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IS0
I NTERNATI ON AL ORGAN1 ZATlO N FOR STAN DARDI ZATl O N
IS0 RECOMMENDATION
R 238
REDUCTION SLEEVES AND EXTENSION SOCKETS
FOR TOOLS WITH MORSE TAPER SHANKS
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 238, Reduction Sleeves and Extension Sockets for Tools with
Morse Taper Shanks, was drawn up by Technical Committee ISO/TC 29, Small Tools, the Secre-
tariat of which is held by the Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1952 and led, in 1958, to the
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adoption of a Draft IS0 Recommendation.
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In September 1959, this Draft IS0 Recommendation (No. 304) was circulated to aii the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies :
Belgium India Romania
Burma Italy Sweden
Czechoslovakia Mexico Switzerland
France Netherlands United Kingdom
Germany Pakistan U. S. S. R.
Greece Poland
Hungary Portugal
One Member Body opposed the approval of the Draft: U. S. A.
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 238 - 1961 (E)
Decem ber 1961
IS0 Recommendation R 238
REDUCTION SLEEVES AND EXTENSION SOCKETS
FOR TOOLS WITH MORSE TAPER SHANKS
INTRODUCTION
I. SCOPE
This IS0 Recommendation relates to the following two pieces of equipment:
1. Reduction sleeves for tools with Morse taper shanks . . . . . . Tables 1.1 and 1.2,
2. Extension sockets for tools with Morse taper shanks . . . . . . Tables 2.1 and 2.2.
For each of them, the IS0 Recommendation comprises two tables giving respectively :
(1) the dimensions in millimetres and
(2) the corresponding dimensions in inches.
II. INTERCHANGEABILITY
The numerical values given in this IS0 Recommendation, whether in millimetres or in inches,
automatically ensure interchangeability with the corresponding machines and tools, whatever
the system of units employed.
The mating dimensions of the sleeves and sockets are in fact in accordance with those specified
in the IS0 Recommendation R . . .* for Morse taper shanks, which were determined so as to
give the same guarantee of interchangeability.
III. REDUCTION SLEEVES
In the reduction sleeves dealt with in Tables 1.1 and 1.2, in millimetres and in inches, the inside
taper is always strictly the same as the standard Morse taper of the same number, even in its
length.
The same applies to the outside taper, except for the length, however, which is sometimes equal to,
sometimes greater than, that of the standard taper of the same number.
IV. EXTENSION SOCKETS
The statements made above concerning the Morse taper dimensions of the reduction sleeves are
equally applicable to the extension sockets, under the same conditions.
Tables 2.1 and 2.2, in millimetres and in inches, also specify for the latter the diameter of the
parallel portion and the minimum value for the total length Z2.
Lengths Z2 above this minimum should be selected to suit requirements, but preference should
be given to multiples of 5 mm or 1/4 inch, or even 10 mm or l/z inch**.
* In course of preparation.
** It is the responsibility of each IS0 Member Body to specify this minimum in its national standard, giving either the
minimum value shown in the tables or the slightly larger one indicated in the relevant note as “ Reinforced minimum”.
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ISO/R 238 - 1961 (E)
1. REDUCTION SLEEVES FOR TOOLS WITH MORSE TAPER SHANKS
,- Inside Morse toper
Outside Morse toper -,
- I
4 t
Example of the method of designating a reduction sleeve with outside Morse taper 4, and inside Morse taper 2:
Reduction sleeve Morse 4 x 2.
1.1 Dimensions in millimetres
Outside taper Inside taper
I
M.T. M.T. ~ dl
d ~I I a1
-
2 1
...