# FANUC Series 16i/18i/21i-TB Cylindrical Interpolation by the Developed Cylindrical Surface Command Specifications Additional Manual Page 4

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FANUC Series 16i/18i/21i –TB,
Cylindrical interpolation by the developed
cylindrical surface command
Jan.20.2004
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Sheet
and another linear axis. Radius R is used in commands in the same way as general circular
interpolation.
The unit for a radius is not degrees but millimeters (for metric input) or inches (for inch input).
Examples)
Circular interpolation between the Z axis and C axis
For the C axis of parameter No. 1022, 5 (axis parallel with the X axis) is to be set.
In this case, the command for circular interpolation is
G18 Z__C__;
G02 (G03) Z__C__R__;
For the C axis of parameter No. 1022, 6 (axis parallel with the Y axis) may be specified
instead. In this case, however, the command for circular interpolation is
G19 C__Z__;
G02 (G03) Z__C__R__;
To perform tool nose radius compensation in the cylindrical interpolation mode, cancel any
ongoing tool nose radius compensation mode before entering the cylindrical interpolation
mode. Then, start and terminate tool nose radius compensation within the cylindrical
interpolation mode.
Cylindrical interpolation accuracy
In the cylindrical interpolation mode, the amount of travel of a rotary axis specified by an
angle is once internally converted to a distance of a linear axis on the outer surface so that
linear interpolation or circular interpolation can be performed with another axis. After
interpolation, such a distance is converted back to an angle. For this conversion, the amount
of travel is rounded to a least input increment. So when the radius of a cylinder is small, the
actual amount of travel can differ from a specified amount of travel. Note, however, that such
an error is not accumulative.
If manual operation is performed in the cylindrical interpolation mode with manual absolute
on, an error can occur for the reason described above.
×
××
×
=
REVMOTION
R
Command
R
REVMOTION
ceActualDis
π
π
22
22
tan
MOTION REV : The amount of travel per rotation of the rotation axis (Setting value of
parameter No. 1260)