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

[dfro@xxxxxxxxx]

Bert,

I am very excited that you are working on a dxf exporter for pcb! In my 
opinion, this will open a very large area of pcb fabrication to 
do-it-yourself people. I am sure it will draw thousands of cnc people to 
the geda tools, also. When it is working, I know everyone at cnczone.com 
would like to hear about this. Also, let Phil at pminmo.com know. I am 
sure he would gladly add/feature it on his 
pminmo.com/millingpcbs/milledpcb.htm page.

 > 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).

My programming experience extends to assembly language for avr and pic 
microchips, and some basic html, so currently I can't jump in and help 
with the coding. Also, a question, which will betray my ignorance: what 
does 'HID' mean? Human Interface Device?

 >
 > 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.
 >

I think generating the dxf file would be better than generating g-code. 
That way people can decide on how they will machine the pcb traces in 
their own 2.5 axis cam software. They can put tool changes where they 
need them, they can program tool offset, decide depth of cut, decide 
what is 'island' and what is 'ocean', and any number of other functions 
- all in the cam software. Then the cam software will generate the 
g-code, which is specific to each person's machine and their preferred 
machining process.

Granted, these comments are based on my current understanding of the 
cad-cam-nc software toolchain. I do not have a machine working yet, but 
I have wired up a controller box and have x, y, and z steppers moving 
using emc2 software. I am half way done building a cnc lathe and I am 
modeling my cnc mill design in Rhino 3D.

Thanks,
Dave



Bert Timmerman wrote:
> 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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> 
> 


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