Final report on EURAMET.L-S21: `Supplementary comparison of parallel thread gauges'

The results of the comparison of parallel thread gauges between ten European countries are presented. Three thread plugs and three thread rings were calibrated in one loop. Croatian National Laboratory for Length(HMI/FSB-LPMD) acted as the coordinator and pilot laboratory of the comparison. Thread angle, thread pitch, simple pitch diameter and pitch diameter were measured. Pitch diameters were calibrated within 1a, 2a, 1b and 2b calibration categories in accordance with the EURAMET cg-10 calibration guide. A good agreement between the measurement results and differences due to different calibration categories are analysed in this paper. This comparison was a first EURAMET comparison of parallel thread gauges based on the EURAMET cg-10 calibration guide, and has made a step towards the harmonization of future comparisons with the registration of CMC values for thread gauges.