Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 571)

Compound Turning Routines
Chapter 24
24-7
The G73 roughing routine activates the Tool Tip Radius Compensation
(TTRC) function regardless of whether it was active prior to the roughing
routine. If TTRC was not active, the roughing routine uses the tool tip
radius data of the previously programmed T-word. At the end of the
roughing routine, TTRC is cancelled unless it was active prior to the
roughing routine.
In Example 24.1, the workpiece contour blocks are blocks N11 - N14.
Example 24.1
Typical G73 Block Followed By Blocks Defining Final Contour
N005 G73 P11 Q14 U.2 W.2 D.12 F10.S210;
.
.
N010 M30;
N011 X25;
N012 X55 Z40;
N013 X65 Z35;
N014 X70 Z5;
The finish allowance words (U and W) in the G73 block are signed values
dependent on the workpiece contours. Figure 24.4 illustrates this with the
workpiece contour blocks generating the motions from point A to point C.