Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 567)

Compound Turning Routines
Chapter 24
24-3
Case 1:
A Case 1 G73 roughing routine is defined when the workpiece contour has
no pockets. The following constraints must be met in order to successfully
perform a Case 1 contouring routine:
The first block of the contour program must command motion in only
the X axis. No Z axis motion is permitted in the first block of the
contour program.
The workpiece contour either continuously increases or continuously
decreases in both the X and Z axis except for the first block of the
workpiece contour program.
The first contour point in the contour blocks must be closer to the
spindle centerline than the last contour point.
Case 2:
A Case 2 G73 roughing routine is defined when a workpiece contour
contains a pocket. The following constraints must be met in order to
successfully perform a Case 2 contouring routine:
The first block of the workpiece 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 X axis after
the first contour block. The workpiece contour must either continuously
increase or continuously decrease along the Z 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 centerline 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 centerline than the second programmed endpoint. The
last programmed endpoint must be farther away from the spindle
centerline than the next to last programmed endpoint.