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IS0
I NT ERN AT I ON A L O RG A N IZ AT1 O N FOR STA N DARD IZATION
IS0 RECOMMENDATION
R 724
IS0 GENERAL PURPOSE METRIC SCREW THREADS
BASIC DIMENSIONS
1 st EDITION
May 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 724, IS0 general purpose metric screw threads - Basic dimen-
sions, was drawn up by Technical Committee ISO/TC 1, Screw threads, the Secretariat of which is
held by the Sveriges Standardiseringskommission (SIS).
Work on this question by the Technical Committee began in 1962 and led, in 1964, to the
adoption of a Draft IS0 Recommendation.
In September 1965, this Draft IS0 Recommendation (No. 782) 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 :
South Africa,
Argentina Germany
Rep. of
Australia Hungary
Spain
Austria India
Israel Sweden
Belgium
Italy Switzerland
Brazil
Turkey
Canada Japan
U.A.R.
Chile Netherlands
United Kingdom
Czechoslovakia New Zealand
Norway U.S.A.
Denmark
Poland U.S.S.R.
Finland
Romania Yugoslavia
France
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 May 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 724-1968 IE
IS0 Recommendation R 724 May 1968
IS0 GENERAL PURPOSE METRIC SCREW THREADS
BASIC DIMENSIONS
I. SCOPE
This IS0 Recommendation tabulates the basic dimensions for IS0 general purpose metric screw
threads according to IS0 Recommendation R 261 .* The values refer to the basic profile according to
IS0 Recommendation R h8.**
2. APPLlCATlON
When metric units are given in a national standard, the values should preferably be rounded to three
decimal places.
When a conversion to inch units is required, the following rules should be applied
divide the relevant figure, found in the tables, by 25.4;
(I)
round the value obtained to four decimal places.
(2)
3. CALCULATION
The values given in this IS0 Recommendation have been calculated from the following formulae.
The values have been given to six decimal places in order to enable a proper conversion to inch units
(see section 2).
D, = D-2X 3/8H = D-0.649519053Pmm
d, = d -2X3/8H = d -0.649519053Pmm
D, = D-7X 5/8H = D- 1.082531 755Pmm
d, = d-2X5/8H = d-1.082531755Pmm
where
D
is the basic major diameter for internal threads,
is the basic pitch diameter for internal threads,
D,
is the basic minor diameter for internal threads,
Dl
d is the basic major diameter for external threads,
is the basic pitch diameter for external threads,
d,
is the basic minor diameter for external threads,
d,
H is the height of fundamental triangle,
P is the pitch.
*
At present under revision under the new title, IS0 general purpose mem'c screw rhreads - General plan (Draft
IS0 Recommendation No. 1499).
** At present under revision under the new title, IS0 general purpose screw threads - Basic profile (Draft IS0
Recommendation No. 1498).
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ISO/R 724-1968 (I
4. BASIC DIMENSIONS IN MILLIMETRES
t--Y
Nominal
Major
Pitch
diameter
diameter diameter diameter
D. d
D2, d2
1 .O00 O00
0.837 620 1 0.729367
1.000 O00
0.870 096 0.783 494
I I
1 1 I 0.25 I 1.100000
0.937 620 0.829 367
1.1
0.2 1.100 O00
0.970 096
19 0.25 1.200 O00
1.-
I 0.2 I 1.200 O00
1.400 O00
1.400 O00
1.270 096 1.183 494
1.600 O00
0.2
1.572 668
1.421 114
1.8
1.800 O00
0.2 1.670 096 1.583 494
1.740 192
1.566 987
1.837 620 1.729 367
1.907 716
