Introduction
The notes below are outline in nature and are very much second best to the standards
identified. Quality information is best found in the standards.
The notes on this page identify the basic ISO thread form and illustrate how the
tolerances related to the thread form are developed from the simple rules provided in
the relevant Standards. Using the equations and tables available on this page it
is possible to obtain the limits for all available dia-pitch-tolerance class
combination.
The standard BS 3643 Part 1 relates to single start parallel screw threads of sizes
from 1 to 300 mm. Part 2 provides selected limits of sizes for the rang of
screw threads.
The ISO standards quoted below are very similar
the the British standards and provide essentially the same information. The
Standard ISO 965 Part 2 (size range 1-64mm)provides much more limited information
compared to BS 3643 Part 2. ( size range 1-300mm ).
A table of ISO form screw threads from 1,6 to 300mm is found on ISO
screw threads. This table relates to a medium tolerance grade
screw nut combination (6H/6g) which is the grade implied if it is not specified.
Relevant Standards
BS 3643 Part 1:2007..ISO metric screw threads. Principles and basic data
BS 3643 Part 2:2007..ISO metric screw threads. Specification for selected limits of size
BS 3692:2001..ISO metric precision hexagon bolts, screws and nuts. Specification
BS ISO 965-1:1998 ...ISO general purpose metric screw threads. Tolerances (g.p.s.t.T). Principles and basic data
BS ISO 965-2:1998 ...ISO g.p.s.t.T . Limits of sizes for general purpose external and internal screw threads. Medium quality
BS ISO 261:1998 ...ISO general purpose metric screw threads. General plan
Tolerance selection Example
1) Tolerances for a M20 coarse thread medium fit.
The pitch for a M20 coarse thread is 2,5mm....Pitch
For the normal commercial applications a 6H/6g... Tolerance Selection
External Thread
Calculating the limits for the external thread diameter (d)
Fundamental deviation for es (g) = -42 μm.... Fundamental Deviation
The diameter tolerance width for an M20 g6 is 335μm. ....Tolerance Widths
The limits for d is therefore (max = 20 - 0,042 = 19,958 ),(min = 19.958 -0,335 = 19,623 )
Ans(max 19,958, min19,623 )
Calculating the limits for the external thread pitch diameter (d 2)
The basic pitch diameter is 20 - 2*0,32476.P = 18,3762
Fundamental deviation es = -42 μm. ...Fundamental Deviation
The pitch tolerance width (Td2) for an M20 g6 is 170μm..... Tolerance Widths
The limits for d 2 is therefore (max = 18,3762 - 0,042 = 18,334 ),(min = 18.334 -0,170 = 18,164 )
Ans(max 18,334, min 18,164 )
Calculating the limits for the external thread root diameter (d 3)...
Root Contours
The basic root diameter d1 is 20 - 2*0,54127.P = 17,294
To obtain the minimum root dia d3min first calculate
z = H/4 + Td2 /2 - P/8 = 0.21651P + 0,170/2 -0,125P = 0,3138
d 3min = d1 - es -2z = 17,294 - 0.042 - 2*0,0,3138 = 16.624
The tables in the standards do not include a table value for d 3max
The table on this website ( Screw Threads ) uses a value d 3max = d1 - es. = 17,252...
This is the diameter of the Go-Gauge Profile.
