Double-Lead Thread - Milltronics CNC Lathe

• 2" - 4 Double Lead Thread
• machine: Milltronics ML26
• material: 4140

We ran this 2" - 4 TPI on our Milltronics ML26 lathe to proof the controllers proprietary G76 canned cycle. Our goal was to achieve a double lead thread for an upcoming job.

The G76 cycle format for this particular controller is similar to Fanuc, however it has machine specific preparatory commands (see block numbers N37-N40) -  The machine is also limited to one block, it does not support a two block format.  The unique ability of this controller is the included "Q" parameter seen below. This "Q" parameter controls the shift angle of the thread start position used for multiple threads, i.e. shift 180 deg, 120 deg etc. 0 deg thru 360 deg. are allowed - example: Q0. for zero deg., Q180. for 180 deg., etc.

Here is a truncated program as the second lead would be machined after running the first with the "Q" parameter set to 0.

(TOOL #7 60 DEG. 1/8  0.003 RADTHREADING )
N30 M01
N31 T0707 M06
N32 M41
N33 G50 S200
N34 G97 S50 M03
N35 M08
N36 G00 X2.1 Z1.
N37 P103=0                  Chamfer Length: Length of chamfer on the end of thread.
N38 P104=90.00           Chamfer Angle:  The angle of the chamfer on the end of the thread.
N39 P130=0                  Minimum Cut:    (Radius value)   
N40 P131=1                  Finish Passes:    The last pass can be repeated a number of times.  
N41 G01 X2. F.5
N42 G76 X1.75 Z-4. I0. K.125 D.015 A60. Q180. P1 F.5
N43 G00 X20. M9
N44 G00 Z5. M5
N45 M30