HELP ILLIGAL G72

i have been trying to run a g72 for a back rad on my romi g20 Fanuc 21i-t every time u run it it says illigal g71-g71 have tried a few different things with the same result not sure what's wrong as never done this before
N4(BACK RAD ROUGH)
G28U0
G28W0
T0404
G97S1000M3
G0Z-29.0
X53.0
G1X30.7F.12
G0X53.0
Z-19.0
G72U0.7R0.5
G72P104Q105U.2W.1F.1
N104G1X50.8F.1
G3X30.8Z-29.0
N105G0X55.0
G28U0
G28W0
M1 any help would be appreciated

Quote:

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Originally Posted by Doink

i have been trying to run a g72 for a back rad on my romi g20 Fanuc 21i-t every time u run it it says illigal g71-g71 have tried a few different things with the same result not sure what's wrong as never done this before
N4(BACK RAD ROUGH)
G28U0
G28W0
T0404
G97S1000M3
G0Z-29.0
X53.0
G1X30.7F.12
G0X53.0
Z-19.0
G72U0.7R0.5
G72P104Q105U.2W.1F.1
N104G1X50.8F.1
G3X30.8Z-29.0
N105G0X55.0
G28U0
G28W0
M1 any help would be appreciated

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You are using G3 (arc move) in N104 (G3 X30.8 Z-29.0), which could be problematic in a G72 cycle.
G72 requires only linear moves (G1, G0)—no arcs (G2/G3). Try breaking the arc into small linear moves.

Nope,

ARC's are no problem for G71/G72, this is actually G71 code not G72.

1st: - when you want G72 change G72 U0.7 R0.5 to G72 W0.7 R0.5 ... U is for G71 / W for G72 !!
2nd: - first move in line after G72 is a Z-move, not X, N104 G1 Z___ F.1
3rd: - add a R-value to your G3 X30.8 Z-29.0 R___ !!

regards.