1/4 NPT External thread program

[JerryH]

Can someone help me with programming 1/4 npt external using G76 (fanuc O-T). I do not know what values to put in for the thread dimensions. Thanks!

[CNCRim]

.54 dia start point with 1.75deg per side. Is it help.

[Tenextoolco]

I'm threading 1/4 npt threads on a fanuc ot controled cnc lathe. Can anyone give me some help on the second line of info using G76?

[Geof]

Lead is 18 threads per inch, taper is 0.0625" per inch diameter measure, finish diameter is around 0.56", length is around 1/2".

[g-codeguy]

Thread ending point figured at center of 16ER 18 NPT insert and L4 dimension from Machinery's Handbook.

Finish turn .016R insert
X.3768Z0
G3X.4065Z-.0062R.021
G1X.5249Z-.0653
X.54Z-.3077
Z-?

Finish turn .031R insert
X.3468Z0
G3X.3977Z-.0105R.036
G1X.5245Z-.0739
X.54Z-.3224
Z-?

Thread 1/4-18 NPT external
X.58Z.3
G76P000155Q30
G76X.467Z-.634P444Q150R-.0291F.05556

Changing starting point or ending point will require R to be modified. R=tan(1+47/60)*(start point + end point) unless both points are the same sign, in which case you would subtract them.

Single block G76
X.58Z.3
G76X.467Z-.634I-.0291K.0444D150F.0556A50.

Did one of these work okay for you?

[g-codeguy]

Apparently my examples didn't work. What did you finally wind up with?