A value more in line with the
recommendations in the standards can be found using the equations found on this page Root Contours
(I will update the table in line with these recommendations over time - (R.B. 6/3/2008)
Internal Thread
Calculating the limits for the internal thread Minor diameter (d1)
The basic minor diameter d1 = 20 - 2*0,54127.P = 17,294
Fundamental deviation for EI(H) = 0 μm.... Fundamental Deviation
The diameter tolerance width for an M20 H6 is 450μm. ....Tolerance Widths
The limits for d is therefore (min = 17,294 + 0 = 17,294 ),(max = 17,294 + 0,450 = 17,744 )
Ans(max 17,744, min 17,294 )
Calculating the limits for the internal thread pitch diameter (d 2)
The basic pitch diameter is 20 - 2*0,32476.P = 18,3762
Fundamental deviation EI = 0 μm. ...Fundamental Deviation
The pitch tolerance width (Td2) for an M20 H6 is 224μm..... Tolerance Widths
The limits for d 2 is therefore (min = 18,376 + 0 = 18.376 ),(max = 18.376 + 0,224 = 18,600 )
Ans(max 18,334, min 18,164 )
Calculating the limits for the internal thread major diameter D
The basic Major diameter D is 20
The minimum major dia Dmin = 20,000
The Standards do not include a table value for D max
It also does not seem to give guidance on how to obtain. They simply state that
the thread should not transgress the basic profile.< /p>
Basic Thread Profile to BS 3643
Table of Basic Profile Dimensions
| |
H |
5/8H |
3/8H |
H/4 |
H/8 |
H/6 |
| Pitch |
0,86603P |
0,54127P |
0,32476P |
0,21651P |
0,10825P |
0,144337P |
| mm |
mm |
mm |
mm |
mm |
mm |
mm |
| 0,2 |
0,17320508 |
0,10825318 |
0,0649519 |
0,04330128 |
0,02165064 |
0,02886752 |
| 0,25 |
0,21650635 |
0,13531648 |
0,08118988 |
0,0541266 |
0,0270633 |
0,0360844 |
| 0,3 |
0,25980762 |
0,16237977 |
0,09742785 |
0,06495192 |
0,03247595 |
0,04330127 |
| 0,35 |
0,30310889 |
0,18944307 |
0,11366583 |
0,07577724 |
0,03788861 |
0,05051815 |
| 0,4 |
0,34641016 |
0,21650636 |
0,1299038 |
0,08660256 |
0,04330127 |
0,05773503 |
| 0,45 |
0,38971143 |
0,24356966 |
0,14614178 |
0,09742788 |
0,04871393 |
0,0649519 |
| 0,5 |
0,4330127 |
0,27063295 |
0,16237975 |
0,1082532 |
0,05412659 |
0,07216878 |
| 0,6 |
0,51961524 |
0,32475954 |
0,1948557 |
0,12990384 |
0,06495191 |
0,08660253 |
| 0,7 |
0,60621778 |
0,37888613 |
0,22733165 |
0,15155448 |
0,07577723 |
0,1010363 |
| 0,75 |
0,64951905 |
0,40594943 |
0,24356963 |
0,1623798 |
0,08118989 |
0,10825318 |
| 0,8 |
0,69282032 |
0,43301272 |
0,2598076 |
0,17320512 |
0,08660254 |
0,11547005 |
| 1 |
0,8660254 |
0,5412659 |
0,3247595 |
0,2165064 |
0,10825318 |
0,14433757 |
| 1,25 |
1,08253175 |
0,67658238 |
0,40594938 |
0,270633 |
0,13531648 |
0,18042197 |
| 1,5 |
1,2990381 |
0,81189885 |
0,48713925 |
0,3247596 |
0,16237977 |
0,21650635 |
| 1,75 |
1,51554445 |
0,94721533 |
0,56832913 |
0,3788862 |
0,18944307 |
0,25259075 |
| 2 |
1,7320508 |
1,0825318 |
0,649519 |
0,4330128 |
0,21650636 |
0,28867513 |
| 2,5 |
2,1650635 |
1,35316475 |
0,81189875 |
0,541266 |
0,27063295 |
0,36084392 |
| 3 |
2,5980762 |
1,6237977 |
0,9742785 |
0,6495192 |
0,32475954 |
0,4330127 |
| 3,5 |
3,0310889 |
1,89443065 |
1,13665825 |
0,7577724 |
0,37888613 |
0,50518148 |
| 4 |
3,4641016 |
2,1650636 |
1,299038 |
0,8660256 |
0,43301272 |
0,57735027 |
| 4,5 |
3,8971143 |
2,43569655 |
1,46141775 |
0,9742788 |
0,48713931 |
0,64951905 |
| 5 |
4,330127 |
2,7063295 |
1,6237975 |
1,082532 |
0,5412659 |
0,72168783 |
| 5,5 |
4,7631397 |
2,97696245 |
1,78617725 |
1,1907852 |
0,59539249 |
0,79385662 |
| 6 |
5,1961524 |
3,2475954 |
1,948557 |
1,2990384 |
0,64951908 |
0,8660254 |
| 8 |
6,9282032 |
4,3301272 |
2,598076 |
1,7320512 |
0,86602544 |
1,15470053 |
Basic Screw Dimensions
From these basic proportions it is very easy to obtain the basic
thread dimensions a typical set of ISO metric coarse threads are identified with the
basic dimensions as shown below
Table showing dimensions of some typical ISO metric coarse threads
| Thread |
Pitch |
Major |
Pitch Dia |
Minor |
|
Thread |
Pitch |
Major |
Pitch Dia |
Minor |
| P |
D/d |
D2 /d 2 |
D1 /d 1 |
P |
D/d |
D2 /d 2 |
D1 /d 1 |
| mm |
mm |
mm |
mm |
mm |
mm |
mm |
mm |
| M3 x 0,5 |
0,5 |
3,000 |
2,675 |
2,459 |
M12x1,75 |
1,7 |
12,000 |
10,863 |
10,106 |
| M4 x 0,7 |
0,7 |
4,000 |
3,545 |
3,242 |
M16 x 2,0 |
2 |
16,000 |
14,701 |
13,835 |
| M5 x 0,8 |
0,8 |
5,000 |
4,48 |
4,134 |
M20 x2,5 |
2,5 |
20,000 |
18,376 |
17,294 |
| M6 x 1,0 |
1 |
6,000 |
5,35 |
4,917 |
M24 x 3,0 |
3 |
24,000 |
22,051 |
20,752 |
| M8 x 1,25 |
1,25 |
8,000 |
7,188 |
6,647 |
M30 x 3,5 |
3,5 |
30,000 |
27,727 |
26,211 |
| M10 x 1,5 |
1,5 |
10,000 |
9,026 |
8,376 |
M36 x 4,0 |
4 |
36,000 |
33,402 |
31,67 |
Screw Pitch
There are a number of pitch values for each screw diameter.
