All information provided below is for guidance only and should not be used when working to stringent specifications.

Whitworth & BSF Hexagons BS 1083

Diameter 1/4″ 5/16″ 3/8″ 1/2″ 5/8″ 3/4″ 7/8″ 1″
T.P.I. Whitworth
BSF 		20
26 		18
22 		16
20 		12
16 		11
14 		10
12 		9
11 		8
10
Hexagon A/F 0.438
0.445 		0.518
0.525 		0.592
0.600 		0.812
0.820 		1.000
1.010 		1.190
1.200 		1.288
1.300 		1.468
1.480
Hexagon Depth 0.166
0.176 		0.208
0.218 		0.250
0.260 		0.333
0.343 		0.407
0.417 		0.480
0.500 		0.563
0.583 		0.636
0.666
Full Nut Depth 0.190
0.200 		0.240
0.250 		0.302
0.312 		0.427
0.437 		0.552
0.562 		0.677
0.687 		0.740
0.750 		0.865
0.875
Lock Nut Depth 0.123
0.133 		0.156
0.166 		0.198
0.208 		0.281
0.291 		0.365
0.375 		0.448
0.458 		0.490
0.500 		0.573
0.583

Whitworth & BSF Screws BS450 & Nuts BS 1803

Diameter 1/8″ 5/32″ 3/16″ 1/4″ 5/16″ 3/8″
T. P. I. Whitworth
BSF 		40
N/A 		32
N/A 		24
32 		20
26 		18
22 		16
20
CSK Head Dia. 0.201
0.219 		0.254
0.273 		0.307
0.328 		0.412
0.438 		0.518
0.547 		0.624
0.656
CSK Head Depth 0.056
 0.070
 0.084
 0.113
 0.141
 0.169
Rd. Head. Dia. 0.206
0.219 		0.259
0.273 		0.312
0.328 		0.417
0.438 		0.524
0.547 		0.629
0.656
Rd. Head. Depth 0.082
0.087 		0.103
0.109 		0.124
0.131 		0.165
0.175 		0.207
0.219 		0.249
0.262
Ch. Head. Dia. 0.180
0.188 		0.225
0.234 		0.270
0.281 		0.360
0.375 		0.450
0.469 		0.540
0.562
Ch. Head. Depth 0.082
0.087 		0.103
0.109 		0.124
0.131 		0.165
0.175 		0.207
0.219 		0.249
0.262
Inst. Head. Dia. 0.201
0.219 		0.254
0.273 		0.307
0.328 		0.412
0.438 		0.518
0.547 		0.624
0.656
Inst. Head. Depth 0.082 0.103 0.124 0.164 0.209 0.249
Nut. A/F 0.216
0.220 		0.243
0.248 		0.319
0.324 		0.438
0.445 		0.518
0.525 		0.592
0.600
Nut Depth
0.115
0.130
0.162 		0.190
0.200 		0.240
0.250 		0.302
0.312

Unified Hexagons

Diameter 1/4″ 5/16″ 3/8″ 1/2″ 5/8″ 3/4″ 7/8″ 1″
T.P.I. UNC
UNF 		20
28 		18
24 		16
24 		13
20 		11
18 		10
16 		9
14 		8
12
Hexagon A/F 0.430
0.437 		0.493 0.554
0.562 		0.742
0.750 		0.929
0.937 		1.115
1.125 		1.300
1.312 		1.488
1.500
Hexagon Depth 0.153
0.163 		0.201
0.211 		0.233
0.243 		0.313
0.323 		0.393
0.403 		0.463
0.483 		0.543
0.563 		0.597
0.627
Full Nut Depth 0.214
0.224 		0.261
0.271 		0.323
0.333 		0.432
O.442 		0.542
0.552 		0.631
0.651 		0.740
0.760 		0.844
0.874
Lock Nut Depth 0.151
0.161 		0.182
0.192 		0.214
0.224 		0.307
0.317 		0.370
0.380 		0.412 0.474
0.494 		0.532
0.562

