NTERNATIONAL STANDARD Tso 839/ II Milling machine arbors with 7/24 tapers - Part II : Accessories Arbresporte-fraisesaucone7/24-Partiell:Equipements First edition-1977-08-01 SO 839/11-1977 (E) UDC621.914.3-229.2 Ref.No.ISO 839/lI-1977 (E) Descriptors : tools, machine tools,milling cutter arbors, accessories, spacers, bearing collars, locknuts, dimensions. Price based on 5 pages FOREWORD ISO (the International Organization for Standardization) is a worldwide federation of national standards institutes (isO member bodies). The work of developing International Standards is carried out through Iso technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with IsO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International StandardsbytheISOCouncil. Committee International StandardISO839/Il was developed by Technical ISO/TC 29, Small tools, and was circulated to themember bodies in April 1976. It has been approved by the member bodies of the following countries : India Romania Australia Austria Israel South Africa, Rep. of Belgium Italy Spain Czechoslovakia ueder Switzerland France Korea, Rep. of Turkey Germany Mexico United Kingdom Hungary Poland U.S.S.R. Nomemberbody expressed disapproval of thedocument This International Standard cancels and replaces sub-clauses 3.2 and 4.2 of ISO Recommendation R 839-1968, of which it constitutes a technical revision. InternationalOrganizationforStandardization,1977 Printed in Switzerland ISO839/II-1977 (E) INTERNATIONALSTANDARD Milling machine arbors with 7/24 tapers Part Il : Accessories 0 INTRODUCTION REFERENCES 2 During the prepatory work on ISO/R839-1968,it was IsO240,Milling cutters -Interchangeability dimensions found that it was impossible to unify milling machine for cutter arbors or cutter mandrels -Metric series and arbors and their accessories in a manner which would be inch series. satisfactory to countries using the metric system and to ISo/R272,Hexagonbolts and nuts-Widthsacross flats, those using the inch system. The iSO Recommendation heights of heads, thicknesses of nuts -Metric series. therefore standardized two completely distinct series of accessories. There was thus no interchangeability between ISO 297,7/24 tapers for toolshanks. these two series, based respectively on the metric and the inch series of ISO 240. iso839/l,Millingmachinearborswith 7/24tapers Part I : Dimensions. This International Standard retains metric series only, this series being regarded as the only one recommended for the future. Nevertheless, the inch series is given in an annex. CHOICEOFDIMENSIONS 3 The dimensions retained are those corresponding to the most commonly used diameters of milling machine arbors, i.e.thevaluesof IS0240from16to100mm(omitting 19 mm and 70 mm). SCOPEANDFIELDOFAPPLICATION Bearing collars are specified only for arbors with useful lengths I greater than 160 mm, as shorter arbors are usually This International Standard specifies the recommended intended for work which does not entail mounting on the manufacturing dimensions for milling machine accessories : machine with a steady (working in air) or, as a resuit, the spacing collars, bearing collars and clamping nuts. use of a bearing collar. Milling machine arbors with 7/24 tapers are specified NOTE -This International Standard will be supplemented further inISO839/1. 1