1.712 861
2.037 620 1.929 367
2.207 716 2.012 861
2.5 I I 2.500000
0.35
2.272 668 7.121 114
2.675 240 2.458 734
2.772 668
2.621 114
3.1 10 289
2.850 48 1
3.272 668 3.121 114
3.545 337 3.242 228
3.675 240 3.458 734
4.012 861 3.688 101
4s
4.500 O00
0.5
4.175 240 3.958 734
4.480 385 4.133 975
o.8 5.000 O00
I 0.5 I
I I
5.5 1 0.5 I 5.500 O00
I. I
6.000 O00
5.512 861 5.188 101
6.350 48 1
5.917 468
7.000 O00
0.75
6.512 861
6.188 101
1.25 7.188 101 6.646 835
8
1 8.000 O00 7.350 48 1 6.917 468
7.512 861
7.188 101
>- 9.000 O00 8.188 101
7.646 835
8.350 48 1
7.917 468
I 0.75 I
! 8.512 861 8.188 101
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ISO/R 724-1968 (E)
4. BASIC DIMENSIONS IN MILLIMETRES (continued)
Nominû Major Pitch
Minor
Pitch
diameter diameter diameter
diameter
P
D, d
D2, d2 DI, dl
1.5 9.025 721 8.376 202
1.25 9.188 101 8.646 835
10 10.000 O00
1 9.350 481
8.917 468
0.75
9.512 861 9.188 101
1.5 10.025 721 9.376 202
11 1 1 1 .O00 O00
10.350 481 9.917 468
0.75 10.512 861 10.188 101
1.75 10.863 342 10.105 569
_-
1.5 11.025 721 10.376 202
12 12.000 O00
1.25 11.188 101
10.646 835
1 11.350 481 10.917 468
2 12.700 962 1 1.834 936
1.5 13.025 721 12.376 202
14.000 O00
14
1.25 13.188 101 12.646 835
1 13.350 481 12.917 468
1.5 14.025 721 13.376 202
15 15.000 O00
1 14.350 481 13.917 468
2
14.700 962 13.834 936
16 1.5 16.000 O00 15.025 721 14.376 202
1 15.350 481 14.917 468
1.5 16.025 721 15.376 202
17 17.000 O00
1 16.350 481 15.917 468
2.5
16.376 202 15.293 671
2 16.700 962 15.834 936
18.000 O00
18
1.5 17.025 721 16.376 202
1 17.350 481 16.917 468
2.5 18.376 202 17.293 671
2 18.700 962 17.834 936
20 20.000 O00
I
1.5 19.025 721 18.376 202
1 19.350 481 18.917 468
2.5 20.376 202 19.293 671
2 20.700 962 19.834 936
22 22.000 O00
1.5 21.025 721 20.376 202
1 21.350 481 20.9 17 468
3 22.051 443 20.752 405
2 22.700 962 2 1.834 936
24 24.000 O00
1.5 23.025 721 22.376 202
1 23.350 481 22.917 468
2
23.700 962 22.834 936
25 1.5 25.000 O00 24.025 721 23.376 202
1 24.350 481 23.917 468
26 1.5 25.025 721 24.376 202
26.000 O00
3 25.05 1 443 23.752 405
2 25.700 962 24.834 936
27 27.000 O00
1.5 26.025 721 25.376 202
1 26.350 481 25.917 468
2 26.700 962 25.834 936
28 1.5 28.000 O00 27.025 721 26.376 202
1 27.350 481 26.917 468
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ISO/R 724-1968 (E)
4. BASIC DIMENSIONS IN MILLIMETRES lconfinued)
Nominal Major Pitch
Minor
diameter Pitch diameter
diameter diameter
Dl? d2
DI, dl
27.726 683
26.21 1 139
28.05 1 443
26.752 405
30 1 1 30.000 O00
28.700 962 27.834 936
29.025 721
28.376 202
29.350 481
28.9 17 468
30.700 962
29.834 936
32.000 O00
3 1 .O25 72 1
30.376 202
3.5 30.726 683
29.211 139
3 3 1 .O5 1 443
29.752 405
33
33.000 000
3 1.700 962
30.834 936
I s.5 I
32.025 721
3 1.376 202
35
1.5 35.000 000 34.025 721
33.376 202
4
33.401 924
3 1.669 873
34.051 443 32.752 405
34.700 962 33.834 936
35.025 721
34.376 202
I I
38 I 1.5 I 38.000 O00
37.025 721 36.376 202
4
36.401 924 34.669 873
3
37.051 443
35.752 405
39 39.000 O00
2 37.700 962 36.834 936
1.5
38.025 721
37.376 202
3
38.051 443 36.752 405
40 2 40.000 000
38.700 962 37.834 936
1.5
39.025 721 38.376 202
4.5
39.077 164 37.128 607
4
39.401 924 37.669 873
42 I 1 42.000000
40.051 443 38.752 405
40.700 962
39.834 936
41.025 721
I 1.5 I 40.376 202
4.5
42.077 164--
40.128 607
4
42.401 924 40.669 873
45 .O00
...