Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 534)

Tool Tip Radius Compensation (TTRC)
Function
Chapter 21
21-50
specified, the control executes the move prior to the return to home
operation as an exit move. This can cause undesired overcutting of the
part.
If compensation was not cancelled using a G40 command before returning
to machine or secondary home points, the control automatically
re-initializes TTRC for the return from machine or secondary home points.
This is done by using the move to the intermediate point, as designated
when the operation was performed as an entry move for compensation.
Figure 21.45 shows either a G28 or G30 block followed by a G29 block:
Figure 21.45
TTRC During G28, G30, and G29 Blocks
Temporary cancel of
compensation here
at intermediate point
Reference point
Programmed
path
G41
N11 N12
N13
N13’
N14’
N15
N14
r
r r
r
r r
r r