Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 548)

Cutter Diameter Compensation
(G40, G41, G42)
Chapter 21
21-30
Except for entry and exit moves, the basic tool paths generated during
cutter compensation are the same for types A and B cutter compensation.
The paths taken are a function of the angle between tool paths (whether
G41 tool-left or G42 tool-right is specified) and the radius of the cutting
tool.
Important: If at any time during the execution of cutter compensation
blocks a block reset is performed, the cutter compensation function is
re-initialized, and the next move acts as an entry move as described in an
earlier section.
Important: When cutting arcs with cutter compensation active, the control
may need to adjust the programmed feedrate to maintain cutting speed.
Refer to Chapter 18 for details on feedrates during cutter compensation.
The control generates extra motion blocks when necessary to keep the
cutting tool in tolerance of the desired tool path. This becomes necessary
when the intersection of tool paths is an outside tool path (as defined in
section 21.0) that has an angle as follows:
between 0 and 90 degrees during cutter compensation left (G41)
between 270 and 360 degrees during cutter compensation right (G42)
21.5
Tool Path During Cutter
Compensation