id threads

[ZWM51]

Have a cnc lathe with fanuc o-t controller. Having trouble programing id threading cycle. Using a G76 threading cycle. Need help with id threads in mild steel. Threads are 5/8-11 & M14X2. Can sumbody send a program to me for both?

thanks,
zw

[sinha_nsit]

M14 x 2
First make a bore of 12 mm, then execute the following:
(assuming that Z = 0 is at the right face of the workpiece)
G21 G97;
...
...
G00 Z5;
X11;
G76 P021060 Q100 R0.1;
G76 X14.454 Z-20 P1227 Q300 F2;
G00 X100;
...
...

02: no. of finishing passes
10: chamfer distance = 1.0 x lead of thread (2 mm) = 2 mm
60: angle of thread in degree
Q100: min roughing depth of cut in microns
R0.1: finishing allowance on diameter;
X14.454: root dia for M14
Z-20: length of thread (change as per your requirement)
P1227: thread height of M14 in microns
Q300: first roughing depth of cut in microns
F2: lead

The roughing depth of cut gradually reduces in subsequent cuts, to ensure equal volume removal in each pass. It starts from 0.3 mm (Q300). If internal calculation give a value of less than 0.1 mm, depth of all subsequent cuts are clamped at 0.1 mm (Q100).

All the finishing passes are of the same depth (.05 mm on dia, for the chosen parameters)
You may select different Q values, or R value, to suit your application.

The other program can be written in a similar manner. I do not have inch threading chart with me.