HEIDENHAIN TNC 620 Programming Station, User Manual, Page: 535 / 695

Datum setting with a 3-D touch probe (option number 17) 14.10
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HEIDENHAIN | TNC 620 | ISO Programming User's Manual | 9/2016
535
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 touch probe function: Press the
PROBING CC
soft key
Select the soft key for the desired probing
direction
Probe: Press the
NC START
key. The touch probe
probes the inside wall of the circle in the selected
direction. Repeat this process. 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
Further Information: "Writing measured values
from the touch probe cycles to a datum table",
page 519
Further Information: "Writing measured values
from the touch probe cycles to the preset table",
page 520
To terminate the probe function, press the
END
soft key
The TNC needs only three touch points to calculate
outside or inside circles, e.g. with 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.