Remove all copper that isn't in gerber file

[synthead]

Please fill this out:

pcb2gcode version (run pcb2gcode --version to see this):

$ pcb2gcode --version
2.2.2
Git commit: latest
Boost: 107500
Gerbv: 2.7A
Geos: Not installed

What did you try (include command-line arguments):

pcb2gcode \
  --metric \
  --metricoutput \
  --zero-start \
  --zsafe 0.5 \
  --zchange 0.5 \
  --front *-F_Cu.gbr \
    --zwork -0.03 \
    --mill-feed 200 \
    --mill-speed 1000 \
    --offset 0.06 \
  --drill *.drl \
    --zdrill -3 \
    --drill-feed 200 \
    --drill-speed 1000 \
  --outline *-Edge_Cuts.gbr \
     --zcut -3 \
     --cut-feed 200 \
     --cut-speed 50 \
     --cutter-diameter 0.5 \
     --cut-infeed 3 \
     --bridges 1 \
     --zbridges -0.08 \
  --output-dir gcode

What happenned:

Copper that does not exist in gerber file is left on the PCB.

What did you expect to happen:

Copper that does not exist in gerber file is cut from the PCB.

Please attach your input files and relevant output files and images. Don't forget to include your millproject file and gerbers!

I have a gerber file that looks like this:

The keepout area for the copper fill is important because the SD card slot that will live on the PCB has exposed copper pins:

However, the resulting gcode from the command above leaves the copper on the PCB:

How can I mill away the keepout area?

Here is the gerber file: 649-10067847-001RLF-breakout-F_Cu.gbr.zip

[synthead]

Seems related to https://github.com/pcb2gcode/pcb2gcode/issues/391.

[eyal0]

Yup, it's related. Have you tried the isolation-width option or the extra-passes option? Maybe those will be good enough?

I can't think of a reliable way to indicate which parts of the PCB should entirely cleared away versus those that just need isolation.

[eyal0]

I just thought, by the way: If you have regions that you want to mill away entirely, you can put them on another layer and then use the invert-gerbers option to mill away a shape.

So you'll want to run pcb2gcode twice: Once with your gerber and then once again with your shape that you want to mill away and with the invert-gerbers option on. You should make sure to either use the zero-start option or have Edge-Cuts specified (or both), so that the two runs of pcb2gocde will create milling paths with the same alignment.

I hope that makes sense!

[sybrenstuvel]

I just thought, by the way: If you have regions that you want to mill away entirely, you can put them on another layer and then use the invert-gerbers option to mill away a shape.

This works fine for me to remove, say, copper in a rectangular area. However, for situations like these, it's getting a lot trickier:

Here the 230V traces need more clearance than the 12V ones.

[eyal0]

Another way, I forgot to mention, you can specify multiple passes. It will cause it to mill further and further from the trace. This will eventually clear out the whole thing. I don't recall if you tried this...

https://github.com/pcb2gcode/pcb2gcode/wiki/Options:-Milling#--isolation-width-prefer-this-instead-of-the-old---extra-passes

[sybrenstuvel]

The problem is that the low voltage traces need 0.4mm clearance, and the high voltage ones need 2mm. How would I specify which trace gets which clearance?

[eyal0]

If those low-voltage traces get too much clearance, is that a problem? The milling will take longer but otherwise, is there any affect on the board?

Also, if you're anyway doing a ground fill then the extra milling will end where the ground pour starts so it limits itself.

[sybrenstuvel]

Oooooh that works well! This is with --isolation-width 2.0:

Is there any reason to not use --isolation-width 1000 for all projects?

[eyal0]

Some users don't have a ground pour so it would be unnecessarily too much milling.