Bilateral comparison of squareness measurements

Project Description

In the frame of EUROMET #570 corrective actions, GUM has reconstructed its standard equipment for the calibration of big squares.

This bilateral comparison is aimed to test the parameters of the new measurement setup and to confirm the related uncertainty values claimed in the GUM length CMC tables. The comparison will proceed according to the Protocol for the EUROMET #570, adapted for one cylindrical artifact (similar to that one used in #570).


cylindrical squareness standard of steel with 102 mm diameter and 401,5 mm height with marked positions for the profile lines, weight 25 kg.

The following parameters have to be calibrated:

interior angles γ0, γ90, γ180, γ270 between the LS regression-line fitted through the measurement profiles at 0°, 90°, 180°, 270° and the envelope plane of the basis (resting on a surface plate),
local LS straightness deviation for all measured profiles of both standards (results had to be reported in electronic format only).

For all reported results, an uncertainty budget and the combined standard uncertainty uC, evaluated according to ISO-guide to the expression of uncertainty of measurement, has to be given.

Final Report 2011-08-23

The comparison has been completed and the results are available in the KCDB.

Further Information

[Jul 06]For the sake of information exchange, covering the dimensional metrology, the participation of two SMU experts is suggested.

Length (L)
Jiri Mokros, SMU (Slovakia)
Phone: +421 2 60294 253
Fax: +421 2 65429 592
Coordinating Institute
SMU (Slovakia)
Participating Partners
GUM (Poland)