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    2. ASME B18.3 Flat Head Socket Screws Dimensions

    ASME B18.3 Flat Head Socket Screws Dimensions

    Countersunk socket screws for flush surface installation and clean finishes

    ASME B18.3 Flat Head Socket Screws Dimension Standard include countersunk head angles and specifications for flush mounting applications.

    ASME B18.3 Hexagon Socket Flat Countersunk Head Cap Screws

    ASME B18.3 Flat Head Socket Screws Dimension (mm)

    Nominal Size Body Diameter, D Head Diameter, A Reference Head Height, H Protrusion Gage Diameter, G Protrusion, P Nominal Hexagon Socket Size, J Minimum Key Engagement, T Maximum Fillet Transition Diameter, F
    Max. Min. Max. Min. Max. Min. Max. Min. Min. Max.
    0 (0.0600) 1.524 1.442 3.505 2.971 1.117 1.981 1.955 1.117 0.660 0.902 0.889 0.635 1.828
    1 (0.0730) 1.854 1.765 4.267 3.632 1.371 2.565 2.540 1.219 0.711 1.295 1.270 0.787 2.260
    2 (0.0860) 2.184 2.087 5.003 4.267 1.625 3.149 3.124 1.295 0.787 1.295 1.270 0.965 2.692
    3 (0.0990) 2.514 2.410 5.740 4.902 1.854 3.759 3.733 1.371 0.838 1.613 1.588 1.117 3.022
    4 (0.1120) 2.844 2.730 6.477 5.537 2.108 4.368 4.343 1.447 0.914 1.613 1.588 1.397 3.454
    5 (0.1250) 3.175 3.053 7.137 6.096 2.286 4.978 4.953 1.498 0.939 2.009 1.984 1.549 3.886
    6 (0.1380) 3.505 3.375 7.797 6.680 2.463 5.588 5.562 1.524 0.939 2.009 1.984 1.676 4.267
    8 (0.1640) 4.165 4.025 9.118 7.899 2.844 6.781 6.756 1.600 0.990 2.418 2.38 1.930 4.927
    10 (0.1900) 4.826 4.673 10.439 9.118 3.225 7.950 7.924 1.676 1.041 3.226 3.175 2.209 5.588
    12 (0.2158) 5.481 5.339 11.430 10.414 3.429 9.144 9.118 1.752 1.066 3.226 3.175 2.387 6.248
    1/4 (0.2500) 6.350 6.184 13.487 12.192 4.089 10.769 10.744 1.828 1.092 4.031 3.967 2.819 7.112
    5/16 (0.3125) 7.937 7.747 16.662 15.240 5.029 13.690 13.665 1.981 1.193 4.826 4.763 3.429 8.712
    3/8 (0.3750) 9.525 9.342 19.837 18.288 5.943 16.586 16.560 2.235 1.270 5.631 5.555 4.038 10.287
    7/16 (0.4375) 11.112 10.906 21.437 19.837 5.943 17.526 17.475 2.641 1.600 6.426 6.35 4.038 11.887
    1/2 (0.5000) 12.700 12.494 23.825 22.148 6.375 18.770 18.745 3.327 2.209 8.026 7.938 4.368 13.462
    5/8 (0.6250) 15.875 15.654 30.175 28.244 8.229 24.434 24.409 3.708 2.438 9.627 9.525 5.588 16.637
    3/4 (0.7500) 19.050 18.811 36.525 34.417 10.058 30.124 30.099 4.318 2.667 12.827 12.7 5.588 19.812
    7/8 (0.8750) 22.225 21.963 42.875 40.741 11.887 35.839 35.814 4.191 2.997 14.427 14.288 6.299 22.987
    1 (1.0000) 25.400 25.110 49.225 46.761 13.716 41.529 41.503 4.597 3.302 16.027 15.875 7.543 26.162
    1 1/8 (1.1250) 28.575 28.158 55.575 52.806 15.519 47.218 47.193 4.978 3.556 19.228 19.05 8.255 30.149
    1 1/4 (1.2500) 31.750 31.333 61.925 58.826 17.348 52.908 52.882 5.384 3.810 22.479 22.225 9.093 33.324
    1 3/8 (1.3750) 34.925 34.462 68.275 64.846 19.177 58.572 58.547 5.791 4.114 22.479 22.225 10.210 36.499
    1 1/2 (1.5000) 38.100 37.637 74.625 70.891 21.005 64.262 64.236 6.172 4.394 25.908 25.4 11.049 39.674

    ASME B18.3 Flat Head Socket Screws Length Tolerances(mm)

    Nominal Length Nominal Size, Tolerances on Lengths
    0 Through
    3/8, Incl.    		 7/16 Through
    3/4, Incl.    		 7/8 Through
    1 1/2, Incl.
    Up to 25.4, incl. -0.762 -0.762 -1.270
    Over 25.4 to 63.5, incl. -1.016 -1.524 -2.540
    Over 63.5 to 152.4, incl. -1.524 -2.032 -3.556
    Over 152.4 -3.048 -3.048 -5.080

