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IS0
I NTERN AT I O N A L O RG A N IZATl O N FOR STAN DA RDlZ AT1 ON
IS0 RECOMMEN DATION
R 839
MILLING MACHINE ARBORS WITH 7/24 TAPERS
AND MILLING MACHINE ACCESSORIES
1st EDITION
October 1968
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 839, Milling machine arbors with 7/24 tapers and milling machine
accessories, was drawn up by Technical Committee ISO/TC 29, Small fools, the Secretariat of which
is held by the Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1958 and led, in 1965, to the
adoption of a Draft IS0 Recommendation.
In June 1966, this Draft IS0 Recommendation (No. 938) 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 :
Argentina Hungary Netherlands
Belgium India Poland
Brazil Ireland Portugal
Chile Israel Spain
Czechoslovakia Italy Sweden
France Japan Turkey
Greece Korea, Rep. of United Kingdom
Three Member Bodies opposed the approval of the Draft :
Germany
Switzerland
U.S.A.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided,in October 1968, to accept it as an IS0 RECOMMENDATION.
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CONTENTS
Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 'I
1.Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2. Choice of dimensions and tolerances . . . . . . . . . . . . . . . . . . . . . . . . '/
2.1 Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Tolerances. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Recommended dimensions fur the metric series
3.1 Arbor dimensions
3.1.1 Principal dimensions , . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.2 Pilot at end of arbor . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.3 Protective boss at end of arbor . . . . . . . . . . . . . . . , . . . . . . . 10
3.2 Milling machine accessories
3.2.1 Spacing collars . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1
3.2.2 Bearing collars . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2.3 Clamping nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4. Recommended dimensions for the inch series
, 4.1 Arbor dimensions
L 4.1.1 Principal dimensions . .
...............
.... 13
4.1.2 Pilot at end of arbor . . .
....
13
4.2 Milling machine accessories
4.2.1 Spacing collars . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2.2 Bearing collars . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2.3 Clamping nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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ISO/R 839-1%8 (E)
IS0 Recommendation R 839 October 1968
MILLING MACHINE ARBORS WITH 7/24 TAPERS
AND MILLING MACHINE ACCESSORIES
INTRODUCTION
During the preparatory work on this IS0 Recommendation it was found that existing conditions with regard
to industrial equipment made it impossible to unify milling machine arbors and their accessories in a manner
which would be satisfactory both to countries using the metric system and to those using the inch system.
This IS0 Recommendation therefore standardizes two completely distinct series of arbors and accessories.
There is thus no interchangeability between these two series which are based respectively on the metric and inch
series of IS0 Recommendation R 240*. There are many features which are not strictly identical in both types,
the only interchangeable elements being the shanks with 7/24 tapers in accordance with IS0 Recommendation
R 297**.
1. SCOPE
This IS0 Recommendation, concerning miliing machine arbors with 7/24 tapers and their accessories (spacing
collars, bearing collars and clamping nuts), gives two completely distinct series of recommended manufacturing
dimensions :
- the one, for the metric series, is covered by the various tables in section 3;
- the other, for the inch series, is covered by the various tables in section 4.
2. CHOICE OF DIMENSIONS AND TOLERANCES
2.1 Dimensions
The diameters which have been adopted in this IS0 Recommendation as those most commonly used
correspond to the values given in IS0 Recommendation R 240* from 16 to 100 mm (omitting
19 mm and 70 mm) for the metric series and from 0.625 to 2.500 in for the inch series.
The shoulder, whether parallel or tapered, between the flange of diameter Dl and the parallel portion
of diameter d, is optional and is not generally found in the inch series. With or without the shoulder,
however, the diameter of the flange locating face should not in any case be less than Dz .
Interchangeability dimensions for milling cutters and cutter arbors.
** 7/24 tapers for tool shanks.
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ISO/R 839-1968 (E)
The dimensions of spacing collars, bearing collars and clamping nuts are given respectively in
clauses 3.2.1, 3.2.2 and 3.2.3 for the metric series and in clauses 4.2.1, 4.2.2 and 4.2.3 for the
inch
...