The detail in designing the principal features of a vernier height gauge may vary between manufacturers. The accuracy of performance of a vernier height gauge is based upon the quality and precision of the various features, e.g. the accuracy of the dividing of the scales, the quality of the graduation marks, the straightness of the guiding edge, the flatness of the base datum and the measuring faces. These are all features which the manufacturer controls in order that measurements made with the instrument are reliable withingiven tolerances.
BS 1643:2008 specifies requirements for the construction, accuracy at the reference temperature of 20 °C and the protection of metric and imperial precision vernier height gauges which include a scriber for marking heights.
The metric height gauges measure height up to a maximum of 1 000 mm using a main scale and vernier scale graduated to read to 0.02 mm. The imperial height gauges measure height up to a maximum of 48 in using a main scale and vernier scale graduated to read to 0.001 in.
Requirements for setting blocks which might be supplied are also specified, and methods of testing height gauges are specified.
BS 1643:2008 supersedes BS 1643:1983, which is withdrawn.
