BS 1580-1 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 BS ISO 68-2:1998.
BS 1580-1specifies the following unified thread series as follows:
a) standard variable pitch series:
- a coarse thread series (UNC) from 1/4 in to 4 in nominal diameter
- a fine thread series (UNF) from 1/4 in to 1 1/2 in nominal diameter
- an extra fine thread series (UNEF) from 1/4 in to 1 1/16 in nominal diameter
b) standard constant pitch series:
- a 4-threads per inch series (4 UN) from 2 5/8 in to 6 in nominal diameter
- a 6-threads per inch series (6 UN) from 1 7/16 in to 6 in nominal diameter
- an 8-threads per inch series (8 UN) from 1 1/16 in to 6 in nominal diameter
- a 12-threads per inch series (12 UN) from 5/8 in to 6 in nominal diameter
- a 16-threads per inch series (16 UN) from 7/16 in to 6 in nominal diameter
- a 20-threads per inch series (20 UN) from 5/16 in to 3 in nominal diameter
- a 28-threads per inch series (28 UN) from 5/16 in to 1 1/2 in nominal diameter
- a 32-threads per inch series (32 UN) from 7/16 in to 1 in nominal diameter
c) a special thread series (UNS) with diameter/pitch combinations other than those specified for the standard series.
BS 1580-1 is intended for use with BS 919-1 and BS 919-4 which specify the corresponding screw gauges.
BS 1580-1 contains:
Section 1: General
Scope
Normative references
Terms and definitions and symbols
Profile of unified screw threads
Section 2: Standard series
Diameter/pitch combinations 9
Tolerance classes of external and internal threads
Limits of size, and tolerances, for uncoated threads
Allowances for uncoated threads
Coated threads
Gauges
Designation of unified screw threads
Section 3: Special series (UNS)
Diameter/pitch combinations, fractional sizes
Diameter/pitch combinations, decimal sizes
Tolerance classes of external and internal UNS threads
Tolerances and allowances
Coated UNS threads
Designation of UNS threads
BS 1580-1:2007 supersedes BS 1580: Parts 1 & 2:1962, which is withdrawn.
