Due to G81 gcode is not supported by grbl, i did the script to convert G81 (produced for Cambam) to movements accepted by grbl to make drills.
Usage:
convertDrills.py -i inputfile -o outputfile [-m]
inputfile -> File with cambam gcodes
outputfile -> Outfile with drills converted
-m Just mark the hole (the Z-axis just down 0.5mm)
Example:
python convertDrills.py -i test.nc -o test_modified.nc -m