BS ISO BRITISHSTANDARD 261:1998 Iso general purpose metricscrewthreads- General plan ICS 21.040.10 BSi NOCOPYINGWITHOUTBSIPERMISSIONEXCEPTASPERMITTEDBYCOPYRIGHT LAW BSIS0261:1998 National foreword This British Standard reproduces verbatim IS0 261:1998 and implements it as the UK national standard. The UK participation in its preparation was entrusted by Technical Committee FME/9, Bolts, nuts and accessories, to Subcommittee FME/9/3, Reference standards for fasteners, which has the responsibility to: aid enquirerstounderstand thetext; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgatethem in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled"International Standards Correspondence Index", or by using the “Find" facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract.Users of British Standards are responsible for their correct application. Compliancewitha British Standarddoes notofitselfconferimmunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and i, the ISO title page, pages i to iv, pages 1 to 4 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. This British Standard, having been prepared under the Amendmentsissuedsincepublication direction of the Engineering Sector Committee, was Amd. No. Date Comments published under the authority of the Standards Committee and comes into effect on 15April1999 CBSI03-2000 ISBN0580323498 BS ISO 261:1998 Contents Page National foreword Inside front cover Foreword ii Text of ISO261 1 CBSI03-2000 i