Virtual spheres gauge for coordinate measuring arms performance test

This work presents a new class of gauges with virtual spheres to check the performance of coordinate measuring arms (CMA). The proposed gauge has two groups of four holes that are used to determine points of two spherical surfaces. These points are fitted to spheres using computational algorithms and the distance between the center of the spheres is calculated. The proposed gauge was named virtual ball bar and an application was performed to test the performance of an articulated arm CMA with rigid probe. The results were compared with the application of the ANSI/ASME B89 volumetric performance test using a conventional ball bar and the proposed virtual ball bar. An additional experiment using fractional factorial design was carried out to complement the comparison of the gauges. The results showed good agreement between the two approaches and it was observed a potential cost reduction compared to ball bar gauge.