Mills use G17 for standard arcs where the centre point is on the same plane as each point on the arc...
so G17 XY & IJ
G18 XZ & IK
the 3rd axis is sometimes used for creating a helical move
so to correct your program... get rid of G18... or change to G17
G2 is for clockwise movement.... G3 for CCW
plus the M2 should be on the last line, by itself
Try this for G17 .. using IJ
Code:
G21 ; ( inch programming... by itself )
G17 G90 ; ( safety lines.... XY plane, absolute )
M3 S4000 ;
G0 Z0.5 ;
G0 X5.9 Y-0.7 ;
G1 Z-0.7 F50 ;
G02 X4.1 Y-0.7 I-0.9 J1.2 F50 ;
G0 Z0.5 ;
M2 ;
Try this for G17 .. using R
Code:
G21 ; ( inch programming... by itself )
G17 G90 ; ( safety lines.... XY plane, absolute )
M3 S4000 ;
G0 Z0.5 ;
G0 X5.9 Y-0.7 ;
G1 Z-0.7 F50 ;
G02 X4.1 Y-0.7 R1.5 F50 ;
G0 Z0.5 ;
M2 ;
I also stripped trailing zeros, as they are not necessary