BRITISHSTANDARD
Part3:Screwthreadswithdiameters belowin-Requirements
ICS 21.040.20
NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW
Publishing and copyright information
BSI 2007
ISBN 978 0 580 57927 1
Publication history
First published August 1965Second edition December 2007
The BSI copyright notice displayed in this document indicates when the document was last issued.
The following BSI references relate to the work on this standard:Draft for ment 07/ DC Committee reference FME/9
Text affeeted
Contents
Foreword iii
Annexes
Bibliography 17
List of tables
1 Scope12 Normative references 13 4 Terms and definitions and symbols 1 Thread profiles 15 Diameter/pitch binations 29 7 Tolerances allowances and limits of size for uncoated threads 2 Tolerance classes 28 9 Coated threads 3 Designation of threads 410 Gauges 4
attachment purposes and for general use in the aircraft industry 16 Annex A (normative) Unified screw threads below ↓ in diameter for
Table 1 Unified screw threads below ↓ in diameter standard series 5Table 2 Unified screw threads below ↓ in diameter standard series Table 3 Coarse thread series (UNC) below ↓ in diameter Limits of size 6Limits and tolerances for finished uncoated threads External threadsTable 4 Coarse thread series (UNC) below ↓ in diameter Class 2A 8Limits and tolerances for finished uncoated threads Internal threadsTable 5 Coarse thread series (UNC) below ↓ in diameter - Class 2B 8Limits and tolerances for finished uncoated threads External threadsTable 6 Coarse thread series (UNC) below ↓ in diameter Limits and Class 3A 9tolerances for finished uncoated threads Internal threads Class 3B 9Limits and tolerances for finished uncoated threads External threads Table 7 Fine thread series (UNF) below ↓ in diameter Class 2A 10Table 8 Fine thread series (UNF) below ↓ in diameter Limits and tolerances for finished uncoated threads Internal threadsClass 2B 10Table 9 Fine thread series (UNF) below ↓ in diameter Limits and tolerances for finished uncoated threads External threadsClass 3A 11Limits and tolerances for finished uncoated threads Internal threads Table 10 Fine thread series (UNF) below ↓ in diameter -Table 11 Extra fine thread series (UNEF) below ↓ in diameter Class 3B 11Limits and tolerances for finished uncoated threads External threadsTable 12 Extra fine thread series (UNEF) below ↓ in diameter Classes 2A and 3A 12Limits and tolerances for finished uncoated threads Internal threadsTable 13 Coarse thread series (UNC) sizes below ↓ in diameter Classes 2B and 3B 12Basic dimensions 13
Table 14 Fine thread series (UNF) sizes below ↓ in diameter Basic dimensions13 Table 15 Extra fine thread series (UNEF) sizes below ↓ in diameter Basic dimensions14Table 16 Thread data for unified thread form 24 t.p.i. to 80 t.p.i. 15
Foreword
Publishing information
Supersession
Relationshipwith otherpublications
BS 1580 is now published in two parts
Hazard warnings
Presentationalconventions
Contractual andlegalconsiderations
This part of BS 1580 is published by BSI and came into effecton 31 December 2007. It was prepared by Submittee SFTSE/1 Screus and fasteners technical specification mittee under the authority of Technical Committee FME/9 Nuts bolts and accessories.A list of organizations represented on this mittee can be obtainedon request to its secretary.
This part of BS 1580 supersedes BS 1580-3:1965 which is withdrawn.
Part 1: Screw threads with diameters ↓ in and larger -Part 3: Screw threads with diameters below in RequirementsRequirements
This part of BS 1580 is intended for use with BS 919-1 which specifiesthe corresponding screw gauges.
This part of BS 1580 has been fully revised to bring it up to date.
The range of diameters covered by this part of BS 1580 falls within therange of the B.A. screw thread sizes given in BS 93. The various pitcheswider selection of diameter/pitch binations for specific applications given for the same diameter in the unified system however offer athan do those in the B.A. system. The UNF series gives the closestapproximation to the B.A. diameter/pitch binations.
WARNING. Attention is drawn to the fact that with the differentscrew thread forms available there is the possibility of a mismatch which is potentially hazardous. It is the responsibility of the designerof the end product to ensure that this possibility is reduced to aminimum. For further information on mismatches of screw thread systems see PD 6494.
The provisions of this standard are presented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principalauxiliary verb is “shall".
presented in smaller italic type and does not stitute a Commentary explanation and general informative material isnormative element.
This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.
Compliance with a British Standard cannot confer immunityfrom legal obligations.