The selection as to the pitch is based on the application. The largest
pitch option for diameters M1 to M64 is identified as the coarse pitch and is
to one used for general engineering applications. A table of the coarse pitch
series is provided below. Other pitch values for each diameter are called
the fine series or constant series.
| M1 x 0,25 | M1,2 x 0,25 | M1,4 x 0,30 | M1,6 x 0,35 |
M1,8 x 0,35 | M2 x 0,4 | M2,2 x 0,45 |
| M2,5 x 0,45 | M2,5 x 0,45 | M3 x 0,5 | M3,5 x 0,6 |
M4 x 0,7 | M4,5 x 0,75 | M5 x 0,8 |
| M6 x 1 | M7 x 1 | M8 x1,25 | M9 x1,25 |
M10 x 1,5 | M11 x 1,5 | M12 x 1,75 |
| M14 x 2,0 | M16 x 2 | M18 x 2,5 | M20 x 2,5 |
M22 x 2,5 | M24 x 3,0 | M27 x 3 |
| M30 x 3,5 | M33 x 3,5 | M36 x 4 | M39 x 4 |
M42 x 4,5 | M45 x 5 | M48 x5 |
| M52 x 5 | M56 x5,5 | M60 x 5,5 |
M64 x 6 | M68 x 6 |
Fine series threads are only listed in the standards up to M33.
The name fine does not imply higher quality. The fine series are listed below.
| M1 / M1,1/ M1,2 / M1,4 / M1,6 / M1,8 (x 0,2) | M2 / M2,2 (x 0,25) | M2,5 / M3 / M3,5 (x 0,35) |
| M4 / M4,5 / M5,5 (x 0,5) | M6 / M7( x 0,75) | M8 x 1 |
| M10 / 12 (x 1,25) | M14 / M16 / M18 / M20 / M22 (x 1,5) | M24 / M25 / M27/ M30 / M33 (x 2) |
The constant thread series are identified in the standards for
the screw range M8 upwards and are normally those pitches not classed as coarse or fine
Tolerances for External (screws) and Internal (Nuts) Threads
The method of applying manufacturing tolerances to the female and male
threads such that they fit together is by use of the tolerance class which is a combination
of the tolerance grade ( a number) and a tolerance position ( a letter).
For the female threads the letter is upper class and for the male threads the letter is lower class.
Therefore H6 is a tolerance grade for a female ( Internal ) thread and g6 is a tolerance grade
for a male (External ) thread.
The tolerance band positions relative to the basic zero size are illustrated in the
figure below
The (fundamental)tolerance position is defined as the nearest end of the tolerance band
to the zero tolerance position (Dead size position). These positions are identified
as EI for the female thread and es for the male thread.
There are a limited number of tolerance grades used to specify threads and the standards
identify these grades for the Minor ( D1 ) and Pitch ( D2 )diameters
of the female threads and the Major ( d ) and Pitch ( d2 ) diameters of
the male threads. Tolerance grades are not provided for none critical
female major dia (D) and the male minor diameter (d3). The
numbers of grades used are listed below.
D1 : tolerance grades 4,5,6,7 & 8
d : tolerance grades 4,6, & 8
D2 tolerance grades 4,5,6,7 & 8
d2 tolerance grades 3,4,5,6,8 & 9
The tolerance positions available are EI = G & H for female threads
and es = e,f g, or h for male threads.
Selection of tolerance classes
To simplify the selection of the tolerance classes threads have been divide
into three categories.
Fine ... For precision threads
Medium ...For general industrial use
Coarse .. For rough manufacture threads
The length of thread engagement is also used as a parameter for selection of the tolerance class
The following tables identifies the range of tolerance classes and the length of screws for selecting the length parameter.
