ISO 866-1975 pdf free.Centre drills for centre holes without protecting chamfers—Type A.
ISO (the lnternational Organization for Standardization) is a worldwide federationof national standards institutes (ISO Member Bodies). The work of developingInternational Standards is carried out through lSO Technical Committees. EveryMember Body interested in a subject for which a Technical Committee has been setup has the right to be represented on that Committee.International organizations,governmental and non-governmental, in liaison with lSO, also take part in the work.
Draft International Standards adopted by the Technical Committees are circulatedto the Member Bodies for approval before their acceptance as InternationalStandards by the lSO Council.
Prior to 1972, the results of the work of the Technical Committees were publishedas ISORecommendations; these documents are now in the process of beingtransformed into International Standards. As part of this process，TechnicalCommittee lSO/TC 29 has reviewed lSO Recommendation R 866 and found ittechnically suitable for transformation.International Standard lSO 866 thereforereplaces lSO Recommendation R 866-1968 to which it is technically identical.This International Standard,relating to centre drills, dealsonly with centre drills for centre holes without protectingchamfers – Type A. The other types are dealt with inISO 2540，Centre drills for centre holes with protectingchamfer – Type B, and ISO 2541,Centre drills for centreholes with radius form – Type R.This international Standard specifies the dimensions ofcentre drills for centre holes without protecting chamfers — Type A.
lt covers only metric dimensions，regarded as the onlyrecommended dimensions in the future for this type ofdrill.
The flutes may be straight or spiral at the option of themanufacturer.
Unless otherwise indicated,these drills will be right-handcutting.
This International Standard includes an annex giving therecommended dimensions for the Type A centre holes,which can be obtained by a rational use of the centre drillslisted in this International Standard.Centre drills shall be designated by the type (in this case,Type A), the pilot diameter d (first column of table 1) andthe shank diameter d (second column of table 1).ISO 866 pdf download.