Hi Guys, I figured out what is causing the recurring G02 G03 problems, it's a Mach3 bug.  When the arc starts in the positive X,Y quadrant and ends in a negative one where either X or Y are negative, Mach3 calculates the radius of the curve wrong and gives you an error even though the cnc code is technically correct.

Example:  The gcode below works because the arc begins and ends in the (+) X,Y quadrant.
G94 F1.5
G00 Z0.50
G00 X7.5000 Y1.6000
G01 Z-0.15
G17
G01 X1.6000 Y1.6000
G03 X0.0000 Y0.0000 I0.0000 J-1.6000
G01 X0.0000 Y-6.0000
G00 Z0.50
M02

The gcode below DOESN'T work because the Y-value ends up negative at the end of the arc.
The only difference is all the Y values have been lowered by 1.6.
G94 F1.5
G00 Z0.50
G00 X7.5000 Y0.0000
G01 Z-0.15
G17
G01 X1.6000 Y0.0000
G03 X0.0000 Y-1.6000 I0.0000 J-1.6000
G01 X0.0000 Y-7.6000
G00 Z0.50
M02

Do you have I&J set to Inc or Abs in config window?

Graham

The second code works fine here. How did it fail for you?

(;-) TP