Hi All,
I am having trouble getting G76 to work right!  I am trying to cut a thread with a 5 degree taper, but mach is only cutting a 2.5 degree taper.  I am working in diameter mode but I don't see how that would make it only cut half the angle because it is cutting the correct diameter.  I did try changing the “T” value to 10 and then it cut a 5 degree taper.

Any help would be great! 

Andrew with MachMotion

This is the gcode file I am running!
(***** OD Threading Cycle# 01.13 *****)
G18 G40 G49 G90 G80
T505 M6 H5
G20 (Inch)
G95 (Feed Per Minute Mode)
G97 S1200
M03 (Spindle Forward)
M08 (Flood)
G00 Z0.1
G00 X0.6
G76 X0.5318 Z-1.6 Q3 P0.055555556 J0.008 L0 H0.01 I29.5 C0.1 B0.003 T5
(* End Cycle# 01.13 OD Threading*)
M5 M9
M30

I think tapers in shafts are normally defined in dia so the angle would be double. EG on a boats propellor shaft the normal taper is 1:12, that is an agle of 2.385 degrees per side but you would set the taper attachment of a manual lathe to 4.77 degrees.
Hood

Hood,

Thanks for your help!

Andrew