HEIDENHAIN NC 124 - Manual (Page 12)

1 Fundamentals of Positioning
12 TNC 124
Y
X
Z
Example: Coordinates of hole 1 :
X = 10 mm
Y = 5 mm
Z = 0 mm (hole depth: Z = – 5 mm)
The datum of the Cartesian coordinate system
is located 10 mm from hole 1 on the X axis and
5 mm from it in the Y axis (in negative direction).
The TNC's probing functions facilitate finding and setting datums.
Y
X
Z
1
10
5
Fig. 1.4: The workpiece datum represents
the origin of the Cartesian coordi-
nate system
Fig. 1.5: Hole 1 defines the coordinate
system
Datums and positions
Setting the datum
The workpiece drawing identifies a certain point on the workpiece
(usually a corner) as the “absolute datum” and perhaps one or more
other points as relative datums. The datum setting procedure estab-
lishes 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 value (e.g., to compensate
the tool radius).