacrificial backing board.

[Does the mill_drill utility track the traces, or the space between the
traces? For doing what you're talking about, the former would be fine, but
to mill the board with a cutter, the latter would be necessary. Is this
method supported?]

I wonder if you could draw the traces onto a non-conductive surface with one
of those conductive ink pens,then use an elecroless tin dip plating solution
to build them up to a good thickness? Has anyone tried this?


[I'd heard about the Sharpies for acid resist, but what pens are
conductive? The chemicals needed for building up copper with electricity
aren't as nasty as the ones that dissolve it, so even if the dip method
didn't work this might be viable if one invested in a small electroforming
setup, like the ones sold by Dalmar. These can also be used in reverse for
electro-etching, which might make the conventional appoach less toxic.]

Andrew Werby


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