Homebrew PCBs

hi , i made a prg work with plt files, download at www.geocities.com\pancary

----- Original Message -----
From: Stefan Trethan <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, May 13, 2003 4:02 AM
Subject: Re: RE: [Homebrew_PCBs] HPGL output (was PCB design software)


> ah i see, i see.
>
> if you have this very handy function in eagle this makes the thing a lot
easier.
>
> i think this may also be there for making copper plains, determining
design rule violations, etc.
> this would simplify the overall thing.
> my thought was the whole time how the hell can i tell that 2 arcs,
different sizes are from one pad and
> not 2 differtent pads. also when calculating the coordinates this would
not be too easy to tell.
>
>
> which shape has the tip of your scretching tool?
>
> have you any results ready to meke a picture?
> i would be very interested in it.
>
> regards
> stefan
>
> 12.05.2003 22:25:44, Brian Schmalz <brian.s@...> wrote:
>
> >> nice to see there has one done the "scratch 'n etch" tool i
> >> asked a few days ago.
> >
> >Yes, it does work OK - and for me I only need OK, not great. Super
> >easy/cheap way to try out a board to get all the bugs out.
> >
> >> how do you detect when a line is on the outside of a
> >> trace/pad and when a line/arc is the outermost?
> >> so you can tell what actually is the outline?
> >
> >I had to use some really crazy tricks of the ULP (User Language Program)
in
> >Eagle. What the program does is use a command in Eagle that will draw
lines
> >around all of the existing traces. You pass this command a 'distance',
and
> >it computes the correct lines based upon that distance from the nets. So
my
> >ULP calls itself repeatedly (recursion) with increasing values of the
> >'distance'. So if I want at least 50mils of space around each net, and my
> >scratch tip is 5mil wide, the program will call itself 9 times, starting
> >with a distance of 2.5 mil, and advancing up to 47.5 mil for the
distance,
> >generating a whole series of lines each run. I just execute for 'x'
number
> >of times, and that gives the proper number of concentric lines.
> >
> >> i first thought of plotting the layer with the drill drawing
> >> on it to get the holes "punched".
> >> i'm really wondering how you can tell when a line is only a
> >> fill line and when it is a outline.
> >
> >To me there's no difference. I never 'plot' the real artwork in any way -
> >the ULP just goes through the Eagle database of nets and draws lines
around
> >each net. The nets are never drawn into the HGPL file, so there's never a
> >need to know the difference. I understand your question, I think, and if
I
> >was starting with just plain artwork (like what a printer would print
from
> >what's on the screen of a board file) then you're right, I'd have a big
> >problem.
> >
> >> how is the match on the edges of tracks? i know one in
> >> australia who has written a similar tool but for
> >
> >Ahh. Now there's the rub. ;-) The match is terrible because the
scratching
> >tip is drawn along by the plotter, and so is always 'following' the
desired
> >point of contact. So what I do is I draw each 'line' twice, without
lifting
> >the pen from the board between lines. (Each 'line' is actually a long
series
> >of lines that forms a closed polygon that totally rings each net.)
> >
> >*Brian
> >
> >
> >
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