ASME B18.6.3 Type 2 Cross Recessed Undercut Flat Countersunk Head Machine Screws

ASME B18.6.3 Type 2 Cross Recessed Undercut Flat Countersunk Head Machine Screws

Dimensions of ASME B18.6.3 Type 2 Cross Recessed Undercut Flat Countersunk Head Machine Screws

Nominal Size or Basic Screw Diameter Length, L Head Diameter, A Head Height, H Recess Diameter, M Recess Depth, T Recess Width, N Driver Size Recess Penetration Gaging Depth Protrusion Above Gaging Diameter, F Gaging Diameter, G
Max Min Max Min Max Min Max Min
0 1/8 0.112 0.096 0.025 0.018 0.067 0.029 0.020 Note 5 Note 5 Note 5 Note 5 Note 5
1 1/8 0.137 0.120 0.031 0.023 0.082 0.039 0.022 Note 5 Note 5 Note 5 Note 5 Note 5
2 1/8 0.162 0.144 0.036 0.028 0.100 0.050 0.025 0.030 0.020 0.029 0.017 0.124
3 1/8 0.187 0.167 0.042 0.033 0.111 0.058 0.026 0.038 0.027 0.031 0.018 0.148
4 3/16 0.212 0.191 0.047 0.038 0.129 0.070 0.029 0.050 0.038 0.032 0.019 0.172
5 3/16 0.237 0.215 0.053 0.043 0.147 0.080 0.032 0.062 0.050 0.034 0.020 0.196
6 3/16 0.262 0.238 0.059 0.048 0.161 0.088 0.034 0.071 0.059 0.036 0.021 0.220
8 1/4 0.312 0.285 0.070 0.058 0.197 0.112 0.039 0.095 0.082 0.039 0.023 0.267
10 5/16 0.362 0.333 0.081 0.068 0.236 0.132 0.045 0.121 0.107 0.042 0.025 0.313
12 3/8 0.412 0.380 0.092 0.078 0.260 0.148 0.048 0.137 0.122 0.045 0.027 0.362
1/4 7/16 0.477 0.442 0.107 0.092 0.304 0.169 0.054 0.167 0.150 0.050 0.029 0.424
5/16 1/2 0.597 0.556 0.134 0.116 0.381 0.218 0.066 0.218 0.198 0.057 0.034 0.539
3/8 9/16 0.717 0.670 0.161 0.140 0.453 0.266 0.077 0.266 0.244 0.065 0.039 0.653
7/16 5/8 0.760 0.715 0.156 0.133 0.498 0.295 0.083 0.296 0.273 0.073 0.044 0.690
1/2 3/4 0.815 0.765 0.156 0.130 0.548 0.328 0.090 0.329 0.305 0.081 0.049 0.739

Note :

  • Where specifying nominal size in decimals, zeros preceding the decimals and in the fourth decimal place shall be omitted.
  • Screws of these length and shorter shall have undercut heads. Screws of longer lengths shall have head heights.
  • Point same on all drivers.
  • No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protusion values must be recalculated using the formulas.
  • No practical to gage.