Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 566)

Cutter Diameter Compensation
(G40, G41, G42)
Chapter 21
21-48
Figure 21.45
Cutter Compensation Re-Initialized after a Manual or MDI Operation.
Manually jog axes (or any MDI
execution) and return to the
compensated path.
Cutter Compensation is re-initialized here. The control assumes that the
current position is a programmed position at the point of re-initialization.
Consequently, after the initialization, tool compensation is offset by twice the
tool radius.
Tool Radius
Over Compensated Path
(after MDI/Manual Interrupt)
Original Compensated Path
(had no interruption occurred)
Programmed Path
Use the Jog Retract feature if you must jog the axes away from a
compensated path. Jog retract prevents the overcompensation from
occurring.
If you interrupt cutter compensation with a manual or MDI operation and
the next programmed block is a circular block, the control generates an
error when it tries to re-initialize cutter compensation. You can avoid this
by using the jog retract feature instead of manual or MDI when you need
to interrupt cutter compensation.
It is recommended that cutter compensation be cancelled using a G40
command before the execution of a return to or from machine home, or a
return to or from the secondary machine home. This refers to the
operations performed when the control executes either the G28, G29, or
G30 commands as described in section 21.3.
If compensation is not cancelled using a G40 command, the control
automatically, temporarily cancels compensation for the return to machine
home or secondary machine home operations. This is done by using the
move to the intermediate point, designated when the operation is
performed, as an exit move for compensation.
Important: An intermediate point should always be programmed for a
return-to-home operation if cutter compensation is active. If no
intermediate point is specified, the control executes the move prior to the
return-to-home operation as an exit move. This may cause undesired
over-cutting of the part.
21.6.6
Moving To/From Machine
Home