Unified Screws & Nuts

Diameter No. O No. 2 No. 4 No. 6 No. 8 No. 10 1/4″ 5/16″ 3/8″
T.P.I. UNC
UNF 		–
80 		56
– 		40
– 		32
– 		32
– 		24
32 		20
28 		18
24 		16
24
CSK. Head Dia. 0.099
0.119 		0.147
0.172 		0.195
0.225 		O.244
0.279 		0.292
0.332 		0.340
0.365 		0.452
0.507 		0.568
0.635 		0.685
0.762
CSK. Head Depth 0.035 0.051 0.067 0.083 0.116 0.153 0.191 0.230
Pan Head Dia. 0.104
0.116 		0.155
0.162 		0.205
0.219 		0.256
0.270 		0.306
0.322 		0.357
0.373 		0.473
0.492 		0.594
0.615 		0.716
0.740
Pan Head Depth 0.031
0.039 		0.045
0.053 		0.058
0.068 		0.072
0.082 		0.085
0.096 		0.099
0.110 		0.130
0.144 		0.162
0.178 		0.195
0.212
Fillister Head Dia. 0.083
0.096 		0.124
0.140 		0.166
0.183 		0.208
0.226 		0.250
0.270 		0.292
0.313 		0.389
0.414 		0.490
0.518 		0.590
0.622
Fillister Head Depth 0.043
0.059 		0.066
0.083 		0.088
0.107 		0.111
0.132 		0.133
0.156 		0.156
0.180 		0.207
0.237 		0.262
0.295 		0.315
0.355
Nut A/F 0.150
0.156 		0.180
0.187 		0.241
0.250 		0.302
0.312 		0.332
0.343 		0.362
0.375 		0.430
0.437 		0.493
0.500 		0.554
0.562
Nut Depth 0.043
0.050 		0.057
0.066 		0.087
0.098 		0.102
0.114 		0.117
0.130 		0.117
0.130 		0.214
0.224 		0.261
0.271 		0.323
0.333

Stainless Steels

Chemical Composition

Carbon Silicon Manganese Phosphorus Sulphur Chromium Nickel Molybdenum
AUSTENITIC
A1. Free machining steel. Perhaps not as corrosion resistant as other austenitic?s. Non-magnetic.
0.12
1.0
2.0
0.20
0.15/0.35
17/19
8/10
0.60
A2. Satisfactory ability to resist some mild acid but not hydrochloric. Non-magnetic unless heavily cold worked.
0.08
1.0
2.0
0.05
0.03
17/20
8/13
–
A3. Greater corrosion resistance than the above. Recommended for marine use. Non-magnetic unless heavily cold worked
0.08
1.0
2.0
0.05
0.03
16/18.5
10/14
2/3
MARTENSITIC
C3.Widely used in Aircraft industry. Higher tensile strength than austenitic. Good wear resistant surface. Less corrosion resistant than austenitics. Magnetic.
0.17/0.25
1.0
1.0
0.04
0.03
16/18
1.5/2.5
–

Austenitic Stainless Steels

Mechanical Properties

Property Class
Diameter Range
Tensile
Strength
N/mm
Elongation
Yield Stress
N/mm2
0.2% Permanent Strain
50
Up to M39
500
0.6d
210
70
Up to M20
700
0.4d
450
80
Up to M20
800
0.3d
600

All property values are determined on finished products – not on machined test pieces.
All tensile stress values are calculated in terms of the nominal (mean) tensile stress area of the thread.
Yield stress is defined as the stress to give 0.2% permanent strain
Total elongation is the increase in total length at fracture after tensile loading expressed as a factor of the thread diameter. d equals nominal diameter of the thread.
Above M20 the higher strength property classes should have the property values specifically agreed upon between user and manufacturer because of the tensile strength factors given, alternative values of stress at 0.2% permanent strain may occur.