Aerospace-
UNJ threads with controlled root radius for aerospace - Inch series
British Standard Committeesresponsibleforthis
ACE/12Aerospacefasteners and fastening systemsupon whichthe followingbodies were represented:
Association of Electronic Telemunications and Business Equipment IndustriesBritish Industrial Fasteners FederationSoclety of Brtish Aerospace Companies Ministry of Defence
This British Standard having direction of the Engineering been prepared under theSector Board was publshed under the authority of theStandards Board and coemes into effect on15 August 1996
Amendments issued since publication
BST 1996
Arad No. Date Text affected
Pirst published December 1978 Second editon August 1996
The following BSI referencesComsttee refereoe:ACE/12 standard: relate to the work on thisDraf for ment 92/80212 DC
ISBN 0 580 26147 6
Contents
Specification1 Scope Definition 12 Symbols 1 14 Series of threads Basic profile of thread 15 6 Tolerances 3 27 Designation of threads Gauging by limit gauges 99 8 Tables 6 7
Tables
Basic profile1 2 Basic dimensions 9 83 spas pean 124 Values of tolerances for profile dimensions Limit values of the root radlus R 14 156 Maximum pemissible variation in the lead variation and half-angle 267 Basic profle data foruse in calculation of special diameter/pitch binations 338 Pitch dinmeter tolerances for extemal threads of spectal dlameter/pitch binations (UNJS threads)Pitch diameter tolerances for intemal thrends of special diameter/pitch 3410 Minor diameter tolerances for mtemal threads of special diameterpitch 35binations (UNJS threads) 36
Figures
1 Basic profile 2Length of engagement Intemal thread tolerances 33 4 Extermal thread tolerances 3 45 Rardius at the root of the screw thread 5
Nationalforeword
sforaerospaoenhserio publihod by theIntemationalOrganization for Standardization (ISO). It supersedes BS 4084 : 1978 which Is withdrawn.
Compliance with a British Standard does not ofitself confer immunityfrom legal obligations.
Aerospace-UNJthreads withcontrolledrootradius for aerospace-Inchseries
1Scope
2 Definition
3Symbols
This international Standerd specifies the character- istics of inch series UNJ threads with controlied rootradius.
It determines thebasic trianguler profile for this type of thread and gives a system for designating the di-ameter/pithbinationsForalldiameters0o60in to 6 000 in it offers in the form of tables the basic dimensions and tolerances for a selection of diam-of calculation for the dimensions and tolerances for eter/pitch binations.it elso provides the methodtables including threads with a diameter in excess of any diameter/pitch bination not given in the6 000 in.
relating toImit gaugesreferred toin the footnotein NOTE 1Pending publication ot the International Standardclause 7 speciat care must be taken to ensure that the dimensions and tolerances specified in this InternationalStandard are confirmed by alternative means.
This International Standard applies primarily to the threads of inch series aerospace fasteners.
For the purposes of this Internetional Standard， thefollowing definition applies.
2.1basic profile: The theoretical profile correspond- ing to the basic dimensions i.e. the major diameter the pitch diameter and the minor diameter. Seefigure 1 and clause 3.
The tolerances are applied to the basic profile.
D= basic major diameter of internal threadD2 = basic pitch diemeter of internal thread
D = besic minor diemeter of internal threadd=basic major dlameter of external threadd-besicminor diameter of external thread d2 = basic pitch diameter of external threadH= height of fundamental triangleP=pitchn= number of threads per inch
4Basic profile of thread
4.1 Baslc profile dimensions
Values given in table 1 have been calculated according to the following formulae:
4.2 Basic dimensions of thread
Values given in table 2 have been calculated accordingto the following formulae:
