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Ref. NO.: ISO/R 235 - 1881 (E)
IS0
I NTERNATI O NAL ORGANIZATION FOR STAN DARD1 ZATl ON
IS0 RECOMMENDATION
R 235
PARALLEL SHANK TWIST DRILLS
JOBBER AND STUB SERIES
AND MORSE TAPER SHANK TWIST DRILLS
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 eac-. 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.
---------------------- Page: 1 ----------------------
BRIEF HISTORY
The IS0 Recommendation R 235, Parallel Shank Twist Drills, Jobber and Stub Series, and
Morse Taper Shank Twist Drills, 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 1947, taking into account the
studies which had been made by the former International Federation of the National Standardizing
Associations (ISA), and led, in 1958, to the adoption of a Draft IS0 Recommandation.
In September 1959, this Draft IS0 Recommendation (No. 301) was submitted to all the IS0
Member Bodies for enquiry. It was approved, subject to some editorial amendments, by the
following Member Bodies:
Austria Hungary Portugal
Belgium India Romania
Burma Italy Sweden
Czechoslovakia Mexico Switzerland
France Netherlands United Kingdom
Germany Pakistan U. S. S. R.
Greece Poland
Two Member Bodies opposed the approval of the Draft:
Canada, 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.
-2-
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[SOIR 235 - IS61 (E)
IS0 Recommendation R 235
ERRATUM
April 1983
PARALLEL SHANK TWIST DRILLS
JOBBER AND STUB SERIES
AND MORSE TAPER SHANK TWIST DRILLS
1st Edition - December 1961
Flrst Printing - June 1902
ERRATUM
Page 13, Note 3. Shank, 3rd line,
in place of .** dealing with 5 per cent tapers for tool shanks ”,
read: “. . .** dealing with self-holding tapers for tool shanks ”.
---------------------- Page: 3 ----------------------
ISO/R 235 - I961 (E)
IS0 Recommendation
R 235
Decem ber 1961
PARALLEL SHANK TWIST DRILLS
JOBBER AND STUB SERIES
AND MORSE TAPER SHANK TWIST DRILLS
INTRODUCTION
I. SCOPE
This IS0 Recommendation relates to twist drills and deals with the following three types:
1, Parallel shank twist drills, stub series. . . . . . . . . . . . . . Tables 1.1 to 1.3,
2. Parallel shank twist drills, jobber series . . . . . . . . . . . . . Tables 2.1 to 2.3,
3. Morse taper shank twist drills and core drills . . . . . . . . . . Tables 3.1 to 3.3.
c __- -
Other types of twist drills will be dealt with in further IS0 Recommendations as and when current
work on them is completed.
For each type of drill mentioned above, the IS0 Recommendation comprises three tables giving
respectively :
(1) the recommended dimensions in millimetres,
(2) the recommended dimensions in inches,
(3) the corresponding lengths, in millimetres and in inches, set out as functions of diameter
steps.
II. 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 con-
verted directly from those for the inch values; the lengths and taper shank dimensions remain
the same for the metric and 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.
* IS0 System o,f Limits and Fits.
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ISO/R 235 - 1961 (E)
1. PARALLEL SHANK TWIST DRILLS, STUB SERIES
i
t
1.1 Recommended dimensions in millimetres
-
-
I I
d I 4 1
1
-
-
20 84 18.50 I
27.50
I
24 18.75 I 64
127
27.75 81 162
____
26 10.00 19.00
28.00
-_
43 89 __
30
10.20 19.25
28.25
32
10.50 19.50
28.50
__
_____
66 131
1.80 36 10.80
28.75
38 11.00 20.00
29.00
84 168
40 95 20.25
29.25
~.
43
11.50 20.50
29.50
__ -
68 136
2.80 11.80 20.75
29.75
~
16 46
3.00
12.00 21.00 30.00
__
.~
3.20 18 49
12.20 21.25 30.25
-___
3.50 20 52 21.50
12*50 30.50
~
__~
102
3.80 12.80 21.75 70 141 30.75
I 51
87 174
4.00 22 55 13.00 22.00 31.00
-
-.___
4.20 13.20 22.25 31.25
~
--
4.50 24 58 22.50
31.50
~__
4.80 107 22.75
3 1.75
____ ____
5.00 26 62 14.00 23.00 72 146
32.00
__c
5.20 14.25 23.25 32.50 90
180
~
5.50 14.50 23.50 33.00
__-
____
111
5.80 28 66 14.75 23.75 1- 33.50
-~ ______.
__ __
6.00 15.00 24.00 I 34.00
---
6.20 34.50
____.
70 151
31 93 186
35.00
6.50 01 75
___.
115
6.80 15.75 35.50
__
7.00 36.00
~.
34 74
7.20 36.50
______.
96 193
37.00
___.
119
QI 6o 25*75 37.50
7.80 I
156
78
26.00 I 38.00
____.
37 79
26.25 38.50
26.50 39.00 100
8.50 I 200
-___ __
123
26.75 39.50
8.80 I
~.
84 27.00 81 162 40.00
127 27.25
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ISO/R 235 - 1961 (E)
1.2 Recommended dimensions in inches
-
--
I
I
I
47/32
Ys
6"s
9 26
41
164 /sa
164
2'13 W16
6
21
/sa 7i8
Is2
11 16
164 Il6
"164 I
"/32
61
164
13
Il6 W16
63
164
27
/sa
3%
V16
29
69
~~
331~ 1 7/16
5l6Il6 "164
"/64 216/16
81
/3z
63
164
4
"164 I
Nom relating to Tables 1.1 and 1.2
1. Intermediate sizes
When intermediate sizes are specially required, reference should be made to the General
Table 1.3 for the corresponding lengths.
2. Cuttingportion
- Tolerance on diameter d measured near the point: h8*.
For dimensions in inches, direct conversion into inches of the metric values of h8.
- Back taper: at the manufacturer's discretion.
- Hand of cutting, unless otherwise specified: right.
3. Shank
These drills are normally made without driving tenon.
4. Tolerance on lengths
See General Table 1.3.
* H'b System of Limits and Fits.
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lSO/R 235 - 1961 (E)
1.3 General Table: Corresponding lengths, in millimetres and in inches, set out as functions of
diameter steps
Diameter ranges d I Corresponding lengths
over I incl.
mm
0.19 0.24
-__
0.24 0.30
-_____~ __
0.30 0.38
_ ____ ~
0.38 0.48 -
0.48 0.53
~ __
_.______
4.25 I 4.75
_-____
4.75 I 5.30
- __~ ______ -
5.30 6.00
-___________._
6.00 6.70
_____--
- 6.70 - 7.50
7.50 8.50
- 8.50 9.50
9.50 10.60
10.60 11.80
~~
13.20 -
11.80
-~
- 13.20 14.00
14.00 15.00 ~-
15.00 16.00
~__~~
16.00 17.00
~~ ~
I
17.00 18.00
20.00 -I 21.20
21.20 22.40
23.60
22.40
23.60 25.00
25.00
~~ 26.50 - ~ ff
28.00
30.00 1 31.50
-
31.50 1 33.50
33.50 __ -~ 35.50
- 35.50 37.50
37.50 ~ 40.00
NOTES
1. Tolerance on lengths
Lengths 1 and IL may vary, within one diameter step, between the minimum and maximum
limits corresponding respectively to the figures given for the nearest lower or upper step.
(See as examples note 1, pages 9 and 15.)
2. Recommended diameters in millimetres and in inches : see Tables 1.1 and 1.2.
-6-
---------------------- Page: 7 ----------------------
lSO/R 235 - 1961 (E)
2. PARALLEL SHANK TWIST DRILLS, JOBBER SERIES
2.1 Recommended dimensions in millimetres
-
-
d
1 d 1
d
l d
d I 11
-
-
-
0.20
1.35
3.50 7.30
11.10
~
___ ___
0.22
1.40 3.60
7.40 69 109
11.20
~
~
18
40
0.25
1.45 3.70
7.50 11.30
-~
~
-__
0.28 1.50
3.80 7.60
11.40
-~
__ __
19
0.30 1.55
3.90 7.70
11.50
__
___
0.32 1.60
4.00 7.80 11.60
~ ___ ~
20 43
0.35 4 1.65 4.10
7.90 11.70
~ ~
0.38 1.70 4.20
8.00 11.80
__ ~ ~
75 117
0.40 1.75 4.30 8.10
11.90
__-
.~
0.42 1.80 4.40 8.20 12.00
~-
~
5 20 22 46
0.45 1.85
4.50 47 80 8.30 12.10
__ - -~
0.48 1.90
4.60 8.40 12.20
~
0.50 1.95 4.70 8.50
12.30
~
~ ___
6 22
0.52 2.00 4.80 8.60 12.40
~
49
24
0.55 2.05 4.90 8.70 12.50
~ __
0.58 7 24 2.10 5.00 8.80 12.60
___ ~
52 86
0.60 2.15 5.10 8.90 12.70
__ -- ~-
__
0.62 2.20 9.00 12.80
5.20
~ ~
8 26 81 125
0.65 2.25 53 5.30 9.10 12.90
27
__ __ ~
0.68 2.30 5.40 9.20 13.00
~- __
~-
0.70 2.35 5.50 9.30 13.10
~
9 28
0.72 2.40 5.60 9.40 13.20
~ ~
9.50 13.30
0.75 2.45 5.70 57 93
~ ~ ~
0.78 2.50 5.80 9.60 13.40
_ . -
___
30 57
0.80 2.55 5.90 9.70 13.50
~ -~
~
10 30
13.60
0.82 2.60 6.00 9.80
___ ___
9.90 13.70
0.85 2.65 6.10
~ ~
6.20 10.00 13.80
0.88 2.70
~
6.30 10.10 87 133 13.90
0.90 2.75
~~
11
32
14.00
6.40 63 101 10.20
0.92 2.80
~
~
14.25
0.95 2.85 33 61 6.50 10.30
~
~
10.40 14.50
0.98 2.90 6.60
~ ~
10.50 14.75
1 .oc 12 34 2.95 6.70
~
~
6.80 10.60 15.00
1 .O5 3.00
--
10.70 15.25
3.10 6.90
1.1c
-
~
-~
14 36
7.00 69 109 10.80 15.5C
1.15 3.20 36 65
~ ____
94 142
10.90 15.75
1.2c 3.30 7.10
.
~ __-
16.0C
70 7.20 11 .O0
1.2: 16 38 3.40 39
__ --
1.3C
- - -
-7-
---------------------- Page: 8 ----------------------
lSO/R 235 - 1961 (E)
2.2 Recommended dimensions ln inches
2l5Il6
3 'I1 6
*CI .
3V16
29
164
"/32
31
164
3'l/3a
Noms relating to Tables 2.1 and 2.2
1. Intermediate sizes
When intermediate sizes are specially required, reference should be made to the General
Table 2.3 for the correspoqding lengths.
2. Cuttingportion
- Tolerance on diameter d measured near the point: h8*.
For dimensions in incheq, direct conversion into inches of the metric values of h8.
- Back taper: at the manufacturer'
...