G71 type I and type II cycles

[sinha_nsit]

Earlier, there was only type I cycle (I think so). Type II cycle was introduced to take care of undercuts or pockets along the length of the job. The control identifies these two cycles on the basis of whether only X is programmed in the P block, or both X and Z are programmed. Earlier, Z was not allowed in the P block (in type I cycle). My question is that, if we program both X and Z in the P block, for a job which has monotonic increase in both X and Z (i.e., has no undercuts, hence suitable for type I cycle), what will happen?

[Geof]

I don't know about any other machine but on a Haas nothing unusual happens if you have X and Z in the P block; the cycle runs fine whether it is monotonic or non-monotonic.

[CNCRim]

nothing should working fine.

[sinha_nsit]

Fanuc 0i manual says in G71 type II section:
"The offset of the tool tip radius is not added to finishing allowances. In turning, the offset of the tool tip radius is assumed to be zero."
Does it mean that radius compensation (G41/42) is not possible in type II turning?

[Geof]

On some machines tip compensation is not active during the G71 but is applied in the G70 cycle. It is necessary to make the finish allowance large enough to include the compensation amount. As far as I know this applies to both type I and II.

[udrııl79]

examples
G71 TYPE 2

O1234
G97M3S1500
T0202
G0 X71 Z1

G71 U3 R1
G71 P1 Q2 U1 W0,5 F0,25

N1 G0 X50 W0,1

G1 Z0.
X60 Z-5
Z-20
X57 Z-23 **********
Z-30 *********

N2 G1 X70
G0 X150 Z200

M30


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