A Model for Geometry-Dependent Errors in Length Artifacts

Published

September 27, 2012

Author(s)

Daniel S. Sawyer, Brian Parry, Christopher J. Blackburn, Balasubramanian Muralikrishnan, Steven D. Phillips

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

Report Number

117.013

NIST Pub Series

Journal of Research (NIST JRES)

Pub Type

NIST Pubs

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DOI Link

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

Citation

Sawyer, D. , Parry, B. , Blackburn, C. , Muralikrishnan, B. and Phillips, S. (2012), A Model for Geometry-Dependent Errors in Length Artifacts, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/jres.117.013 (Accessed October 7, 2025)