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Ref. No.: ISO/R 239 - 1961 (E)
IS0
I N TER NAT1 O N AL O R GAN I Z AT1 O N F O R STAN DAR D I Z AT1 O N
I S O R E 6 O M M EN D AT1 O N
R 239
DRILL CHUCK TAPERS
1st EDITION
December 1961
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards belongs to
IS0 Member’Bodies. Reproduction of these documents, in any country,
may be authorized therefore only by the national standards organization
of that country, being a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national
standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 239, Drill Chuck Tapers, was drawn up by Technical Committee
ISO/TC 29, Small Tools, the Secretariat of which is held by the Association Française de Normalisa-
tion (AFNOR).
Work on this question by the Technical Committee began in 1952and led,in 1958,to the
adoption of a Draft IS0 Recommendation.
L
In September 1959, this Draft IS0 Recommendation (No. 305) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies :
Austria Hungary Portugal
Romania
Belgium India
Burma Italy Sweden
Czechoslovakia Mexico Switzerland
France Netherlands United Kingdom
Germany Pakistan U. S. A.
U. S. S. R.
Greece Poland
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in December 1961, to accept it as an IS0 RECOMMENDATION.
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ISO/R 239 - 1961 (E)
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IS0 Recommendation R 239 Decem ber 1961
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DRILL CHUCK TAPERS
INTRODUCTION
I. SCOPE
This IS0 Recommendation relates to drill chuck tapers and deals with two distinct types:
1. Morse taper type . Tables 1.1 and 1.2,
2. Jacobs taper type . Tables 2.1 and 2.2.
For each type of taper, this IS0 Recommendation comprises two tables giving respectively :
(1) the dimensions in millimetres and
(2) the corresponding dimensions in inches.
II. INTERCHANGEABILITY
For each type of taper, Morse or Jacobs, complete interchangeability is assured between the two
systems of units of measurement, millimetres and inches, as the dimensions expressed in any one
system have been converted from those expressed in the other with sufficiently close approximation,
having regard to the magnitude of the tolerances.
III. MORSE TAPER TYPE
Tables 1.1 and 1.2 relate to drill chuck tapers of the Morse taper type.
The tapered portions are idpntical with Morse tapers :
1 for tapers B10 and B12,
2 for tapers B16 and B18,
3 for tapers B22 and B24.
The length of each of these tapers is, of course, distinctly less than the overall length of the cor-
respo
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