BS 817:2008

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Information to be supplied and items to be agreed
5 Classification
6 Materials
7 Construction
8 Finish
9 Rigidity of surface plates of 400 mm x 250 mm or 12 in. x 12 in.,
   and larger
10 Accuracy
11 Cover and other protection
12 Marking
Annexes
Annex A (informative) - Recommendations on the care and use of
                        surface plates
Annex B (normative) - Test for rigidity of surface plates
Annex C (informative) - Assessment of bearing area of cast iron
                        surface plates
Annex D (informative) - Calculation of permitted deviation from
                        flatness of the working surface
Bibliography

Describes 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 x 100 mm to 2500 mm x 1600 mm and from 12 in. x 12 in. to 96 in. x 48 in., and in four grades of accuracy.

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 160mm×100mm to 2500mm×1600mm and from 12in×12in to 96in×48in, 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 Clause4 to be documented. For compliance with this standard, both the definitive requirements and the documented items have to be met.

NOTE1 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.

NOTE2 General information on the care and use of surface plates is given in AnnexA.