HEIDENHAIN TNC 640 (34059x-04) ISO programming - Manual (Page 475)

Datum setting without a 3-D touch probe 15.5
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TNC 640 | User's Manual for DIN/ISO Programming | 3/2014
475
15.5 Datum setting without a 3-D touch
probe
Note
Setting the datum with a 3-D touch probe: See
"Datum Setting with 3-D Touch Probe ", page 498.
You fix a datum by setting the TNC position display to the
coordinates of a known position on the workpiece.
Preparation
Clamp and align the workpiece
Insert the zero tool with known radius into the spindle
Ensure that the TNC is showing the actual position values
Workpiece presetting with axis keys
Protective measure
If the workpiece surface must not be scratched, you
can lay a metal shim of known thickness d on it.
Then enter a tool axis datum value that is larger than
the desired datum by the value d.
Select the MANUAL OPERATION mode
Move the tool slowly until it touches (scratches)
the workpiece surface
Z
Select the axis
DATUM SETTING Z=
Zero tool, spindle axis: Set the display to a known
workpiece position (here, 0) or enter the thickness
d of the shim. In the machining plane: Take the
tool radius into account
Repeat the process for the remaining axes.
If you are using a preset tool, set the display of the tool axis to the
length L of the tool or enter the sum Z=L+d
The TNC automatically saves the datum set with the
axis keys in line 0 of the preset table.