BS 817:2008

• 17.040.30 Measuring instruments

This British Standard specifies the construction, and dimensions and tolerances, for rectangular and square surface plates for use as working planes for engineering purposes, made of cast iron or granite, in two size ranges, from 160 mm × 100 mm to 2 500 mm ×1 600 mm and from 12 in × 12 in to 96 in× 48 in, and in four grades of accuracy.

The standard is applicable to new surface plates and to plates that are being resurfaced after they have become worn.

In addition to the definitive requirements, this standard also requires the items detailed in Clause 4 to be documented. For compliance with this standard, both the definitive requirements and the documented items have to be met.

NOTE 1 The inch sizes are given as this information is still required by industry. Attention is drawn to the fact that metric dimensions are not necessarily direct conversions of the imperial dimensions.

NOTE 2 General information on the care and use of surface plates is given in Annex A.