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IS0
I N T E R NAT1 ON AL OR GAN I ZATl O N F O R STAN DAR D I2 AT1 O N
IS0 RECOMMENDATION
R 297
7/24 TAPERS FOR TOOL SHANKS
1st EDITION
March 1963
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 297, 7/24 Tapers foor Tool Shanks, was drawn up by Techni-
cal Committee ISO/TC 39, Machine Tools, the Secretariat of which is held by the Association
Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1950, taking into account the
studies which had been made by the former International Federation of the National Standard-
izing Associations (ISA), and led, in 1955, to the adoption of a Draft IS0 Recommendation.
In July 1960, this Draft IS0 Recommendation (No. 389) was circulated to all the IS0
Member Bodies for enquiry. It was approved by the following Member Bodies:
Argentina Germany Poland
Australia Portugal
HWWY
Belgium India Romania
Chile Israel Spain
Colombia Italy Sweden
Switzerland
Czechoslovakia Japan
Denmark Netherlands United Kingdom
France New Zealand U.S.A.
U.S.S.R.
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 March 1963, to accept it as an IS0 Recommendation.
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ISOlR 297 - 1963 (E)
IS0 Recommendation R 297 March 1963
7/24 TAPERS FOR TOOL SHANKS
1. INTRODUCTION
The following tables deal with 7/24 tapers. They relate
on the one hand, to spindle noses Table 1, page 4, for millimetre sizes, and
Table 2, page 5, for inch sizes,
on the other hand, to tool shanks Table 3, page 6, for millimetre sizes, and
Table 4, page 7, for inch sizes.
This type of taper is designed especially for milling machine spindle noses, as well as for L-,e
corresponding tool shanks, and for this reason it is hoped to prepare a more comprehensive
IS0 Recommendation which will deal with “Spindle Noses with 7/24 Tapers for Milling Ma-
chines”.
2. INTERCHANGEABILITY
The present IS0 Recommendation provides, as regards threads, two entirely distinct types of
products according to the type of thread, M or UNC.
In order to distinguish between those two types, it is important that the component itself be
marked with the corresponding thread symbol, each national standards body being free to adopt,
in its national standard, either of the two threads.
For all other sizes, however, the products manufactured either to metric or to inch sizes are strictly
interchangeable, though not absolutely identical. Acceptance conditions, if provided for in
national standards, should therefore be such as to allow for the acceptance of products specified
either in inch or metric sizes.
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ISOIR 297 - 1963 (E)
3. 7/24 TAPERS FOR SPINDLE NOSES
3.1 Sizes in millimetres (6)
Cross-section XYZ
-tp-
TABLE 1. - 7/24 tapers for spindle noses
Designation 1 No.40 1 No.50 No.60 I
44.450 ' 69.850 1 107.950
Dl (9
~ -~
D2 h5 69.832 31*750 ~ 88.882 128.570 ~ 221.440
- - ~_________-
di H12 17.4 ~ 25.3 39.6 i 60.2-
.. - -~ - .
d2 min. ' 17 27 35
~~
140 220
~- ~- ._
M16 ~ M20
25 30
54 66.7 101.6 1 177.8
f (3>
~. ~~
m min. 1 12.5
19 1 38
~ 16
12.5 1 12.5
n max. I 8 ~ 8
O
-2 min. I 16.5 23 36
I
bl (4) I 15.9 1 15.9 1 25.4 1 25.4 I
c min. 8 18
__ _. -~
K max. 16.5 1 19.5 26.5
- _____-
z1 (5) 0.4 ~ 0.4 ~ 0.4
(I) Dl = basic size.
(2) g, = thread diameter: this is either a metric thread M with standard pitch or, if expressly stated, a UNC
thread (see Table 2 for sizes in inches). In every case, the appropriate symbol M or UNC should be
marked on the component.
(3) Tolerance on the position of fixing holes (maximum radial deviation from their theoretical position):
No. 30 and No. 40: 0.075 mm,
No. 50 and No. 60: 0.100 mm.
(4) M6/h5 fit for the assembly of the tenon in its slot. The dimension v corresponds to the permissible eccentricity
of the tenon 6,: it is the distance between the mid-plane of the teno
...