I appreciate the offers of assistance.
I'm trying to make a fairly simple part - cutting a roughly 2"x3" rectangle (more or less) out of sheet brass. One side has rounded corners, and the other is completely round. Top and bottom are straight. I'm frustrated at the results, not just with the error msg.
Here's one of many versions of G-code that I've tried:
N010 G91.1 G17
N020 G1 G41 X0.1 P0.125
N030 G1 Z+0.0500
N040 G1 X+0.0000 Y+1.1111
N050 G1 Z-0.0050
N060 G2 X+0.0000 Y-1.1111 I0 J-1.1111
N070 G1 Z+0.0500
N080 G1 X+1.0000 Y-0.9675
N090 G1 Z-0.0050
N100 G1 X-1.7500 Y-0.9675
N110 G2 X-2.0000 Y-0.7175 I0 J0.25
N120 G1 X-2.0000 Y+0.7175
N130 G2 X-1.7500 Y+0.9675 I0.25 J0
N140 G1 X+1.0000 Y+0.9675
N150 G1 Z+0.0500
N160 M30
Line N020 is a dummy that I've had to throw in to get rid of the error msg.
I don't know where the top and bottom intersect the arc, so I try to cut them separately. Mach3 doesn't seem to want to do this. When I run this code, it cuts the N040-N060 arc, but then goes to X-500 somewhere, rather than X+1.000. It cuts the rest of the bottom, side and corners correctly, but then stops on the top in the X_500 area. I'm sure it's trying to help, but I don't understand how to control it.
Charley