Setting the datum, 1 f u ndamentals of p o sitioning – HEIDENHAIN TNC 406 User Manual
Page 68
HEIDENHAIN TNC 406, TNC 416
47
4.1 F
u
ndamentals of P
o
sitioning
Setting the datum
The production drawing identifies a certain form element of the
workpiece (usually a corner) as the absolute datum, and usually one or
more form elements as relative datums. Through the datum setting
process, the origin of the absolute or relative coordinate systems is set
to these datums: The workpiece – aligned to the machine axes – is
brought into a certain position relative to the electrode, and the display
is set to zero or the appropriate position value (i.e., to account for the
electrode radius) (see „Datum Setting” on page 22).
Example
The workpiece drawing at right shows holes (
1
to
4
) whose
dimensions are shown with respect to an absolute datum with the
coordinates X=0, Y=0. The holes (
5
to
7
) are dimensioned with respect
to a relative datum with the absolute coordinates X=450, Y=750. With
the DATUM SHIFT cycle you can temporarily set the datum to the
position X=450, Y=750, to be able to program the holes (
5
to
7
)
without further calculations.
Y
X
Z
MAX
MIN
X
Y
325
320
0
450
900
950
150
-150
750
0
300
±
0,
1
11
12
15
13
14
16
17