BS ISO 866:2016 pdf free
BS ISO 866:2016 pdf free.Centre drills for centre holes without protecting chamfers一Type A
BS ISO 866 specifies the dimensions of centre drills for centre holes without protecting chamfers (Type A).
It covers only metric dimensions, which are regarded as the only recommended dimensions in the future for this type of drill.
The flutes may be straight or spiral, depending on the manufacturer’s discretion.
Unless otherwise indicated, these drills will be right-hand cutting.
Recommended dimensions for Type A centre holes, which can be obtained by a rational use of the centre drills listed in this International Standard, are given in Annex A.
2 Dimensions
Dimensions of the centre drill shall be in accordance with the dimensions shown in Figures 1 and 2 and given in Table 1.
3 Designation
A centre drills in accordance with this International Standard shall be designated by the following:
a) the term “Centre drill”;
b) reference to this International Standard (e.g ISO 866);
c) Type A;
d) pilot diameter, d (in millimetres);
shank diameter, d1 (in millimetres).
EXAMPLE A centre drill type A, pilot diameter d = 0,63, shank diameter d1 = 3,15 is designated as follows:Centre drill ISO 866 – A 0,63/3,15
There are two methods for dimensioning type A centre holes (see Figures A.1 and A.2), which are practically equivalent. One or the other method may be used.
Dimension I depends on the length, I, of the centre drill. It should not, even in the case of drilling with re-sharpened centre drills, be less than the reference value, t, given in Table A.1.Dimension I depends on the length, I, of the centre drill. It should not, even in the case of drilling with re-sharpened centre drills, be less than the reference value, t, given in Table A.1.
For the relationship between the designations in this International Standard and preferred symbols in ISO 13399, see Table B.1.BS ISO 866 pdf free download.
