I'm trying to calculate the number of threading passes my first use of a G76 threading cycle will make for a 1-4/3 x 12 UN 2A external thread.
I have no basis for comparison, having never cut threads before, but the number I'm comming up with seems large to me. Could someone check this???
Here are my G76 blocks:
G76 P020060 Q20 R0.
G76 X1.6398 Z-2.275 P511 Q120 F.083333
The formula I have is from Peter Smid (CNC Programming Hdbk):
n = ((P-R)/Q) ^ 2
where:
n = Number of threading passes
P = Depth of thread per side
R = Depth of the last threading pass
Q = Depth of the first threading pass
So I get:
number of passes = ((0.0511 - 0.002) / .012) ^ 2
number of passes = 16.74
which seems like an aweful lot. Is that right????
I'm thinking the Q value in the first line of the G76 format gives the depth of the last threading pass (R in my formula), and
I'm thinking the Q value in the second line of the G76 format gives the depth of the first threading pass.
Thanks