[paradiddle1]

I have 3 programs that I had setup using g76 and it always ends up over size . I end up adjusting wear offset in X -.011 approx. to get gage to fit or get PD correct.

I am using the minor diameter from machinery hand book and using K value difference between major and minor/2. Spring passes shallow depth etc. I am using walter inserts with sharp point.

On a repeat job I had to fudge the Minor diameter by .012 and it always comes out correct with little or no wear adjustment. 1.50-12 thread.

N6 T404 (THD TOOL)
(1.50 X.12)
( USE GAGE TO CHECK )
( WALTER THREADING INSERT )
( NTS-ER -16 AG60 WXP20)
G50 S1250
G97 S500 M03
G54 G00 X2.1 Z1. M08
G96 S400
G00 X1.6 Z0.1
M24
(PD = 1.4008)
(PD ADJUSTMENT FOR INSERT =.047/2)
(K= NEW PD FOR INSERT)
G76 X1.3773 (X1.4008) Z-1.2 K0.0614 (K.0496) F0.083 D0.003
G00 X2.1
G97 S500 M09
Z1.
G28
M01

[dcoupar]

If I'm not mistaken, according to the Walter catalog, those inserts have a nominal radius of 0.08mm ± 0.05mm.Worst case, the radius would be 0.013mm or 0.0051", so it's very likely that your threads might need fudging.

[djm77]

I've never made a thread yet where I haven't had to adjust my offset in the X. Don't sweat it, you've made the parts right which is all that matters.


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[paradiddle1]

Thanks, I want to teach correctly and most of my 28 years has been with CNC Mill up to 5 axis The CNC lathe has actually been fun because of new learning for me. I left job # 1 with adjusted X so the setup will happen quicker without rerun and test a million times. The other projects/jobs we will know just to play with offset until its ok. I was looking for data in Walter catalog but I must have missed it. Thanks