Understanding the importance of collecting accurate data, using the correct drift checks, and applying accurate thermal scaling are critical elements of a successful measurement plan. Even if all the correct measurement techniques are applied, creating the coordinate system incorrectly will generate inaccurate inspection data.

When parts are manufactured on a machine tool, the datum or reference-feature orientations are inherent to the machining process. The machine table, angle plates, indexing rotary, and parallel blocks all control the orientation and alignment of the part throughout the machining process. Laser trackers, portable coordinate measuring machines (CMMs), or scanners develop a digitized model of X, Y, and Z point clouds or discrete points. From these data points it’s possible to create features such as circles, planes, lines, or surfaces. During the analysis process, it can be determined what features or points will control the six degrees of freedom. These points will determine the location and orientation of the coordinate system to best support the drawing and design intent.

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