I,J,K
when using G17 (XY Plane), the I's and J's represent incremental values in either the X or Y axis (I = X, J = Y) from the center point of the radius to the end point... I tend to program in longhand, adding more codes than perhaps I need, but it keeps things clear for me should I screw up.... a sample program might look like this...
O100 (SAMPLE PROGRAM)
G0 G90 G80 G40 G49 G17 (my safeline)
E48 X0 Y0 (safe toolchange location as my fadal likes to spit out tools)
M6 T5
E3 H5 D5 Z2.
X-3. Y-2.
G41 X-2.5 Y-1.5 (CC on)
Z.1
M1
M3 M8 S2000
G1 Z-.5 F20.
Y0
G3 X0 Y0 I1.25 J0 F15. (the center of the radius is actually at X-1.25, but this value is incremental)
G1 Y-1.5 F20.
Z.1 M5 M9
E48 X0 Y0 G0
G53 Z0
M6 T5 (i have to add this at the end, otherwise the Z axis rapids to the upper stop at M2, for some reason)
M2
hope this helps some
M4
No, really, just my .002"