Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 340)

Coordinate Control
Chapter 11
11-24
To rotate the current work coordinate system, program this command:
G68 X__ Z__ R__;
Where : Is:
X, Z the center of rotation using only the two axis words that are in the current active
plane (G17, G18, or G19). The value entered with these axis words represent a
position in the current work coordinate system. The values specified with the
axis words are always absolute coordinate values, the center of rotation cannot
be specified as an incremental position.
R the angle of rotation that the coordinate system is to be rotated at. Enter a value
in units of degrees. R is always measured parallel to the first major axis in the
current plane. Positive R is measured counter clockwise, and a negative R is
measured clockwise. If you do not specify an angle using an R word in the G68
block, the control uses the value of the “Programmable Part Rotation” angle field
from the rotation table shown on page 11-30.
Important: If the first motion command following the G68 command is an
incremental move, the center of rotation as described in the G68 command
is ignored and the coordinate system is rotated about its zero point (see
Example 11.10). The first motion command following a G68 block cannot
be a circular move.
The control ignores any unnecessary parameters in the G68 block. Any G
codes other than a plane selection (G17, G18, or G19) or a change from
absolute or incremental mode (G90, or G91) specified in a G68 block
results in an error.
The G68 block does not create any axes motion. Position displays change
due to the alteration of the work coordinate system.
Any rotation of the work coordinate system by programming a G68
command rotates only the currently active work coordinate system. When
changing to a different work coordinate system, the rotation does not apply
to the new work coordinate system. When changing back to the rotated
coordinate system, the rotation is still in effect.
If you do not program an R word in the G68 block, the value of the angle
for programmed rotation is taken from the part rotation screen. Access this
screen as described for external part rotation on page 11-30. The last field
on this screen is the programmable part rotation angle. This angle is only
used when the R word is excluded in the G68 block.
11.6.1
Rotating the Current Work
Coordinate System (G68,
G69)