Table showing tolerance classes
| Female Threads |
Class
v | Tolerance Position G | Tolerance Position H |
| Short | Normal | Long | Short | Normal | long |
| Fine | - | - | - |
4H | 5H |
6H |
| Medium |
5G | 6G | 7G |
5H | 6H |
7H |
| Rough | - | 7G |
8G | - | 7H | 8H |
| Male Threads |
Class
v | Tolerance Position e |
Tolerance Position f |
Tolerance Position g | Tolerance Position h |
| Short | Normal | Long |
Short | Normal | Long |
Short | Normal | Long | Short |
Normal | Long |
| Fine | | | |
| | | | |
| 3h4h | 4h | 5h4h |
| Medium | | 6e | 7e6e | |
6f | | 5g6g |
6g | 7g6g | 5h6h |
6h | 7h6h |
| Rough | | | | | | | |
8g | 9g8g | | | |
....First Choice
....Second Choice
... Commercial Nuts /Bolt Threads
... Third choice to be avoided
Note:
When two shaft tolerance grades are shown the first is for the pitch dia
and the second is for the major diameter.
When only one is shown it is the same for both
diameters.
Table For Selecting Screw Length Parameter
| Basic Major Dia |
Pitch |
Length of Thread Engagement |
| Short |
Normal |
Long |
| over |
Up to +(inc) |
Up to + (Inc) |
Over |
Up to + (Inc) |
Over |
| mm |
mm |
mm |
mm |
mm |
mm |
mm |
| 0,99 |
1,4 |
0,2 |
0,5 |
0,5 |
1,4 |
1,4 |
| 0,25 |
0,6 |
0,6 |
1,7 |
1,7 |
| 0,3 |
0,7 |
0,7 |
2,0 |
2,0 |
| 1,4 |
2,8 |
0,2 |
0,5 |
0,5 |
1,5 |
1,5 |
| 0,25 |
0,6 |
0,6 |
1,9 |
1,9 |
| 0,35 |
0,8 |
0,8 |
2,6 |
2,6 |
| 0,4 |
1,0 |
1,0 |
3,0 |
3,0 |
| 0,45 |
1,3 |
1,3 |
3,8 |
3,8 |
| 2,8 |
5,6 |
0,35 |
1,0 |
1,0 |
3,0 |
3,0 |
| 0,5 |
1,5 |
1,5 |
4,5 |
4,5 |
| 0,6 |
1,7 |
1,7 |
5,0 |
5,0 |
| 0,7 |
2 |
2 |
6 |
6 |
| 0,75 |
2,2 |
2,2 |
6,7 |
6,7 |
| 0,8 |
2,5 |
2,5 |
7,5 |
7,5 |
| 5,6 |
11,2 |
0,75 |
2,4 |
2,4 |
7,1 |
7,1 |
| 1,0 |
3 |
3 |
9 |
9 |
| 1,25 |
4 |
4 |
12 |
12 |
| 1,5 |
5 |
5 |
15 |
15 |
| 11,2 |
22,4 |
1,0 |
3,8 |
3,8 |
11 |
11 |
| 1,25 |
4,5 |
4,5 |
13 |
13 |
| 1,5 |
5,6 |
5,6 |
16 |
16 |
| 1,75 |
6 |
6 |
18 |
18 |
| 2,0 |
8 |
8 |
24 |
24 |
| 2,5 |
10 |
10 |
30 |
30 |
| 22,4 |
45,0 |
1,0 |
4 |
4 |
12 |
12 |
| 1,5 |
6,3 |
6,3 |
19 |
19 |
| 2,0 |
8,5 |
8,5 |
25 |
25 |
| 3,0 |
12 |
12 |
36 |
36 |
| 3,5 |
15 |
15 |
45 |
45 |
| 4,0 |
18 |
18 |
53 |
53 |
| 4,5 |
21 |
21 |
63 |
63 |
| 45,0 |
90,0 |
1,5 |
7,5 |
7,5 |
22 |
22 |
| 2,0 |
9,5 |
9,5 |
28 |
28 |
| 3,0 |
15 |
15 |
45 |
45 |
| 4,0 |
19 |
19 |
56 |
56 |
| 5,0 |
24 |
24 |
71 |
71 |
| 5,5 |
28 |
28 |
85 |
85 |
| 6,0 |
32 |
32 |
95 |
95 |
| 90,0 |
180,0 |
2,0 |
12 |
12 |
36 |
36 |
| 3,0 |
18 |
18 |
53 |
53 |
| 4,0 |
24 |
24 |
71 |
71 |
| 6,0 |
36 |
36 |
106 |
106 |
| 180,0 |
300 |
3,0 |
20 |
20 |
60 |
60 |
| 4,0 |
26 |
26 |
80 |
80 |
| 5,0 |
40 |
40 |
118 |
118 |
Table relating Fundamental deviation EI and es to Pitch
| Pitch |
Female Thread D2,D1 |
Male Thread d,d2 |
|
Pitch |
