BS 1580-1:2007

Foreword
Section 1: General
1 Scope
2 Normative references
3 Terms and definitions and symbols
4 Profile of unified screw threads
Section 2: Standard series
5 Diameter/pitch combinations
6 Tolerance classes of external and internal threads
7 Limits of size, and tolerances, for uncoated threads
8 Allowances for uncoated threads
9 Coated threads
10 Gauges
11 Designation of unified screw threads
Section 3: Special series (UNS)
12 Diameter/pitch combinations, fractional sizes
13 Diameter/pitch combinations, decimal sizes
14 Tolerance classes of external and internal UNS threads
15 Tolerances and allowances
16 Coated UNS threads
17 Designation of UNS threads
Annexes
Annex A (informative) - Bases of tolerances and allowances
        for unified screw threads [1/4] in and larger
Annex B (informative) - Outline guide, and examples, for
        calculating limits of size of untabulated UNS screw
        threads
Annex C (informative) - Forms of the crest of external threads
Annex D (informative) - General symbols
Annex E (informative) - Tolerances on pitch and flank angle in
        relation to tolerance on effective diameter
Annex F (informative) - Standard unified thread series,
        guidance on selection and use
Annex G (informative) - Standard unified thread series,
        information and guidance regarding the tolerance
        classes
Bibliography

Defines limits of sizes, and tolerances, for single-start, clearance-fit unified screw threads, in inch units, with nominal diameters [1/4] in and above, having the ISO basic profile as specified in BS ISO 68-2:1998.

This part of BS1580 specifies limits of sizes, and tolerances, for single-start, clearance-fit unified screw threads, in inch units, with nominal diameters in and above, having the ISO basic profile as specified in BSISO68‑2:1998. The part of BS1580 specifies the following unified thread series as follows: standard variable pitch series: a coarse thread series (UNC) from in to 4 in nominal diameter; a fine thread series (UNF) from in to in nominal diameter; an extra fine thread series (UNEF) from in to in nominal diameter; standard constant pitch series: a 4-threads per inch series (4 UN) from in to 6 in nominal diameter; a 6-threads per inch series (6 UN) from in to 6 in nominal diameter; an 8-threads per inch series (8 UN) from in to 6 in nominal diameter; a 12-threads per inch series (12 UN) from in to 6 in nominal diameter; a 16-threads per inch series (16 UN) from in to 6 in nominal diameter; a 20-threads per inch series (20 UN) from in to 3 in nominal diameter; a 28-threads per inch series (28 UN) from in to in nominal diameter; a 32-threads per inch series (32 UN) from in to 1 in nominal diameter; a special thread series (UNS) with diameter/pitch combinations other than those specified for the standard series. NOTE1 A transition fit series and an interference fit series of UNC and UNF threads for application to screwed studs are given in BS2693‑1 and -2, respectively. NOTE2 Bases of tolerances and allowances are given in Annex A, guidance for calculating limits of size is given in Annex B, information on crest forms of external threads is given in Annex C, some general symbols are given in Annex D (see 3.2), information on tolerances is given in Annex E, guidance on selection and use of the standard unified thread series is given in Annex F and information and guidance on tolerance classes is given in Annex G.