Properties of free-standing ball bar systems

Abstract This article offers recommendations to coordinate-measuring machine (CMM) buyers, sellers, and users on the design of free-standing ball bar systems used to evaluate the volumetric performance of CMMs according to the ANSI/ASME B89.1.12M standard. These systems are more widely used today than earlier methods such as magnetic ball bars. In this article we study the general design requirements, mechanical deformations under gravity and probing forces, vibrational considerations, and thermal effects on free-standing ball bar systems. We conclude with a summary of the issues in ball bar design, which must be considered in order to maintain an artifact error budget of ∼1 μm.