Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 606)

Using Post Milling Cycles
Chapter 23
23-12
Figure 23.4
Circular Post Finishing Using G88.4
Y
X
FINISH CUT
R
r
POST
(X, Y)
Q
Important: The tool should be positioned near the center of the post prior
to the G88.4 block. The Z coordinate of this position determines the initial
Z level or top of the pocket. This is the pre-cycle position of the tool. The
pre-cycle position must be at some depth other than the cycles
programmed final depth or an error is generated.
From the pre-cycle position, the control simultaneously raises the tool by
the clearance amount (AMP selectable, refer to the literature provided by
your system installer) while moving it to the center of the circular post
specified by the X and Y parameters. This simultaneous move takes place
at the rapid feedrate.
Except for the shape of the post, the rest of the circular post finishing cycle
is identical to that of a rectangular post finishing cycle.
END OF CHAPTER