You would do better getting one with a tray.
Then you just fasten the board to the tray and you're off.
Much better precision.

    Kyrre


----- Original Message -----
From: "David Minkler" <Mink@LUXTRON.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, November 13, 2002 9:36 PM
Subject: Re: [EE]: Printer to PCB?


> HP 7475A plotters are 'nearly' free (plus shipping) on ebay.  Search on
> 7475a.
>
> Dave
>
> Dale Botkin wrote:
> >
> > On Wed, 13 Nov 2002, Olin Lathrop wrote:
> >
> > > Back in 1980 I was right out of school and working for HP.  I wanted a
way
> > > to make my own circuit boards for personal projects like you guys are
> > > talking about.
> >
> > 8< snip...
> >
> > I used to have an old IBM six-pen plotter (a re-labeled HP 7475, I
think,
> > B size flatbed).  I had excellent luck using a .5mm permanent marker
that
> > I found at an art store.  I had a cut-down HP felt tip plotter pen body
> > that the new marker friction-fit into.  By setting the plot speed down
to
> > 1 or 2 inches per second, I got near perfect boards every time.  I was
> > only making single sided boards, but I suppose with enough work one
could
> > probably get a double sided board done the same way.
> >
> > The plotter moved the pen in the X axis and the paper in the Y axis by
> > means of a rubber lower roller and a grit-faced upper roller.  I did
find
> > I had to tape the PCB to a sheet of paper because the registration
process
> > was at high speed regardless of the plot speed you had set, and the
> > rollers didn't grip the PCB material well enough to prevent slipping
under
> > that kind of acceleration.
> >
> > The pen was a common ultra-fine permanent ink pen, available in several
> > colors from the local art supply joint.  Its only remarkable feature was
> > that it was small enough in diameter to fit into an HP pen body that had
> > the top and bottom removed so the pen gripper mechanism could hold onto
> > it.  I used this setup numerous times with excellent results; the only
> > reason I didn't mention it long ago is that old HP plotters are kind fo
> > hard to come by any more.  I think I did mention this on the list a
couple
> > of years ago.
> >
> > Dale
> >
> > --
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>

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