    ASME B18.3 Flat Head Socket Screws Dimension (Inch)

    Nominal Size Body Diameter, D Head Diameter, A Reference Head Height, H Protrusion Gage Diameter, G Protrusion, P Nominal Hexagon Socket Size, J Minimum Key Engagement, T Maximum Fillet Transition Diameter, F
    Max. Min. Max. Min. Max. Min. Max. Min. Min. Max.
    0 (0.0600) 0.060 0.056 0.138 0.117 0.044 0.078 0.077 0.044 0.026 0.0355 0.0350 0.025 0.072
    1 (0.0730) 0.073 0.069 0.168 0.143 0.054 0.101 0.100 0.048 0.028 0.0510 0.0500 0.031 0.089
    2 (0.0860) 0.086 0.082 0.197 0.168 0.064 0.124 0.123 0.051 0.031 0.0510 0.0500 0.038 0.106
    3 (0.0990) 0.099 0.094 0.226 0.193 0.073 0.148 0.147 0.054 0.033 0.064 0.063 0.044 0.119
    4 (0.1120) 0.112 0.107 0.255 0.218 0.083 0.172 0.171 0.057 0.036 0.064 0.063 0.055 0.136
    5 (0.1250) 0.125 0.120 0.281 0.240 0.090 0.196 0.195 0.059 0.037 0.079 0.078 0.061 0.153
    6 (0.1380) 0.138 0.132 0.307 0.263 0.097 0.220 0.219 0.060 0.037 0.079 0.078 0.066 0.168
    8 (0.1640) 0.164 0.158 0.359 0.311 0.112 0.267 0.266 0.063 0.039 0.095 0.094 0.076 0.194
    10 (0.1900) 0.190 0.184 0.411 0.359 0.127 0.313 0.312 0.066 0.041 0.127 0.125 0.087 0.220
    12 (0.2158) 0.215 0.210 0.450 0.410 0.135 0.360 0.359 0.069 0.042 0.127 0.125 0.094 0.246
    1/4 (0.2500) 0.250 0.243 0.531 0.480 0.161 0.424 0.423 0.072 0.043 0.159 0.156 0.111 0.280
    5/16 (0.3125) 0.312 0.305 0.656 0.600 0.198 0.539 0.538 0.078 0.047 0.190 0.188 0.135 0.343
    3/8 (0.3750) 0.375 0.367 0.781 0.720 0.234 0.653 0.652 0.088 0.050 0.222 0.219 0.159 0.405
    7/16 (0.4375) 0.437 0.429 0.844 0.781 0.234 0.690 0.689 0.104 0.063 0.253 0.250 0.159 0.468
    1/2 (0.5000) 0.500 0.491 0.938 0.872 0.251 0.739 0.738 0.131 0.087 0.316 0.313 0.172 0.530
    5/8 (0.6250) 0.625 0.616 1.188 1.112 0.324 0.962 0.961 0.146 0.096 0.379 0.375 0.220 0.655
    3/4 (0.7500) 0.750 0.740 1.438 1.355 0.396 1.186 1.185 0.170 0.105 0.505 0.500 0.220 0.780
    7/8 (0.8750) 0.875 0.864 1.688 1.604 0.468 1.411 1.410 0.165 0.118 0.568 0.563 0.248 0.905
    1 (1.0000) 1.000 0.988 1.938 1.841 0.540 1.635 1.634 0.181 0.130 0.631 0.625 0.297 1.030
    1 1/8 (1.1250) 1.125 1.108 2.188 2.079 0.611 1.859 1.858 0.196 0.140 0.757 0.750 0.325 1.187
    1 1/4 (1.2500) 1.250 1.233 2.438 2.316 0.683 2.083 2.082 0.212 0.150 0.885 0.875 0.358 1.312
    1 3/8 (1.3750) 1.375 1.356 2.688 2.553 0.755 2.306 2.305 0.228 0.162 0.885 0.875 0.402 1.437
    1 1/2 (1.5000) 1.500 1.481 2.938 2.791 0.827 2.530 2.529 0.243 0.173 1.020 1.000 0.435 1.562

    ASME B18.3 Flat Head Socket Screws Length Tolerances(Inch)

    Nominal Length Nominal Size, Tolerances on Lengths
    0 Through
    3/8, Incl.    		 7/16 Through
    3/4, Incl.    		 7/8 Through
    1 1/2, Incl.
    Up to 1.00, incl. -0.03 -0.03 -0.05
    Over 1.00 to 2.50, incl. -0.04 -0.06 -0.10
    Over 2.5 to 6.00, incl. -0.06 -0.08 -0.14
    Over 6.00 -0.12 -0.12 -0.20
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