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Touch Probe “Pre-Travel” stylus diameter calibration procedure.
Calibrate the probe stylus diameter for the tool library. Just entering the value of the probe tip diameter in the tool library
will not produce accurate results unless they are corrected for stylus pre-travel.
Pre-travel is the amount of deflection of the stylus tip before the probe detects the surface. This value varies depending
on the length of the stylus and the speed and direction that the stylus tip is moving when it makes contact with the surface
being probed or digitized. Pre-travel variation amount should be stated in probe specifications relative to stylus length and
direction of travel limitations. A probe that has small pre-travel variation with no restriction on stylus length and direction
of travel will be quite expensive. Machine characteristics including lash and input latency also contribute to the need to
calibrate the stylus diameter. Each stylus has its own
Stylus diameter calibration procedure.
1.) Fixture a precision ring gauge on the machine tool. The ring must lie flat on the work table/vise with the center line of
the bore aligned with the center line of the probe stylus/spindle. Make sure the probe is plugged in and working and test
before use! Go to the Tool Library Offset menu and set the diameter for the Probe Tool Number to 0.0000 in our case Tool
10 is the Probe Tool number so we set Diameter 10 to 0.0000
2.) Jog the probe over the center (roughly) of the ring gauge, and then slowly jog the Z-axis down until the tip of the probe
is inside the bore and not touching anything.
3.) From the main screen of CNC12, press <F1-Setup>, then <F1-part>, then <F5-Probing>, then <F1-Bore>,and finally
<Cycle Start>. The control will jog the stylus to and probe each quadrant of the bore. It will then return to the center of the
bore. The message box will appear on the screen displaying the measured bore diameter.
