Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 579)

Cylindrical Grinding Fixed Cycles
Chapter 17
17-5
Reciprocation
ATTENTION: Reciprocation differs from conventional axis
motion in that the reciprocating axis has no final destination.
Once axis reciprocation begins, it continues through program
block execution until stopped by a G80, an end of program
(M02, M30, M99), or an emergency stop. This means pressing
single block or cycle stop does not necessarily stop the
reciprocating axis.
Important: You can alter the motion of the reciprocating axis significantly
through the control’s PAL program. This can affect cycle operation. See
your PAL reference manual and/or the literature prepared by your system
installer.
Important: The reciprocating axis cannot be mirrored (G51.1) and cannot
be rotated (G68) before or during reciprocation.
The reciprocating axis is the axis that sweeps back and forth across the part
surface. For the G81 cycle (reciprocation without fixed cycle), the
reciprocation axis is whichever axis is programmed in the G81 block.
Only one axis name can be programmed in a G81 block.
For the cylindrical grinding cycles, the reciprocation axis may or may not
be an axis in the active plane. Different grinding cycles can use different
axes for reciprocation even if the active plane does not change. Most of
the cylindrical grinding cycles do not use a reciprocating axis.
The reciprocating motion is divided into a primary reversal and a
secondary reversal. The reversal points of the primary and secondary
reciprocation moves are defined by the numeric values associated with the
reciprocating axis name and the reciprocating axis integrand. Reversal
points can be an incremental distance from the start point (G91 active), or
an absolute position (G90 active).
Important: If your reciprocating axis is configured as a diameter axis in
AMP, your reciprocation reversal points are altered by radius or diameter
mode (G07/G08).
You can command axis motion while reciprocation mode is active. If the
axis to be moved is independent of the reciprocation, then motion begins as
soon as the control executes the block.