BS 1768:1963

Co-operating organizations
Foreword
1 Scope
2 Material and manufacture
3 Finish
4 Mechanical properties of steel bolts and screws
5 Tensile strength and proof stress of bolts and
   screws
6 Grading and mechanical properties of steel nuts
7 Proof load for nuts
8 Dimensions
9 Length of bolts and screws
10 Ends of bolts and screws
11 Screw threads
12 Length of thread
13 Nuts, squareness of thread to face
14 Chamfering, washer facing and countersinking
15 Split-pin holes and slots
16 Marking
17 Inspection and testing
Appendix A - Mechanical properties of finished steel
             hexagon head bolts and screws and hexagon
             nuts
Appendix B - Materials
Appendix C - Testing fixtures and recommended gauges
Appendix D - Standard sizes of Unified precision steel
             hexagon head bolts and screws and shortest
             lengths designated as bolts
Appendix E - Details of identification marking for
             Unified hexagon bolts, screws and nuts
Appendix F - Formulae

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.