Its been a while since ive done any programming on the SL-25 they have at work (i can look tomorrow), but it might need a double G72.
CNC Fanuc G72 Canned Cycle Facing
G72 W R
G72 P Q U W
First Block
Parameter Description
W Depth of cut.
R Return value after a cut is complete.
Second Block
Parameter Description
P Contour start block number.
Q Contour end block number.
U Finishing allowance in x-axis.
W Finishing allowance in z-axis.
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