Calibration of gauge blocks by mechanical comparison

Project Description

To undertake a comparison of gauge blocks by mechanical comparison. The gauge blocks selected are of steel and tungsten carbide material and have nominal values as follows:

steel: 0.5 mm, 1 mm, 6 mm, 7 mm, 8 mm, 20 mm, 50 mm, 100 mm
tungsten carbide: 2 mm, 3 mm, 4 mm, 5, mm, 10 mm, 30 mm, 40 mm and 75 mm.

A single point or 5 point calibration will be undertaken on each gauge block by the measurement procedure being currently used at the project participant’s laboratory, taking into account ISO3650.
The deviation from the nominal length of each gauge block should be measured and the associated uncertainty of calibration evaluated.
The comparison will be based on the protocol used for Projects 601 and 639.


Final Report 2009-03-09

The comparison circulation started in June 2004 and ran until December 2005. Whilst no official Draft A report was issued, release of confirmed results took place just before the 2008 TC-L meeting and, with participants' permission, discussion of the data occured during the TC-L meeting in October 2008. The Draft B.1 report was prepared in September 2008. A revised Draft B.2 was issued in November 2008 and the final version of the comparison report was issued and agreed in January 2008 and submitted to the WGDM for approval in February 2008. The analysis shows no outliers and all En values are within the expected bounds. CMC claims of services taking part in this comparison are therefore supported by the results.

Further Information

To take advantage of transportation arrangements, the comparison started in June 2004 at NPL. Circulation to second participant, MSA, will be in mid July. Romania will take part later, after the gauges return to the

UK to enable a carnet or similar document to be prepared.