SIM.4.2 Regional Comparison Stage Two: Calibration of gauge blocks by mechanical comparison

Results of the Stage Two portion of the Inter-American System of Metrology (SIM) regional international comparison of gauge block calibration by mechanical comparison are presented. This measurement round-robin employed the same short gauge blocks that were used in Stage One, measurement by optical interferometry. The gauge blocks, six made of steel and six made of tungsten carbide, ranging in nominal length from 2 mm to 100 mm, were calibrated by nine national metrology institutes of the SIM region. Laboratories used various techniques to establish traceability to the definition of the metre. Results of central length calibration are presented and discussed with regard to traceability, temperature control, mechanical calibration employing dissimilar materials, and the relationship with Stage One of the comparison. Measurement uncertainty evaluation is also discussed.