Establishing a Reference Frame While a reference frame might be unnecessary for quick checks of part features in prototyping or similar environments, a reliable measurement reference must be established prior to a formal manufacturing inspection process or program playback. The M2 measurement reference frame consists of: • Skew alignment (secondary alignment) • Part Datum (measurement coordinate system origin) Skew alignment When a part is misaligned (twisted) in the XY plane, small cosine errors can be generated during the measurement process. These errors can be eliminated by creating a skew alignment for the part. The skew alignment performs a precise measurement of the part misalignment in the XY plane. Once the misalignment is known to the system, subsequent feature measurements are automatically compensated to eliminate cosine errors. Measurement data in the Feature Detail and DRO screens will reflect measurements of a perfectly aligned part. To create a skew alignment: 1 Select the desired probe from the probe menu. Measure toolbar > Probe menu > Desired probe 2 Press the Skew button of the Datum menu. Measure toolbar > Datum menu > Skew button
3 Probe a minimum of two points well distributed along the entire length of the desired part reference edge.
NOTE The skew alignment is of fundamental importance to subsequent feature measurements. Probing more points on the reference edge will increase measurement accuracy.
4 Press the Done button to complete the measurement and enter the skew line into the Feature List. Measure toolbar > Done button Part Datum Creating the part datum point is the final step in establishing a valid reference frame. The part datum can be created by: • Probing a single point • Constructing a point from one or more parent features • Manually zeroing the X and Y position coefficients of a feature Probing a Part Datum Point The part datum can be created directly by probing a point. To probe a part datum point: 1 Select the desired crosshair probe from the probe menu. Measure toolbar > Probe menu > Simple or optical edge crosshair probe 2 Press the Datum button. Measure toolbar > Datum button 3 Probe the desired data point as described earlier. 4 Press the Done button to complete the measurement and enter the part datum point into the Feature List. Measure toolbar > Done button
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