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IS0
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I N T E R N ATI O NA L - QRGA-RI-ZATI O N F O R s TAFDM AT I O N
494
PARALLEL SHANK TWIST DRILLS -
LONG SERIES
A u g u st 1 96
"')
.'i
be authorized therefore only
rinted in Switzerland
---------------------- Page: 1 ----------------------
,/’
BRIEF HISTORY
The IS0 Recommendation R 494, Parallel Shank Twist Drills -Long Series, was drawn
up by Technical Committee ISO/TC 29, Small 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 1962 to the adoption of a Draft IS0 Recommendation.
In April 1964, this Draft IS0 Recommendation (M. 663) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subjec;tto a few modifications of an editorial
nature, by the following Member Bodies:
/
Argentina
France ,I Poland
Austria Germany’’
Portugal
Belgium Hungafi Spain
Brazil India/ Sweden
Canada Itay Switzerland
Turkey ._
Chile
Ja$an ---.
‘\
Colombia
rea, Rep. of United Kingdom
i
Czechoslovakia etherlands U.S.S.R.
Denmark ew Zealand Yugoslavia
One Member Body opposed the a roval of the Draft: U.S.A.
k-. _-
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Coun-
cil, which decided, in August 1966, to accept it as an IS0 RECOMMENDATION.
I
,/
/’
-2-
---------------------- Page: 2 ----------------------
ISOlR 494 - 1966 (E)
PARALLEL SHANK TWIST DRILLS -
LONG SERIES
This
c&rallel shank twist drills, i.i LU . Z
and tub eries,
B§
comprises three tables giving respectively ,'
A
a a) the recommended dimensions in millimetres,'
the recommended dimensions in inches;
the corresponding lengths, in millimetres and in inches, set out as functions of diameter steps.
€I. INTERCHANGEABILITY
The numerical tables have been drawn up in such a way as to ensure that the standard dimensions
in millimetres and inches correspond as closely as possible.
To this end, the complete range of diameters has been subdivided into a number of steps, the
limits of which have been derived from the preferred number series for the metric values and
converted directly from those for the inch values; the lengths remain the same for the metric
and for the inch values, within a given step.
The recommended diameters in the two systems of units of measurement differ, however, and
the number of recommended diameters, in a given step, also differs in one system from that in
the other.
Finally, the tolerance on the diameter of the cutting portion has been standardized solely on the
basis of the metric values of h8, * converted directly into inches for inch drills.
..
*p IS0 System of &mils andktsdb- 'i fl
-3-
---------------------- Page: 3 ----------------------
ISOlR 494 - 1966 (E)
,Recess optional
1
3.1 Recommended dimensions in millimetres
- -
d d I I d
Il I I 11 d Il
11
- - - - -
I
1 .O0 8.80
33 j 56 3.60 6.20
73 112
8.90
1.10 37 ~ 60 6.30
3.70
___
1.20 9.00
3.80 6.40
97 148
41 65
1.30 9.10
3.90 6.50
115
~-
1.40 78 119
9.20
4.00 6.60
45
1.50 9.30
4.10 6.70
-~
1.60 9.40
4.20 6.80
50 76
1.70
9.50
4.30 6.90
~
1.80 9.60
4.40 7.00
80
53
82 126
1.90 9.70
4.50 7.10
___
102 156
2.00 9.80
7.20
4.60
56 85
2.10
7.30 9.90
4.70
~__ ~
~
2.20 10.00
4.80 7.40
59 90
121
2.30 7.50 10.10
4.90
.~ -
2.40 10.20
5.00 7.60
87 132
2.50 62 95 me--
5.10 7.70
c-,
~-
2.60 10.40
5.20 7.80
~
10.50
2.70 5.30 7.90
___
__
2.80 8.00 10.60
5.40
109 165
1 O0
66
2.90 8.10 10.70
5.50
8.20 10.80
3.00 5.60
~
139
91
10.90
3.10 5.70 8.30
106 11 .O0
3.20 69 5.80 8.40 128
3.30 5.90 8.50 11.10
~ __ ~. ~
11.20
3.40 6
...