HEIDENHAIN ND 720 v.3 - Manual (Page 5)

5
Datum setting
The workpiece drawing is used as the basis for machining the
workpiece. To enable the dimensions in the drawing to be converted
into traverse distances of machine axes X, Y and Z, each drawing
dimension requires a datum or reference point on the workpiece
(since a position can only be defined in relationship to another
position).
The workpiece drawing always indicates one absolute datum (the
datum for absolute dimensions). However, it may contain additional
relative datums.
In the context of a numerical position display unit, datum setting
means bringing the workpiece and the tool into a defined position in
relation to each other and then setting the axis displays to the value
that corresponds to that position. This establishes a fixed relationship
between the actual positions of the axes and the displayed positions.
You can set 9 absolute datum points and store them in nonvolatile
memory.
Fundamentals
0
325 450 700 900 950
0
320
750
1225
300±0,1
0
150
-150
0
0
216,5
250
-250
-125
-216,5
0 -125 -216,5
-250 250
125 216,5
125
Relative
datum
Absolute
datum
Bateil1.pm6 07.11.2001, 10:36 5