Owner's manual

Coordinate Control
Chapter 13
13-2
To rotate the current work coordinate system, program the following
command.
G68 X__ Y__ Z__ R__;
Where : Is :
X,Y,Z Specify the centerofrotationusingonly the two axiswordsthat are in the
currentactive plane(G17,G18,orG19). Thevalue enteredwith these axis
words representa position in the cu rrentwork coordinatesystem. The values
specified withtheaxiswordsarealwaysabsolute coordinatevalues,the centerof
rotation cannotbespecified asan incrementalposition.
R Specify the angleofrotation that thecoordinate system is to berotated at. Enter
a value inunits ofdegrees. Risalwaysmeasured parallel to the firstmajoraxis
inthecurrentplane. Positive Ris measuredcounterclockwise,anda negativeR
ismeasured clockwise. Ifyoudo notspecifyan angleusingan Rwordinthe
G68 block,thecontroluses the value ofthe “ProgrammablePartRotation”angle
field fromthe rotation table shown infigure Figure 13.6.
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 13.1). The first motion command following a G68 block cannot
be a circular m ove.
Any unnecessary parameters in the G68 block are ignored. Any G codes
other t hen a plane selection (G17, G18, or G19) or a change from absolute
or incremental mode (G90, or G91) specified in a G68 block will result in
an error.
The G68 block will not create any axes motion. Position displays change
due to the a lteration of the work coordinate system.
Any rotation of the work coordinate system by programming a G68
command will rotate only the currently active work coordinate system.
When changing to a different work coordinate system, the rotation will not
be applied to the new work coordinate system. When c hanging back to the
rotated coordinate system the rotation will still be 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 13-8. 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.
13.1.1
Rotating the Current Work
Coordinate System (G68,
G69)