[vikassahni]

i need to make a cnc program for taper thread on fanuc series Oi Mate TC control.

thread details are : 3/4" NGT Threads, Taper 1:16, Pitch 1.814

a cnc program for this thread will be a big help

thanks

vikas

[sinha_nsit]

I assume you want to make an external thread.
Just give an R-value, with a negative sign, in G92, or in the secind block of G76.
The meaning of R-word is exactly same as that of R-word in G90.
While calculating R-value for G92/G76, consider the specified XZ location in the command block, and the start point of the cycle. Pull-out angle has no effect on this calculation.

[vikassahni]

thanks for ur reply

i would like to share that it is an internal thread

and the tool is moving from large end to small end then how can we use negative value for R

further i would also like to share that i have tried a prgm it worked but the quality of thread is not good though it confirms the gauges

we can also say that the thread formed is very sharp

i m sharing the prgm underneath for ready reference

G28 U0. W0.;
M01;
T0101;
G97 S1700 M3;
G0 X20. Z50. M8;
Z25.;
;
G76 P040060 Q90 R0.03;
G76 X23.5867 Z-25. P1161 Q150 R1.5625 F1.814;
G0 Z50. M9;
G28 U0. W0.;
M30;
%


kindly sugeest if any change to be made to this prgm

thanks once again

vikas

[sinha_nsit]

For internal threads, R would be positive.
Your rpm is too high.
Initial bore dia may not be correct (it should be, OD - pitch of thread).
Check root dia also (it should be, bore dia + 2 x depth of thread).
Consult a handbook for depth of thread.

[vikassahni]

pls let me know the correct rpm for this case

regarding bore size, the plain plug gauge is being confirmed at both the ends

as i have written earlier the thread is very sharp, which parametre should be altered so that desired results are achieved.

as all the figures are calculated with formulas, only the X23.586 is the value i m not very sure off

should i increase this value or decrease to reach the desired result, if yes how what variation should be brought pls tell

and yes thanks once again for your response

vikas

[sinha_nsit]

Low rpm such as 500 may be used.
X23.586 appears to be large. How did you calculate this value? Reduce it to, say, 19.5 and see what you get.
How much is your bore dia?