Re: [CAD_CAM_EDM_DRO] Help: PCB Trace Milling Software

----- Original Message -----
From: Jon Elson <jmelson@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Monday, October 16, 2000 9:22 AM
Subject: Re: [CAD_CAM_EDM_DRO] Help: PCB Trace Milling Software


>
>
> Alan Marconett KM6VV wrote:
>
> > So how do we get from Gerber files to CNC files? As you observe, the
> > Gerber "plots" each trace, what we want is contours AROUND the traces!
> >
> > I examined an HPGL PCB plot file (see View Companion), and studied how
> >
> > multiple pen lines were combined to draw a trace.
>
> I figured out a VERY crude algorithm to do this, if anyone wants to try
> it.
> First, you map the extent of the drawing onto a bitmap. You then draw
> in the
> traces and pads, with the actual width or dimensions of the object. For
> instance,
> if the grid is 1 mil, then a 50 mil trace would be drawn by filling in a
> 50 bits wide
> track from start to finish.
>
> After this is all done, both traces and pads, you could raster through
> the thing,
> identifying all points where you cross from one 'color' to another. You
> have to do
> this in both axes to make sure you completely surround the traces and
> pads.
> This should define a 'border' as a closed pattern of border bits.
>
> A second pass could define all separated borders by starting randomly at
> the
> first border seen and following all the way around its edge until you
> get back to
> the starting point, and numbering all these bits as part of border # 1.
> You then scan for the next unmarked border, and follow it, marking it
> #2.
> You repeat this until there are no unmarked border bits left in the map.
>
> You can now check each border to see which side it encloses from some
> starting
> point, and create offset tool paths to cut them out.
>
> This actually doesn't sound so difficult, now that I have kind of
> figured
> out how it can be done. It could be a memory hog for large boards,
> however.
>
> Jon
>
>
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