Homebrew PCBs

On Mon, 2003-05-12 at 10:27, Stefan Trethan wrote:
> i have downloaded eagle.
> i only tried it some minutes but it seems less powerful than orcad
> which i use now.
> 
> the problem is it also doesn't keep the drill holes open for me.
> 
> you simply can edit the hpgl file to set the force, my plotter doesn't
> support setting the force so i 
> never tried this. hpgl commands are very easy (similar to cnc
> commands). there is much documentation on 
> the web.

  Yes, that's what I do currently.


> one method to get the drill holes open may be to find a converter tool
> which converts some printer 
> format (pcl, ps, maybe pdf) or a plain image to a hpgl (1) file. this
> should be one which sets the outer 
> lines to fill the dark areas exactly and fills in between. i have
> searched such a tool quite a while, 
> all results i got were very, very poor, if i got a output file at all.

  I tried just that, using a package called "pstoedit", which will
convert postscript (and other vector formats) to a wide range of output
formats, including HPGL.  The problem is, postscript is a _lot_ smarter
than hpgl.  For example, I wanted to be able to try the "scratch and
etch" method for making a PCB, so I needed a negative of the output. 
Eagle has an "inverted PS" option for output, which I used as an input
to pstoedit for producing HPGL.  The problem is, the way it does this is
to print a black rectangle and then draw the traces in white.  The HPGL
output attempted to reproduce this by printing a filled rectangle and
then drawing the traces in another color on top of it.  Didn't work too
well obviously.  Similarly, the only way to handle pads with unfilled
drill holes would be to draw X number of concentric circles (each a pen
diameter smaller) until the resulting unfilled area was the correct
size.  HPGL does have a filled circle command as far as I know, but you
can't subtract out polygons/arcs from the fill.

> 
> if anyone knows a converter please write.
> 
> the advantage of a converter is that i do get printer files (b/w)
> which have the holes open but i don't 
> get plotter files.
> 
> thanks for the tip with eagle.
> 

  Incidentally, it is possible to print PS output with non-filled drill
holes.  I just made a PCB that way the other day.  It's a matter of
fooling around with which layers get plotted in the CAM processor, and I
can't remember which layers need to be turned off.

Larry