HEIDENHAIN TNC 360 User Manual - Manual (Page 27)

TNC 360 1-9
1 Introduction
Setting a pole at circle center CC
The pole (circle center) is defined by setting two Cartesian coordinates.
These two coordinates also determine the reference axis for the polar
angle PA.
Coordinates of the pole Reference axis of the angle
X Y +X
Y Z +Y
Z X +Z
Fig. 1.13: Polar coordinates and their associated reference axes
1.2 Fundamentals of NC
Y
Z
X
CC
0
°
+
CC
Y
Z
X
0
°
+
Y
Z
X
CC
0
°
+
Fig. 1.14: The workpiece datum serves as
the origin of the Cartesian
coordinate system
Y
X
Z
Setting the datum
The workpiece drawing identifies a certain prominent point on the work-
piece (usually a corner) as the "absolute datum" and perhaps one or more
other points as relative datums. The process of datum setting establishes
these points as the origin of the absolute or relative coordi-nate systems:
The workpiece, which is aligned with the machine axes, is moved to a
certain position relative to the tool and the display is set either to zero or
to another appropriate position value (e.g. to compen-sate the tool radius).