ASME B18.6.3 Type 1A Cross Recessed 100 Deg Flat Countersunk Head Machine Screws

ASME B18.6.3 Type 1A Cross Recessed 100 Deg Flat Countersunk Head Machine Screws

Dimensions of ASME B18.6.3 Type 1A Cross Recessed 100 Deg Flat Countersunk Head Machine Screws

Nominal Size or Baic Screw Diameter Head Diameter, A Head Height, H, Ref. Recess Diameter, M, Ref. Recess Depth, T, Ref. Recess Width, N, Ref. Driver Size Recess Penetration Gaging Depth Protrusion Above Gaging Diameter, F Gaging Diameter, G
Max Min Max Min Max Min
0 0.112 0.095 0.026 0.054 0.028 0.018 0 0.029 0.013 0.020 0.012 0.074
1 0.137 0.118 0.031 0.062 0.036 0.018 0 0.037 0.021 0.021 0.013 0.098
2 0.162 0.142 0.037 0.088 0.048 0.028 1 0.046 0.030 0.022 0.014 0.121
3 0.187 0.165 0.043 0.096 0.055 0.029 1 0.053 0.037 0.024 0.015 0.144
4 0.212 0.188 0.049 0.110 0.070 0.029 1 0.068 0.052 0.025 0.016 0.167
6 0.262 0.235 0.060 0.148 0.077 0.041 2 0.071 0.053 0.028 0.017 0.214
8 0.312 0.282 0.072 0.162 0.092 0.041 2 0.086 0.068 0.031 0.019 0.261
10 0.362 0.329 0.083 0.178 0.107 0.041 2 0.101 0.083 0.034 0.021 0.307
1/4 0.477 0.437 0.110 0.240 0.126 0.056 3 0.114 0.096 0.040 0.025 0.415
5/16 0.597 0.550 0.138 0.310 0.163 0.085 4 0.145 0.127 0.047 0.030 0.526
3/8 0.717 0.662 0.165 0.336 0.187 0.085 4 0.170 0.152 0.053 0.034 0.638

Note :

  • Where specifying nominal size in decimals, zeros preceding the decimals and in the fourth decimal place shall be omitted.
  • Tabulated values determined from formula for maximum H in Appendix A.
  • 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.