Roundness measurements are of major importance in many aspects of industry and science. It is therefore essential to ascertain the traceability to standards and to have a sound knowledge of the capabilities of facilities which aim to achieve the highest accuracy level. An independent proof of the traceability and consistency of measurement methods is most effectively given by an international comparison. Within the European community, two intercomparisons have been carried out in the framework of the EC Measurements and Testing programme. In the first intercomparison of roundness standard calibrations the agreement among the National Metrology Institutes was not fully satisfactory. Since then, a number of laboratories have improved their equipment and procedure. In a second inter comparison 8 laboratories participated which all were able to separate the spindle deviations from the component profile. Because of the encouraging results of this second inter comparison, 5 Euromet members decided to compare in detail the profiles of one of the artifacts used, outside the scope of the EC Measurement and testing programme.
The latter comparison, in which various data analysis techniques will be used to derive conclusions about the consistency of the measured profiles, is carried out in the framework of this Euromet project.