FlatCAM is a program for preparing CNC jobs for making PCBs on a CNC router. Among other things, it can take a Gerber file generated by your favorite PCB CAD program, and create G-Code for Isolation routing.

double sided shell script used for Loop Arduino Shield example from [fritzing](Link URL)http://fritzing.org/

#!python


new
set_sys units MM


# ######### BOTTOM layer

# LOAD
open_gerber /path/to/Gerber/Loop_contour.gm1  -outname BCu_margin
open_gerber /path/to/Gerber/Loop_copperBottom.gbl -outname BCu
open_excellon /path/to/Gerber/Loop_drill.txt -outname BCu_drills

#MIRROR
mirror BCu -box BCu_margin -axis X
mirror BCu_drills -box BCu_margin -axis X

#ALIGNHOLES
aligndrill BCu_margin -dia 3 -box BCu_margin -grid 10 -gridoffset 5 -axisoffset 0  -axis X

#CUTOUT
isolate BCu_margin -dia 3 -overlap 1
exteriors BCu_margin_iso -outname BCu_margin_iso_exterior
delete BCu_margin_iso
geocutout BCu_margin_iso_exterior -dia 3 -gapsize 0.2 -gaps 4

#ISOLATE TRACES
exteriors BCu_margin -outname BCu_exterior
isolate BCu -dia 0.8 -overlap 1

#JOIN TRACES and basic exterior
join_geometries BCu_join_iso BCu_iso BCu_exterior

#CNCJOBS
drillcncjob BCu_drills -tools 100,101,102,103,104 -drillz -2 -travelz 2 -feedrate 5 -outname BCu_drills_0.8
drillcncjob BCu_margin_aligndrill -tools 1 -drillz -2 -travelz 2 -feedrate 5 -outname BCu_drills_3

cncjob BCu_join_iso -tooldia 0.6
#cncjob BCu_margin_cutout -tooldia 3
cncjob BCu_margin_iso_exterior -tooldia 3



#GENERATE GCODE

write_gcode BCu_join_iso_cnc /path/to/Gerber/output/Loop-BCu.pngc
write_gcode BCu_margin_iso_exterior_cnc /path/to/Gerber/output/Loop-BCu-Margin.ngc
write_gcode BCu_drills_0.8 /path/to/Gerber/output/Loop-BCu.drl_0.8.ngc
write_gcode BCu_drills_3 /path/to/Gerber/output/Loop-BCu.drl_3.ngc



# ######### TOP layer


# LOAD
open_gerber /path/to/Gerber/Loop_contour.gm1  -outname FCu_margin
open_gerber /path/to/Gerber/Loop_copperTop.gtl -outname FCu
open_excellon /path/to/Gerber/Loop_drill.txt -outname FCu_drills

#ALIGNHOLES
aligndrill FCu_margin -dia 3 -box FCu_margin -grid 10 -gridoffset 5 -axisoffset 0  -axis X

#CUTOUT
isolate FCu_margin -dia 3 -overlap 1
exteriors FCu_margin_iso -outname FCu_margin_iso_exterior
delete FCu_margin_iso
geocutout FCu_margin_iso_exterior -dia 3 -gapsize 0.2 -gaps 4

#ISOLATE TRACES
exteriors FCu_margin -outname FCu_exterior
isolate FCu -dia 0.8 -overlap 1

#JOIN TRACES and basic exterior
join_geometries FCu_join_iso FCu_iso FCu_exterior

#CNCJOBS
drillcncjob FCu_drills -tools 100,101,102,103,104 -drillz -2 -travelz 2 -feedrate 5 -outname FCu_drills_0.8
drillcncjob FCu_margin_aligndrill -tools 1 -drillz -2 -travelz 2 -feedrate 5 -outname FCu_drills_3

cncjob FCu_join_iso -tooldia 0.6
#cncjob FCu_margin_cutout -tooldia 3
cncjob FCu_margin_iso_exterior -tooldia 3



#GENERATE GCODE

write_gcode FCu_join_iso_cnc /path/to/Gerber/output/Loop-FCu.pngc
write_gcode FCu_margin_iso_exterior_cnc /path/to/Gerber/output/Loop-FCu-Margin.ngc
write_gcode FCu_drills_0.8 /path/to/Gerber/output/Loop-FCu.drl_0.8.ngc
write_gcode FCu_drills_3 /path/to/Gerber/output/Loop-FCu.drl_3.ngc