Concentricity*
Concentricity requires a single datum to be defined. The measurements of the datum are first aligned to this datum and then the measurements of the check feature are evaluated relative to this datum by establishing a median point for each cross section and comparing its position relative to the axis of the datum feature.
Evaluation Process within SA:
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The measurements of the datum are aligned to the datum feature which orients the nominal feature and the measurements of it.
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The actual feature type is established (circle or cylinder) based on the nominal type (feature to which the annotation is attached) and fit to the entire data set to establish the direction vector for this measured feature.
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Cross sections are established along this direction vector and the data is divided into groups based upon the distance of each point along this direction vector and the cross section width definition.
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The data in each cross section is evaluated independently. A circle is fit to the data in each group using the datum direction axis and the center or “medial” point established.
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The distance of each median point from the datum axis is used for the evaluation.