HEIDENHAIN TNC 426 (280 476) Pilot - Manual (Page 7)

8
Fundamentals
Circle Center and Pole: CC
The circle center (CC) must be entered to program circular tool
movements with the path function C (see page 21). CC is also needed
to define the pole for polar coordinates.
CC is entered in Cartesian coordinates*.
An absolutely defined circle center or pole is always measured from
the workpiece datum.
An incrementally defined circle center or pole is always measured
from the last programmed position of the workpiece.
Angle Reference Axis
Angles – such as a polar coordinate angle PA or an angle of rotation
ROT – are measured from the angle reference axis.
Working plane Ref. axis and 0° direction
X/Y X
Y/Z Y
Z/X Z
*Circle center in polar coordinates: See FK programming