G71 G-Code Issue

[ozwes007]

Hi Everyone,
I have been placed in charge of a very old(not old as me btw!) CNC Ann Yang Lathe.
the issue I'm having is to understand the G71 cycle it uses.
The following are an inside an outside sample i have got to work.
It uses Type A G Code according to the documentation.

Now Questions,
1. What brand of G Code is it?
2. Why does a simple two line G71 code not work?(not the Single line type 2 BTW)
3.Can some one explain how to combine multiple steps in this style of G Code?
HAAS and Fanuc don't seem to fit this model in various ways.
First two lines are fine, its just the P to Q lines that are throwing me ATM
And finally does anyone know of an offline G Code generation program that utilizes the bulk of the Canned Lathe Cycles?(Free or at a reasonable price)

Internal(Works Fine)
G71 U0.200 R0.5;
G71 P14 Q15 U-0.200 W0.125;
N14 G00 X89.500 Z0.500;
G01 X89.500 Z0.000;
G01 Z-25.000;
G01 X84.000 Z-25.000;
N15 G01 U-2.000;

External(works Fine)
/* Turn Diamater */
G00 X121.000 Z1.000;
G40;
G71 U0.500 R0.5;
G71 P110 Q150 U0.125 W0.125;
N110 G00 X110.000 Z1.000;
G01 X110.000 Z0.000;
G01 Z-110.000;
G01 X120.000 Z-110.000;
N150 G01 U2.000;
G00 X120.000 Z1.000;
G70 P110 Q150;
G00 Z5.000;
G40;

(Doesn't Work)
G71 U0.125 R0.5
G71 P80 Q90 U0 W0;
N80 X60;
N90 Z-75;

Regards
Wes

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[Heavy_Metal]

Hey Wes,

External(works Fine)
/* Turn Diamater */
G00 X121.000 Z1.000;
G40;
G71 U0.500 R0.5;
G71 P110 Q150 U0.125 W0.125; ( -- add a F... for roughing )
N110 G00 X110.000 Z1.000;
G01 X110.000 Z0.000; ( -- add a F... for G70 finishing )
G01 Z-110.000;
G01 X120.000 Z-110.000;
N150 G01 U2.000;
G00 X120.000 Z1.000;
G70 P110 Q150;
G00 Z5.000;
G40;

(Doesn't Work)
X40. ( add a start diameter )
G71 U0.125 R0.5
G71 P80 Q90 U0 W0; ( -- add a F... for roughing )
N80 X60; ( add a G01 )
N90 Z-75;

Regards.
Heavy_Metal.

[ozwes007]

Thanks Heavy_Metal, however the one that doesn’t work has a prep move the same as the others, I just didn’t put it in. The roughing feed is a standard rate placed at the start of the program. If you need a fine feed it iis placed within the P and Q blocks in this one.
i have found that a G00 move has to be the first move to the first diameter and I think that’s the reason the last example doesn’t work.
its looking like a Haas style code I think.

regards
Wes

[Heavy_Metal]

Thanks Heavy_Metal, however the one that doesn’t work has a prep move the same as the others, I just didn’t put it in. The roughing feed is a standard rate placed at the start of the program. If you need a fine feed it iis placed within the P and Q blocks in this one.
i have found that a G00 move has to be the first move to the first diameter and I think that’s the reason the last example doesn’t work.
its looking like a Haas style code I think.

regards
Wes

We have a Haas NextGen controlled lathe and it has the G71 with one line code, so not like our Fanuc lathes.

[sinha_nsit]

May like to read this for detailed information on Fanuc 2-line G71/G72.