Sample Probe Files

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What does Calibration do?

MEASURE PRE-TRAVEL

All existing probes experience "pre-travel", the distance that the CNC machine travels between the time when the probe physically touches the part and the time the touch is electronically recorded at the CNC control.

Calibration is crucial for accurate dimensional measurements.

 

MEASURE REPEATABILITY

Most probes have a repeatability of less than the resolution of a machine tool. So, checking repeatability in this manner is mostly a measure of the machine tool.

However, this measurement can be used to detect other problems, such as an incorrectly or loosely mounted probe tip.

 


File Types for Probes

Several types of files are created and maintained by Metrolosys for the touch-probes used in the inspection process.

The process includes:

1) A probe definition, which describes the probe tip diameter, the set-up method, and other factors.

2) G-code is created, based on the calibration description of the number of hits, iterations (test for repeatability), and fixture offsets. (The calibration description is stored in the probe definition file.) When the g-code calibration program is run on the CNC machine then another file,

3) the result file, is created. The result file is then used to create the final probe calibration, also stored in the probe definition file.

4) A calibration report is available to show the collected data from the probe calibration.

Here are examples of a few of these file types.

G-Code for Calibration

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A standard g-code program is used to drive the probe motion around a spherical artifact.

You have the option to include the calibration motion into the main inspection program to force calibration to occur each time the inspection process is performed.

Pre-Travel Graphs

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These charts can be used to determine the distribution of the calibration probe hits, the range of pre-travel values, the repeatability of the hits, and various other statistics related to the calibration process.

When compared to previous calibration graphs, patterns and aberrations can be easily detected.