Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 532)

Tool Tip Radius Compensation (TTRC)
Function
Chapter 21
21-48
Figure 21.43
TTRC Interrupted with MDI Blocks
3 MDI blocks
(no compensation
applied)
End-point
of MDI
r
r
Compensation
reinitializes here
G42
Programmed path
Important: If during cutter compensation, you switch out of automatic
mode and either:
generate axis motion in manual mode on an axis in the cutter
compensation plane, or
execute any block in MDI mode,
cutter compensation is re-initialize when you return to automatic mode.
This produces a path that is different from the path that would have been
produced had the manual or MDI operation not been done, even if you
returned the tool to the point of interrupt. In absolute mode the control
returns to the originally compensated path after it executes a block that
contains both axes in the compensation plane. In incremental mode, the
compensated path remains offset by the additional tool radius.
Figure 21.44 illustrates these conditions.