G72 facing - oi TD

[DC800]

Hi all
I'm facing the front & back of a flange on a large casting, can I use g72 to face the back with a left hand tool?
Fanuc oitd on a samsung pl35 lathe
Thanks, dave

[fordav11]

Yes. The W finish allowance is minus in this case and your start point in Z is more minus than the finish point.
You don't give any sizes so I'll make up something for an example....

If the back of the flange is at Z-20.0 (and you have 5mm of material to face off) and the OD start point is dia. 100 and OD end point is dia. 80 ........

G50 S1000
G0 T0101
G96 S100 M3
G0 X200.0 Z-25.0 M8
X102.0
G72 W2.0 R0.5
G72 P10 Q11 U0 W-0.2 F0.25
N10 G0 Z-20.0
G1 X80.0 F0.25
N11 Z-25.0
G70 P10 Q11
G0 X250.0
Z250.0 M9
T0100 M5
M1
M30

[DC800]

Thats great, thanks for the reply.
Will save me a lot of time.

Dave