A comparison of measurement variations for selected probe head configurations for coordinate measuring machines

In coordinate measuring machine (CMM) research, there is often a need to measure the same feature repeatedly using multiple settings. However, the effects of changing the probe head configuration was previously unknown. The goal of this research was the determination of what effects the selection of the measurement plane, adaptor style, stylus length, and stylus size would have on the CMM's ability to repeatedly measure a single diameter.; An analysis of variance (ANOVA) study was conducted using the Brown & Sharpe MicroVal CMM at Indiana State University (ISU). Three measurement planes (XY, XZ, and YZ), two adaptor styles (a star probe and an indexable head), two stylus lengths, and two stylus sizes were selected for the study. Ten measurements were taken on a single gage ring for each variable combination and the data were processed in SPSS.; The results of this study indicate that if the measurement plane, stylus length, or stylus size were changed, the CMM would not repeatedly result in the same measurement reading. However, the user would be able to alter the adaptor style without affecting the resulting measurement. Additionally, the interactions of (a) measurement plane and adaptor style; (b) measurement plane and stylus length; (c) measurement plane, adaptor style and stylus length; (d) measurement plane, adaptor style and stylus size; and (e) measurement plane, adaptor style, stylus length, and stylus size all show significant measurement variations for the same feature. As future research is done on CMMs, care will be needed with the assumptions that are made when researching a specific effect. Based on this study, future researchers will have to determine whether observed changes are due to the probe head configuration or the changes they are studying.