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3-16

LP2 probe system: System installation

Calibrating the LP2

Why calibrate a probe?

A spindle probe is just one component of the measurement system which communicates with the machine

tool. Each part of the system can introduce a constant difference between the position that the stylus

touches and the position that is reported to the machine. If the probe is not calibrated, this difference will

appear as an inaccuracy in the measurement. Calibration of the probe allows the probing software to

compensate for this difference.

During normal use, the difference between the touch position and the reported position does not change,

but it is important that the probe is calibrated in the following circumstances:

• when a probe system is to be used for the rst time;

• when the LP2 operating conguration is changed;

• when a new stylus is tted to the probe;

• when it is suspected that the stylus has become distorted or that the probe has been crashed;

• at regular intervals to compensate for mechanical changes of your machine tool;

• if repeatability of relocation of the probe shank is poor. In this case, the probe may need to be

recalibrated each time it is selected.

Three different operations are to be used when calibrating a probe. They are:

• calibrating either in a bored hole or on a turned diameter of known position;

• calibrating either in a ring gauge or on a datum sphere;

• calibrating the probe length.

Calibrating in a bored hole or on a turned diameter

Calibrating a probe, either in a bored hole or on a turned diameter of known size, automatically stores

values for the offset of the stylus ball to the spindle centre line. The stored values are then used

automatically in the measuring cycles. Measured values are compensated by these values so that they are

relative to the true spindle centre line.

Calibrating in a ring gauge or on a datum sphere

Calibrating a probe either in a ring gauge or on a datum sphere with a known diameter automatically

stores one or more values for the radius of the stylus ball. The stored values are then used automatically

by the measuring cycles to give the true size of the feature. The values are also used to give true positions

of single surface features.

NOTE: The stored radius values are based on the true electronic trigger points. These values are different

from the physical sizes.

Renishaw LP2 Installation Guide

Other manuals for Renishaw LP2