[Gandoril]

Hello All,

I've been beating my head against a wall to try and figure all of this out and haven't gotten anywhere, so I figured I would post here for help. I just recently started using a FANUC 31ib and I am not really familiar with how the G76 two line code works. The machine was setup with a program from a Miyano tech (posted below) but I can't seem to match the logic between what I've read on G76 and what he gave us. The thread it makes passes gauges, but I can't understand why those numbers work. To me it looks like a combo of metric and standard inputs, and I didn't think you could do that in the same line of code.

I get what the X, Z, and F values are. The P value makes sense except for the 55, since its a 60deg thread. The two Q's, P and R I'm lost on. I've seen so many conflicting explanations as to what those values are supposed to be.


Original code from Miyano tech
G76 P020055 Q30 R5
G76 X.424 Z-.7 P272 Q120 F.03846

Info for the thread (Inch)
.482-26 Preplate Thread
MAJOR .4802 - .4724
PITCH .4554 - .4498
MINOR .4327

Any help in understanding this would be greatly appreciated.

[sinha_nsit]

Normally, last two digits of P is thread angle, 60 deg in this case. However, a lower value can also be used. In such a case, the trailing edge also will cut some material.

P in the second block is height of thread, in least input increment.
Q in the second block is the first depth of cut, in least input increment.
Q in the first block is the minimum depth of cut,in least input increment.
R is finishing allowance. It is in least input increment on some machines.

[Gandoril]

So would this be correct according to the info below?

G76 P020060 Q001 R.001
G76 X.4241 Z-.7 P00218 Q010 F.03846

Q(1) = .001" min depth of cut
R = .001" for finishing cut
P(2) = .0218" (.4763 - .4327)/2 (major avg-minor)/2
Q(2) = .010" first cutting depth

[sinha_nsit]

The least input increment in inch mode is 0.0001
Therefore,it should be
G76 P020060 Q0010 R.001
G76 X.4241 Z-.7 P0218 Q0100 F.03846
which is equivalent to (leading zeroes can be omitted)
G76 P020060 Q10 R.001
G76 X.4241 Z-.7 P218 Q100 F.03846