HP plotters - test-drb@ccmp.vtda.org

3 Sep 1999

If you're determined to use a flatbed plotter to mill PCB's, you could
consider making a custom "quill" powered by a flexible-cable DREMEL tool.
You will need a really small (e.g. 0.020") carbide milling tool and LOTS of
them, since they break easily.  I'd advise a very modest feed rate and, of
course, since you can't place traces at any less than 0.030" centers, and
that's pretty agressive, you will have to limit yourself to a VERY coarse
routing grid.

I'm told that you can expose and etch your own PCB quite a bit quicker than
you can mill one, and, aside from the chemicals and the associated disposal
problems, build better boards with chemicals than with a milling approach,
I'd suggest you look for a good, positive resist material you can apply with
the plotter in a refillable pen.  There, your only problem will be in
adjusting the height of the pen and the speed of the plotter to allow for
the thickness of the PCB, and the thickness of the probably latex base
ink/resist.

Dick
-----Original Message-----
From: Joe &lt;rigdonj(a)intellistar.net&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Friday, September 03, 1999 8:57 AM
Subject: Re: HP plotters

...
 At 03:42 AM 9/3/99 -0000, you wrote:
>Joe wrote:
>>    I've heard that there are knifes available that can be used in them
to
...
 >> cut strip lines on copper PCB and knifes for
cutting out vinyl and other
>> materials but I don't know what they cost or where you can get them.
Does
...
    anyone know any more about them? 
There are small machines designed for the express purpose of milling
printed circuit boards.  There's no way a pen plotter will be able to do
that with a knife or drill; they weren't designed to produce enough force
or move enough mass for that type of work. 
   That's what I thought but I've seen people do it. One of the classes at
my unverisity used some kind of knife in a HP plotter to make strip lines
on a PCB for microwave work. Apparently they had been doing it for a while
and it worked successfully.  I wasn't interested in it at the time so I
didn't pay attention to what they were doing and I don't even know which
plotter they used except that it was a large flat bed HP plotter.

   Joe