RESULTS OF THE NIST NATIONAL BALL PLATE ROUND-ROBIN

This report examines the results of the ball plate round robin adminis tered by NIST. The round robin was part of an effort to assess the cur rent state of industry practices for measurements made using coordinat e measuring machines. Measurements of a two-dimensional ball plate (24 0 mm by 240 mm) on 41 coordinate measuring machines were collected and analyzed. Typically, the deviations of the reported X and Y coordinat es from the calibrated values were within +/- 5 mu m, with some coordi nate deviations exceeding 20.0 mu m. One of the most significant obser vations from these data was that over 75 % of the participants failed to correctly estimate their measurement error on one or more of the ba ll plate spheres.