Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 618)

Thread Cutting
Chapter 25
25-18
Figure 25.12
Results of G21 Straight Thread Cutting Example
Z
X
4.3
4.8
10.0
0.5 lead
10.0 5.0
Taper Thread Cutting
This format is for programming a single pass tapered threading cycle:
G21X__Z__I__ F__ ;
E
Where : Is :
X This parameter is the end point of the thread cutting move in the X axis. This parameter may be an incremental or absolute and radius
or diameter value. This is the depth that the X axis moves to before starting the thread cutting pass. This value may be replaced in any
block following the G21 block while the G21 mode is active.
Z This parameter is the end point of the thread cutting pass in the Z axis. This parameter may be an incremental or absolute value.
Z parameters are always entered as radius values.
E F This parameter may be entered by using either an E- or F-word. It represents the thread lead along the axis with the largest
programmed distance to travel to make the thread cut. It is mandatory when cutting any threads.
If the E-word is programmed, its value (sign ignored) is equal to the number of threads per inch or inches per thread (determined in
AMP) regardless of whether inch or metric mode is active at the time.
If the F-word is programmed, its value (sign ignored) is the thread lead in inches per revolution or millimeters per revolution, depending
on the mode in which the control is operating.
I This is the change in radius of the thread (on the X axis) that the threading pass makes as it reaches the end point of the thread cutting
pass. The end point is the X position programmed with the X-word. I is an incremental, signed distance (+ or -) added to the X
parameter to determine the start point of the threading pass on the X axis. If a chamfer is being cut at the end of the thread cutting
pass, it does not affect the value programmed here. This parameter should be entered as if no chamfer was being cut. I parameters are
always entered as radius values regardless of the current mode. I is always an incremental value regardless of the current mode.