Phil,
The Chamfer at the end of the thread in G76 is specified with the "L" parameter and it is optional. So "L0" would mean no pull out and in the code below l45 would be 45 degree chamfer. The chamfer is specified in the wizard inputing a value for the chamfer. Note the Z differences in the second G32 line of  the code.
You can look at the script to see how that it is is done.

THIS IS G76 CODE WITH 45 DEGREE CHAMFER
---------------------------------------
G0 G40 G18 G80 G50 G90
G00 G53 X0 Z0
T202M6
G00  X1.1
G00 Z0.1
G00 X1
M03 S402
M08
G76 X0.9999 Z-1 Q0 P0.05 J0.0002 L45 H0.0001 I30 C0.1 B0.0002 T0                
M9
M5
M30

THIS IS G32 CODE - 45 DEGREE CHAMFER
----------------------------
(Taper = 0)
(Infeed Angle = 30)
(Total_Depth = 0.0001)
(StartZ = 0.1)
(EndZ = -1)
(Seq = 0 )
(Min_Decrement = 0.0002 )
(Dia Mode )
G0 X1.1 Z0.1
G0 X1
(Min decremant being used)
(Last Pass ID_OD = 1)
(Decrement = -0.0001 pass 1)
G01 Z0.1
G32 X1.0001 Z0.1 F0.05
G32 X1.0001 Z-0.9938 F0.05
G01 X1.1 Z-1 F0.05
G00 X1.1 Z0.1
G00 X1
( Last pass at depth of 0.0002)
G01 Z0.1
G32 X0.9999 Z0.1 F0.05
G32 X0.9999 Z-0.9938 F0.05
G01 X1.1 Z-1 F0.05
G00 X1.1 Z0.1
G00 X1
G00 X1.1 Z0.1

THIS IS G32 CODE WITH 0 DEGREE CHAMFER
--------------------------------------
(Taper = 0)
(Infeed Angle = 30)
(Total_Depth = 0.0001)
(StartZ = 0.1)
(EndZ = -1)
(Seq = 0 )
(Min_Decrement = 0.0002 )
(Dia Mode )
G0 X1.1 Z0.1
G0 X1
(Min decremant being used)
(Last Pass ID_OD = 1)
(Decrement = -0.0001 pass 1)
G01 Z0.1
G32 X1.0001 Z0.1 F0.05
G32 X1.0001 Z-1 F0.05
G01 X1.1 Z-1 F0.05
G00 X1.1 Z0.1
G00 X1
( Last pass at depth of 0.0002)
G01 Z0.1
G32 X0.9999 Z0.1 F0.05
G32 X0.9999 Z-1 F0.05
G01 X1.1 Z-1 F0.05
G00 X1.1 Z0.1
G00 X1
G00 X1.1 Z0.1

RICH

Hood thanks

Here is my G76 code X9.853 Z-12. Q02 P1.75 H0.1 I29 L29 C.100 B0. T0. J0.05

Apart from optional differences nothing major seems to be wrong ?

Phil

Looks fine, you have the chamfer at 29 degrees so it will start the retract 29 degrees before the thread is due to exit. Only other thing I see is your spring pass is defined as 02, doubt if that would cause any problems but I would just have 2.

Hood

Hood thanks for your help

Maybe the Holy Grail of Rev4 wil cure it. 

Phil

Keep in mind, the retract or chamfer angle is in"angle of revolution".....or a "rotational angle".
Not actually a chamfer like I thought.
L90 would retract over 1/4 of a revolution, L360 would be 1 rev., 720, two revs. and so on.
Graham mentioned earlier that the only way to get a nice gradual radial retraction without gutting the groove all the way around the part is to run it sloooowwwww as the acceleration of the X axis retracting will "lag" causing the ringing.
Others mention cutting the threads to a relief groove.
I'll try to find the post.
RC

Here is the topic:

http://www.machsupport.com/forum/index.php/topic,5250.msg36097/topicseen.html#msg36097

RC

Rich your reply no 10 sorry did not see that till after Hood's.

Thanks

Overloaded thanks to you for that reply 14/15 that was a good explanation.

One thing i have learned is that there is a lot to learn.     

Phil

Everyday is a learning day. It never stops and when it does, well, it's cold 6' down!  
RICH