The motion command has an invalid target. G2, G3, and G38.2 generates this error... I've come to the conclusion that NX and/or the postprocessor is not producing enough accuracy to satisfy the (IMO) overly strict limits of GRBL. Three solutions that I can think of: Relax GRBL accuracy limits. Is this possible? I really only need total machine accuracy of about 0.5mm. Increase accuracy in gcode. Switch from I,J to R. (But I've had issues with R in the past). The Gcode that triggers the above error: G0 X548.5700 Y1298.5600 M3 S217 ; pen down G4 P0.25 ; wait for pen to lower G1 G2 X546.3200 Y1299.8500 I-1.5000 J.0000 < ERROR X548.5700 Y1298.5600 I.7500 J-1.2900 M3 S10 ; pen up G4 P0.25 ; wait for pen to raise If I throw the above Gcode into CAD, there is an error of about 0.0078mm: I've tried to increase the significant digits and accuracy in NX and post builder, but apparently I can't figure out where to do it. From NX>Manufacture: If I choose List Tool Path, this has higher precision. Here is the code (corresponding to the Gcode above): TLDATA/WEDM,0.5000,25.0000,0.0000 MSYS/0.0000,0.0000,0.0000,1.0000000,0.0000000,0.0000000,0.0000000,1.0000000,0.0000000 $$ centerline data PAINT/PATH PAINT/SPEED,10 PAINT/PATH,DASH SET/UPPER,25.0000,LOWER,0.0000 LOAD/WIRE PAINT/PATH CUTCOM/LEFT,0 PAINT/COLOR,186 FEDRAT/7620.0000 GOTO/548.5663,1298.5557,0.0000,0.0000000,0.0000000,1.0000000 PAINT/COLOR,31 CIRCLE/547.0663,1298.5557,0.0000,0.0000000,0.0000000,1.0000000,1.5000,0.0000000,0.5000,0.5000,0.0000 GOTO/546.3163,1297.2567,0.0000 CIRCLE/547.0663,1298.5557,0.0000,0.0000000,0.0000000,1.0000000,1.5000,0.0000000,0.5000,0.5000,0.0000 GOTO/546.3163,1299.8547,0.0000 CIRCLE/547.0663,1298.5557,0.0000,0.0000000,0.0000000,1.0000000,1.5000,0.0000000,0.5000,0.5000,0.0000 GOTO/548.5663,1298.5557,0.0000 PAINT/SPEED,10 PAINT/TOOL,NOMORE END-OF-PATH So there appears to be loss of precision in the post builder maybe? Anyone have any ideas how to improve precision? Thanks! Wolf
I've found out how to increase precision in NX post builder. It's on the first page: I changed Linear Motion Resolution from 0.01 to 0.001, and was able to run the job without errors. <Beer emoji>
in your image the arc has a radius of 0.64mm. As the radius decreases, the limits of accuracy of the endpoints approach rapidly. The best fix is to change the post to linearize arcs with radius less than bitRadius. Yes, this is common, battled it in Fusion360 as well. Essentially, ALL arcs have errors, but the percentage error for small radii triggers GRBL's error message. Solution: avoid small arcs (-:
Yes this is my understanding, I also try to avoid small arcs. The issue I ran into several times was with offsets from a closed loop, sometimes the arcs would be small.
