BS 1768:1963

Dimensions, general requirements for ¼ in to 2 in. Dimensions for bolts, screws, ordinary nuts, thick ordinary nuts, lock nuts, slotted nuts, thick slotted nuts. Formulae for calculation of dimensions for bolt and screw heads and nuts in intermediate or larger sizes. Applies to ferrous and non-ferrous bolts, screws, nuts and, for steel, refers to appropriate qualities up to 75 tonf/in² minimum tensile strength. Manufacturing requirements, including decarburization and rolling laps, mechanical properties and tests for steel bolts, screws, nuts. Steels suitable for various methods of manufacture are listed; testing fixtures and recommended gauges, standard sizes of bolts and screws most likely to be stocked, shortest lengths designated as bolts, identification marking.

This British Standard covers the Normal series of Unified precision hexagon bolts, screws and nuts having Unified screw threads in a range of nominal sizes from 1/4 in to 2 in inclusive. The dimensional requirements of this standard apply both to ferrous and non-ferrous bolts, screws and nuts. Mechanical properties are given only in respect of steel bolts, screws and nuts, and the finishes in which they are normally supplied are described in Clause 3.

NOTE It is considered that the range of nominal sizes included in this standard is adequate for most of the applications for which this series is likely to be employed, but for the convenience of users requiring larger sizes, the formulae from which the proportions for bolt heads and nuts are derived are given in Appendix F.