User's Manual

PMAC User Manual
Writing Programs for PMAC 193
Line to Line Line to Arc
A
rc to Arc
Arc to Line
Removing Compensation – Outside Corner
Line
Line
Programmed
Path
Tool Center
Path
Line
Line
Arc
r
r
Spiral
Arc
Programmed
Path
Tool Center
Path
Arc
Arc
r
r
Line
Line
Programmed
Path
Tool Center
Path
Spiral
Arc
r
r
Line
Line
Programmed
Path
Tool Center
Path
Arc
Arc
r
r
Arc
Arc
CC0 CC0
CC0 CC0
Figure 48 Removing Compensation – Outside Corner
Note that this behavior is different from changing the magnitude of the compensation radius to zero while
leaving compensation active. An arc move is always added at the corner, regardless of the setting of I89.
This ensures that the lead-out move will never cut into the last fully compensated move.
Failures in Cutter Compensation
It is possible to give PMAC a program sequence in which the cutter compensation algorithm will fail, not
producing desired results. There are three types of reasons the compensation can fail.
Inability to Calculate Through Corner
First, if PMAC cannot see ahead far enough in the program to find the next move with a component in the
plane of compensation before the present move is calculated, then it will not be able to compute the
intersection point between the two moves. This can happen for several reasons:
• There is a move with no component in the plane of compensation (i.e., perpendicular to the plane of
compensation, as in a Z-axis-only move during XY compensation) before the next move in the plane
of compensation.
• There is more than one DWELL before the next move in the plane of compensation.
• Program logic causes a break in blending moves (e.g., looping twice through a WHILE loop).
If PMAC cannot find the next move in time, it will end the current move as if the intersection with the
next move would form an outside corner. If the next move, when found, does create an outside corner, or
continues straight on, compensation will be correct. On an outside corner, an arc move is always added at
the corner, regardless of the setting of I89. However, if the next move creates an inside corner, the path
will have overcut into the corner. In this case, PMAC will then move to the correct intersection position
and continue with the next move, leaving the over cutting localized to the corner.