This Pakistan Standard specifies the dimensions of Centre drills for centre holes with protecting chamfer—Type B.
It covers only metric dimensions regarded as the only recom mended dimensions in the future for this type of drills.
The flutes may be straight or spiral at the option of the manufacturer.
Unless otherwise stated these drills will be right-hand cut ting.
This Pakistan Standard includes an Annex giving the re commended dimensions for the centre holes, Type B, which can be obtained by a rational use of the centre drills listed in this international Standard.
PS 1364-1975 history
1975PS 1364-1975 SPECIFICATION FOR CENTRE DRILLS FOR CENTRE HOLES WITH PROTECTING CHAMFER—TYPE-B