Female Thread D2,D1 |
Male Thread d,d2 |
| EI |
es |
EI |
es |
| G |
H |
e |
f |
g |
h |
G |
H |
e |
f |
g |
h |
| mm |
μm |
μm |
μm |
μm |
μm |
μm |
mm |
μm |
μm |
μm |
μm |
μm |
μm |
| 0,2 |
+17 |
0 |
- |
- |
-17 |
0 |
1,25 |
+28 |
0 |
-63 |
-42 |
-28 |
0 |
| 0,25 |
+18 |
0 |
- |
- |
-18 |
0 |
1,5 |
+32 |
0 |
-67 |
-45 |
-32 |
0 |
| 0,3 |
+18 |
0 |
- |
- |
-18 |
0 |
1,75 |
+34 |
0 |
-71 |
-48 |
-34 |
0 |
| 0,35 |
+19 |
0 |
- |
-34 |
-19 |
0 |
2,0 |
+38 |
0 |
-71 |
-52 |
-38 |
0 |
| 0,4 |
+19 |
0 |
- |
-34 |
-19 |
0 |
2,5 |
+42 |
0 |
-80 |
-58 |
-42 |
0 |
| 0,45 |
+20 |
0 |
- |
-35 |
-20 |
0 |
3,0 |
+48 |
0 |
-85 |
-63 |
-48 |
0 |
| 0,5 |
+20 |
0 |
-50 |
-36 |
-20 |
0 |
3,5 |
+53 |
0 |
-90 |
-70 |
-53 |
0 |
| 0,6 |
+21 |
0 |
-53 |
-36 |
-21 |
0 |
4,0 |
+60 |
0 |
-95 |
-75 |
-60 |
0 |
| 0,7 |
+22 |
0 |
-56 |
-38 |
-22 |
0 |
4,5 |
+63 |
0 |
-100 |
-80 |
-63 |
0 |
| 0,75 |
+22 |
0 |
-56 |
-38 |
-22 |
0 |
5,0 |
+71 |
0 |
-106 |
-85 |
-71 |
0 |
| 0,8 |
+24 |
0 |
-60 |
-38 |
-24 |
0 |
5,5 |
+75 |
0 |
-112 |
-90 |
-75 |
0 |
| 1,0 |
+26 |
0 |
-60 |
-40 |
-26 |
0 |
6,0 |
+80 |
0 |
-118 |
-95 |
-80 |
0 |
| |
|
|
|
|
|
|
8,0 |
+100 |
0 |
-140 |
-118 |
-100 |
0 |
Table of T tolerance widths. (Pitch Diameters )
For Finished uncoated threads.
| D2 /d2 |
Pitch |
|
Pitch Diameter of internal threads |
|
Pitch diameter of external threads |
| Over |
To(&inc) |
T:4 |
T:5 |
T:6 |
T:7 |
T:8 |
T:3 |
T:4 |
T:5 |
T:6 |
T:7 |
T:8 |
T:9 |
| mm |
mm |
mm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
| 0,99 |
1,4 |
0,2 |
40 |
- |
- |
|
|
24 |
30 |
48 |
48 |
|
|
|
| |
|
0,25 |
45 |
56 |
- |
|
|
25 |
34 |
42 |
53 |
|
|
|
| |
|
0,3 |
48 |
60 |
75 |
|
|
28 |
36 |
45 |
56 |
|
|
|
| 1,4 |
2,8 |
0,2 |
42 |
|
|
|
|
25 |
32 |
40 |
50 |
|
|
|
| |
|
0,25 |
48 |
60 |
|
|
|
28 |
36 |
45 |
56 |
|
|
|
| |
|
0,35 |
53 |
67 |
85 |
|
|
32 |
40 |
50 |
63 |
80 |
|
|
| |
|
0,4 |
56 |
71 |
90 |
|
|
34 |
42 |
53 |
67 |
85 |
|
|
| |
|
0,45 |
60 |
75 |
95 |
|
|
36 |
45 |
56 |
71 |
90 |
|
|
| 2,8 |
5,6 |
0,35 |
56 |
71 |
90 |
|
|
34 |
52 |
53 |
67 |
85 |
|
|
| |
|
0,5 |
63 |
80 |
100 |
125 |
|
38 |
48 |
60 |
75 |
95 |
|
|
| |
|
0,6 |
71 |
90 |
112 |
140 |
|
42 |
53 |
67 |
85 |
106 |
|
|
| |
|
0,7 |
75 |
95 |
118 |
150 |
|
45 |
56 |
71 |
90 |
112 |
|
|
| |
|
0,75 |
75 |
95 |
118 |
150 |
|
45 |
56 |
71 |
90 |
112 |
|
|
| |
|
0,8 |
80 |
100 |
125 |
160 |
200 |
48 |
60 |
75 |
95 |
118 |
150 |
90 |
| 5.6 |
11,2 |
0,75 |
85 |
106 |
132 |
170 |
|
50 |
63 |
80 |
100 |
125 |
|
|
| |
|
1 |
95 |
118 |
140 |
190 |
236 |
56 |
71 |
90 |
112 |
140 |
180 |
224 |
| |
|
1,25 |
100 |
125 |
160 |
200 |
250 |
60 |
75 |
95 |
118 |
150 |
189 |
235 |
| |
|
1,5 |
112 |
140 |
180 |
224 |
280 |
67 |
85 |
106 |
132 |
170 |
212 |
265 |
| 11,2 |
22,4 |
1 |
100 |
125 |
