NIST logo

Publication Citation: A Model for Geometry-Dependent Errors in Length Artifacts

NIST Authors in Bold

Author(s): Daniel S. Sawyer; Brian Parry; Christopher J. Blackburn; Balasubramanian Muralikrishnan; Steven D. Phillips;
Title: A Model for Geometry-Dependent Errors in Length Artifacts
Published: September 27, 2012
Abstract: We present a detailed model of dimensional changes in long length artifacts, such as step gauges and ball bars, due to bending under gravity. The comprehensive model is based on evaluation of the gauge points relative to the neutral bending surface. It yields the well-known errors observed when the gauge points are located off the center of symmetry of a bar or rod but also reveals the under appreciated, but significant, error associated with out-of-straightness of a bar or rod even if the gauge points are on the center of symmetry. For example, one experimental result shows a length change of greater than 1.5 µm on a 1 m ball bar with an out-of-straightness of 0.4 mm. This and other results are in good agreement with the model presented in this paper
Citation: Journal of Research (NIST JRES) - 117.013
Keywords: ASME B89.1.12; ball bars; Coordinate Measuring Machine (CMM); design of length artifacts; dimensional artifacts; ISO 10360, high accuracy length standards, performance evaluation of (CMM), Step Gauges
Research Areas: Dimensional Metrology, Length
DOI: http://dx.doi.org/10.6028/jres.117.013