HEIDENHAIN TNC 128 (77184x-01) - Manual (Page 304)

304 Manual operation and setup
1
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Circle center as datum
With this function, you can set the datum at the center of bore holes,
circular pockets, cylinders, studs, circular islands, etc.
Inside circle:
The TNC probes the inside wall of a circle in all four coordinate axis
directions.
For incomplete circles (circular arcs) you can choose the appropriate
probing direction.
 Position the touch probe approximately in the center of the circle
 Select the probing function: Press the PROBING CC
soft key
 Select the probing direction or press the soft key for
the automatic probing routine
 Start the probing procedure: Press the machine
START button. The touch probe probes the inside
wall of the circle in the selected direction. If you are
not using the automatic probing routine, you need to
repeat this procedure. After the third probing
operation, you can have the TNC calculate the center
(four touch points are recommended).
 Terminate the probing procedure and switch to the
evaluation menu: Press the EVALUATE soft key
 Datum : In the menu window, enter both coordinates of
the circle center, confirm with the SET DATUM soft
key, or write the values to a table (see "Writing the
measured values from touch probe cycles to datum
tables", page 295, or see "Writing the measured
values from touch probe cycles to the preset table",
page 296)
 Terminate the probing function: Press the END soft
key
X
Y
X+ X–
Y+
Y–
X
Y
X+
X–
Y+
Y–
The TNC needs only three touch points to calculate
outside or inside circles, e.g. for circle segments. More
precise results are obtained if you measure circles using
four touch points, however. You should always
preposition the touch probe in the center, or as close to
the center as possible.