HEIDENHAIN TNC 360 ISO Programming - Manual (Page 26)

TNC 360 1-9
1 Introduction
Fig. 1.12: Polar coordinates and their associated reference axes
1.2 Fundamentals of NC
Fig. 1.13: 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 coordinate 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 compensate the tool radius).
Y
Z
X
0
°
+
I
J
J
Y
Z
X
0
°
+
K
Y
Z
X
I
0
°
+
K
Setting the pole
The pole 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
I, J +X
J, K +Y
K, I +Z