Oddly enough, I made a part today and found that I lost a critical step causing a cut error. After examining my Gcode, I got to wondering if my G3 commands were impacting it or it was a laptop glitch. I had been using cambam to convert my dxf to gcode, but apparently I didn’t have mach3 as a post processor selected. Mach3 apparently converts g2/3 from arcs to lines and I use it to test the code before I use it on the Xcarve. I just re-generated the code and now the output has no g2/g3 arcs, but individual G1 lines instead I haven’t remade the part but suspect that this will improve this particular part. So while GRbl seems to accept g2/g3 commands, possibly you need to look at your post processor setting or even check to see what $12 is set at and if you need to make it smaller.