160 |
200 |
250 |
60 |
75 |
95 |
118 |
150 |
190 |
235 |
| |
|
1,25 |
112 |
140 |
180 |
224 |
280 |
67 |
85 |
106 |
132 |
170 |
212 |
265 |
| |
|
1,4 |
118 |
150 |
190 |
236 |
300 |
71 |
90 |
112 |
140 |
180 |
224 |
280 |
| |
|
1,75 |
125 |
160 |
200 |
250 |
315 |
75 |
95 |
118 |
150 |
190 |
236 |
300 |
| |
|
2,0 |
132 |
170 |
212 |
265 |
335 |
80 |
100 |
125 |
160 |
200 |
250 |
315 |
| |
|
2,5 |
140 |
180 |
224 |
280 |
355 |
85 |
106 |
132 |
170 |
212 |
265 |
335 |
| 22,4 |
45 |
1 |
106 |
132 |
170 |
212 |
|
63 |
80 |
100 |
125 |
160 |
200 |
250 |
| |
|
1,5 |
125 |
160 |
200 |
250 |
315 |
75 |
95 |
118 |
150 |
190 |
236 |
300 |
| |
|
2 |
140 |
180 |
224 |
280 |
355 |
85 |
106 |
132 |
170 |
212 |
265 |
335 |
| |
|
3 |
170 |
212 |
265 |
335 |
425 |
100 |
125 |
160 |
200 |
250 |
315 |
400 |
| |
|
3,5 |
180 |
224 |
280 |
355 |
450 |
106 |
132 |
170 |
212 |
265 |
335 |
425 |
| |
|
4 |
190 |
236 |
300 |
375 |
475 |
112 |
140 |
180 |
224 |
280 |
355 |
450 |
| |
|
4,5 |
200 |
250 |
315 |
400 |
500 |
118 |
150 |
190 |
236 |
300 |
375 |
475 |
| 45 |
90 |
1,5 |
132 |
170 |
212 |
265 |
335 |
80 |
100 |
125 |
160 |
200 |
250 |
315 |
| |
|
2 |
150 |
190 |
236 |
300 |
375 |
90 |
112 |
140 |
180 |
224 |
280 |
355 |
| |
|
3 |
180 |
224 |
280 |
355 |
450 |
106 |
132 |
170 |
212 |
265 |
335 |
425 |
| |
|
4 |
200 |
250 |
315 |
400 |
500 |
118 |
150 |
190 |
236 |
300 |
375 |
475 |
| |
|
5 |
212 |
265 |
335 |
425 |
530 |
125 |
160 |
200 |
250 |
315 |
400 |
500 |
| |
|
5,5 |
224 |
280 |
355 |
450 |
560 |
132 |
170 |
212 |
265 |
335 |
425 |
530 |
| |
|
6 |
236 |
300 |
375 |
475 |
600 |
140 |
180 |
224 |
280 |
355 |
450 |
560 |
| 90 |
180 |
2 |
160 |
200 |
250 |
315 |
400 |
95 |
118 |
150 |
190 |
236 |
300 |
375 |
| |
|
3 |
190 |
236 |
300 |
375 |
475 |
112 |
140 |
180 |
224 |
280 |
355 |
450 |
| |
|
4 |
212 |
265 |
335 |
425 |
530 |
125 |
160 |
200 |
250 |
315 |
400 |
500 |
| |
|
6 |
250 |
315 |
400 |
500 |
630 |
150 |
190 |
236 |
300 |
375 |
475 |
600 |
| |
|
8 |
280 |
355 |
450 |
560 |
710 |
175 |
212 |
265 |
335 |
425 |
530 |
670 |
| 180 |
355 |
3 |
212 |
265 |
335 |
425 |
530 |
125 |
160 |
200 |
250 |
315 |
400 |
500 |
| |
|
4 |
236 |
300 |
375 |
475 |
60 |
140 |
180 |
224 |
280 |
355 |
450 |
560 |
| |
|
6 |
265 |
335 |
425 |
530 |
670 |
160 |
200 |
250 |
315 |
400 |
500 |
630 |
| |
|
8 |
300 |
375 |
475 |
600 |
750 |
180 |
224 |
280 |
355 |
450 |
560 |
710 |
| Over |
To(&inc) |
Pitch |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
μm |
| D2 /d2 |
T:4 |
T:5 |
T:6 |
T:7 |
T:8 |
T:3 |
T:4 |
T:5 |
T:6 |
T:7 |
T:8 |
T:9 |
|
Pitch Diameter of internal threads |
Pitch diameter of external threads |
Table of T tolerance widths. (Major (Male) and Minor Diameters (Female)
For Finished uncoated threads.
