Re: gEDA-user: Would like to use geda tools to make .dxf file for pcb cnc milling.

[Bert Timmerman <bert.timmerman@xxxxxxxxx>]

Hi Dave,

On Fri, 2009-08-14 at 00:12 -0400, dfro@xxxxxxxxx wrote:
> I am sorry if this is a redundant request/question.
> 
> I am currently building a cnc machine on which I would like to mill pcb's.
> 
> Others have worked out a tool chain using eagle:
> http://pminmo.com/millingpcbs/milledpcb.htm
> 
> Is there any interest in a Geda-based alternative? Could it be 
> gschem--pcb/dxf(export) or gschem--pcb--gerbv/dxf(export)? The dxf file 
> would be an outline of all the traces and pads. The traces and pads 
> would be 'islands' that the cnc machine would mill around.
> 

I have made a start for a dxf exporter HID at:

http://github.com/bert/pcb-dxf-hid/tree/master

but somethings have come in between.

If you would like to take development further do not hesitate to clone
and/or send patches, you are welcome :)

If you are willing to open an account on github, you and I can even
share pull requests very easy by means of the github "fork queue" (a
web-based tool monitoring forked of repo's).

> Here, is the tool chain I have tried to get working without success.
> 1. From pcb I export gerber files.
> 2. I load a gerber file in gerbv and export it as a pdf
> 3. I load the pdf in inkscape and save as a dxf file.
> 
> However, when I view the dxf file in qcad or any other cad or cam 
> program, the strokes and objects from inkscape are split into two 
> incomplete and offset images, and the pcb traces are lines with no 
> thickness. Inkscape is turning all strokes(pcb traces) into lines in the 
> dxf file.
> 

In dxf one can use polylines which can have width (*and* thickness in
Z-direction), one can even join all traces of a net into one polyline
(with branches and arcs).

> In inkscape, if I go through the very cumbersome process of individually 
> selecting each stroke(trace) with the 'Edit paths by nodes(F2)' tool, 
> and select 'Path>Stroke to Path' and then combine all the edited paths 
> and objects using 'Path>Union' I can get a dxf file that is an outline 
> of the traces and pads. However, inkscape often adds a little bulge to 
> the end of each stroke. So, it is not a perfect outline. This also takes 
> way too long on anything other than the most simple pcb artwork. So, I 
> am stumped.
> 
> Any interest in adding the dxf export feature to pcb or gerbv? It seems 
> to me that cnc milling of pcb's is becoming viable as a homeshop 
> alternative to all of the other standard methods of fabricating pcb's.
> 

Generating a cnc file (g-codes/m-codes) without dxf would be faster in
any case and less error prone, why not code a cnc exporter ?

Or does one need an intermediate format like dxf which describes the
positive shapes, and not the inverted (copper to remove) shapes and
traces.

Maybe inverted Gerbers are a better starting point.

> thanks,
> Dave
> 
> 

Kind regards,

Bert Timmerman.



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