Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 581)

Compound Turning Routines
Chapter 24
24-17
Case 2:
A Case 2 G74 rough facing routine is defined when a workpiece contour
contains a pocket. The following constraints must be met in order to
successfully perform a Case 2 rough facing routine:
The first block of the contour program must contain motion in both the
X and Z axis (the move from the start point to the first contour point
must have motion in both axes).
The workpiece contour may increase or decrease along the Z axis after
the first contour block. The workpiece contour must either continuously
increase or continuously decrease along the X axis after the first contour
block.
The first contour point of the contour blocks must be farther away (or at
least equidistant) from the spindle face than the last contour point
The first and last contour blocks must define beginning and ending sides
to the contour. The first programmed endpoint must be farther away
from the spindle face than the second programmed endpoint. The last
programmed endpoint must be farther away from the spindle face than
the next to last programmed endpoint.
Figure 24.13
Workpiece Finish Contour Case 1 and Case 2 (G74)
Start
point
Start Point
Case 1 Case 2
Z
Z
X X
The G74 block is programmed with the following format:
G74P__Q__U__W__I__K__D__R__F__S__T__;