| Pitch |
|
Major Dia -Male threads |
|
Minor Diameter - Female Threads |
T:4 |
T:6 |
T:8 |
T:4 |
T:5 |
T:6 |
T:7 |
T:8 |
| mm |
μm |
μm |
μm |
μm |
μm |
μm |
μm; |
μm |
| 0,2 |
36 |
56 |
|
38 |
|
|
|
|
| 0,25 |
42 |
67 |
|
45 |
56 |
|
|
|
| 0,3 |
48 |
75 |
|
53 |
67 |
85 |
|
|
| 0,35 |
53 |
85 |
|
63 |
80 |
100 |
|
|
| 0,4 |
60 |
95 |
|
71 |
90 |
112 |
|
|
| 0,45 |
63 |
100 |
|
80 |
100 |
125 |
|
|
| 0,5 |
67 |
106 |
|
90 |
112 |
140 |
180 |
|
| 0,6 |
80 |
125 |
|
100 |
125 |
160 |
200 |
|
| 0,7 |
90 |
140 |
|
112 |
140 |
180 |
224 |
|
| 0,75 |
90 |
140 |
|
118 |
150 |
190 |
236 |
|
| 0,8 |
95 |
150 |
236 |
125 |
160 |
200 |
250 |
315 |
| 1,0 |
112 |
180 |
280 |
150 |
190 |
236 |
300 |
375 |
| 1,25 |
132 |
212 |
335 |
170 |
212 |
265 |
335 |
425 |
| 1,5 |
150 |
236 |
375 |
190 |
236 |
300 |
375 |
475 |
| 1,75 |
170 |
265 |
425 |
212 |
236 |
335 |
425 |
530 |
| 2,0 |
180 |
280 |
450 |
236 |
300 |
375 |
475 |
600 |
| 2,5 |
212 |
335 |
530 |
280 |
355 |
450 |
560 |
710 |
| 3,0 |
236 |
375 |
600 |
315 |
400 |
500 |
630 |
800 |
| 3,5 |
265 |
425 |
670 |
355 |
450 |
560 |
710 |
900 |
| 4,0 |
300 |
475 |
750 |
375 |
475 |
600 |
750 |
950 |
| 4,5 |
315 |
500 |
800 |
425 |
530 |
670 |
850 |
1060 |
| 5,0 |
335 |
530 |
850 |
450 |
560 |
710 |
900 |
1120 |
| 5,5 |
355 |
560 |
900 |
475 |
600 |
750 |
950 |
1180 |
| 6,0 |
375 |
600 |
950 |
500 |
630 |
800 |
1000 |
1250 |
| 8,0 |
450 |
710 |
1180 |
630 |
800 |
1000 |
1250 |
1600 |
| mm |
μm |
μm |
μm |
μm |
μm |
μm |
μm; |
μm |
| Pitch |
T:4 |
T:6 |
T:8 |
T:4 |
T:5 |
T:6 |
T:7 |
T:8 |
| Major Dia -Male threads |
Minor Diameter - Female Threads |
Root Contours
For both internal and external threads the actual root contours shall not
transgress the basic profile.
