Resetting The Machine Datum - HEIDENHAIN iTNC 530 Service Manual

18.1.8 Resetting the machine datum

As the machine datum (machine reference) refers to the positon encoder datums, it may be
necessary to reset it after removing and mounting scales, scale tapes, scanning heads or angle
encoders.
Individual axis
18 – 288
Note
On simple 3-axis machines, it is often not required to reset the machine datum. It is
sufficient to the check the software limit-switches and to reset them, if necessary. If you
have any questions, contact your machine tool builder!
Caution
Setting the machine datum is absolutely essential on most machine tools with 5-axis
machining and with tool changers.
If the NC programs are written with relation to the machine datum, it needs to be exactly
determined again.
Note
The OEM may have defined the machine datum beyond the range accessible by the
machine axes, i.e. it cannot be approached.
In such a case the OEM will specify a fixed point (reference hole or stud, etc.) in the
machine's work envelope with an offset to the machine datum (e.g. 500 mm).
Note
The OEMs frequently provide instructions for setting the machine datum. Sometimes the
axis compensations and kinematics settings need to be deactivated before you can reset
the machine datum, but have to be reactivated and reset afterwards.
Thus consult the machine manufacturer!
The following descriptions are only possibilities.
Always try to mount the encoder as exactly as possible to its original position!
Set the display to REF. --> Now you can see the current actual position of the axis
referenced to the machine datum.
Set the position display step in MP 7290.x to the highest resolution.
Note
Sometimes the axis compensations and kinematics settings need to be deactivated before
you can reset the machine datum. --> Ask the machine manufacturer.
Reference the axis concerned.
Position the machine datum or a machine's reference point defined by the machine
manufacturer (e.g., table edge and surface, ring in the middle of the rotary table, reference
hole, reference stud, etc.).
Note
If you traverse the reference mark, equate the ACTL values with the REF values (set datum).
HEIDENHAIN Service Manual iTNC 530