Note: In accordance with the requirements of BS EN ISO 898-1
for external fasteners of property class 8,8 and higher the root profile shall
have non-reversing curvature, no part of the profile shall have a radius of
less than 0,125P. It is advisable to attempt a truncation of C = H/6 as
a basis for stress calculation of the minor dia d3
In the maximum minor position d 3min the two radii of Rmin = 0,125P will go through
the corners of the no-go gauge profile and blend with the flanks of the maximum metal
condition thread form.(see figure below)
The maximum truncation Cmaxis calculated using the following equation
Cmin = 0,125P
To calculate d3min first obtain z
d3min = d1 - es -2z
To calculate d3max first obtain y
d3max = d1 - es - 2y
Examples
Male Threads
| Name |
Equation |
Identity |
Values |
| Designation |
|
|
M30 x 3,5 - 6g |
M12 x 1,25 -4h |
M150 x 4 - 6e |
M200 x 6 - 4g |
| Diameter |
d |
d |
30 |
12 |
150 |
200 |
| Pitch |
P |
P |
3,5 |
1,25 |
4 |
6 |
| Basic Pitch Dia |
d2 =d-0,68952P |
d2 |
27,727 |
11,188 |
147,402 |
196,103 |
| Basic Minor Dia |
d1=d-1,08254,P |
d1 |
26,211 |
10,647 |
145,67 |
193,505 |
| Fundamental Deviation |
es |
es |
0,053 |
0 |
0,095 |
0,08 |
| Tolerance Width diameter (d) |
Td |
Td |
0,425 |
0,132 |
0,375 |
0,6 |
| Tolerance Width Pitch dia,d 2 |
Td2 |
Td2 |
0,212 |
0,085 |
0,19 |
0,315 |
| Extreme Deviation d |
eid = es+Td |
eid |
0,478 |
0,132 |
0,47 |
0,68 |
| Extreme Deviation d 2 |
eid2 = es+Td2 |
eid2 |
0,265 |
0,085 |
0,085 |
0,085 |
| Rmin |
Rmin = 0,125P |
Rmin |
0,438 |
0,156 |
0,5 |
0,75 |
| z |
See above |
|
0,426 |
0,157 |
0,461 |
0,707 |
| y |
See above |
|
0,064 |
0,021 |
0,09 |
0,125 |
| |
|
|
|
|
|
|
| Major Dia (max) |
dmin = d + es |
dmin |
29,947 |
12 |
149,905 |
199,92 |
| Major Dia (max) |
dmax=d+ eid |
dmax |
29,522 |
11,868 |
149,53 |
199,32 |
| Pitch Dia (max) |
d2min = d2+es |
d2min |
27,674 |
11,188 |
147,307 |
196,023 |
| Pitch Dia (min) |
d2max=d2+eid2 |
d2max |
27,462 |
11,103 |
147,317 |
196,018 |
| Minor Dia (min) |
d3min =d1-es-2z |
d3min |
25,306 |
10,333 |
144,653 |
192,012 |
| Minor Dia (max) |
d3max = d1-es-2y |
d3max |
26,029 |
10,606 |
145,396 |
193,175 |
Female Threads
| Name |
Equation |
Identity |
Values |
| |
|
|
M30 x 3,5 -6H |
M12 x1,25 - 7H |
M150 x 4 - 6G |
M200 x 6 x 5H |
| Diameter |
D |
D |
30 |
12 |
150 |
200 |
| Pitch |
P |
P |
3,5 |
1,25 |
4 |
6 |
| Basic Pitch Dia |
D2 = D-0,68952P |
D2 |
27,727 |
11,188 |
147,402 |
196,103 |
| Basic Minor Diameter |
D1=D-1,08254,P |
D1 |
26,211 |
10,647 |
145,67 |
193,505 |
| Fundamental Deviation |
EI |
EI |
0 |
0 |
0,06 |
0 |
| Tolerance Width diameter (d) |
T |
T |
0 |
0 |
0 |
0 |
| Tolerance Width Pitch diameter (D2) |
TD2 |
TD2 |
0,28 |
0,224 |
0,335 |
0,335 |
| Tolerance Width Minor Dia(D1) |
TD1 |
TD1 |
0,56 |
0,335 |
0,6 |
0,63 |
| Extreme Deviation (D2) |
ESD2 = EI+TD2 |
ESD2 |
0,28 |
0,224 |
0,395 |
0,335 |
| Extreme Deviation (D1) |
ESD1 = EI+TD1/ |
ESD1 |
0,56 |
0,335 |
0,66 |
0,63 |
| |
|
|
|
|
|
|
| Major Di (min) |
Dmin |
Dmin |
30 |
12 |
150 |
200 |
| Pitch Dia (min) |
D2min = D2+EI |
D2min |
27,727 |
11,188 |
147,462 |
196,103 |
| Pitch Dia (max) |
D2max=D2+ ESD2 |
D2max |
28,007 |
11,412 |
147,797 |
196,438 |
| Minor Dia (min) |
D1min = D1+EI |
D1min |
26,211 |
10,647 |
145,73 |
193,505 |
| Minor Dia (max) |
D1max=D1+ ESD1 |
D1max |
26,771 |
10,982 |
146,33 |
194,135 |
|