ASME B18.6.3 Combination Slotted Type 3 Square Recessed Truss Head Machine Screws

ASME B18.6.3 Combination Slotted - Type 3 Square Recessed Truss Head Machine Screws

Dimensions of ASME B18.6.3 Combination Slotted Type 3 Square Recessed Truss Head Machine Screws

Nominal Size or Basic Screw Diameter Head Diameter, A Head Height, H Slot Width, J Slot Depth, D Recess Across Flats, M Recess Depth, T Recess Size Recess Penetration Gaging Depth, P
Max Min Max Min Max Min Max Min Max Min
2 0.194 0.180 0.053 0.044 0.031 0.023 0.031 0.020 0.050 0.057 00 0.033 0.028
3 0.226 0.211 0.061 0.051 0.035 0.027 0.036 0.023 0.070 0.066 0 0.038 0.028
4 0.257 0.241 0.069 0.059 0.039 0.031 0.040 0.027 0.070 0.066 0 0.038 0.028
5 0.289 0.272 0.078 0.066 0.043 0.035 0.045 0.030 0.091 0.096 1S 0.055 0.040
6 0.321 0.303 0.086 0.074 0.048 0.039 0.050 0.033 0.091 0.096 1S 0.055 0.040
8 0.384 0.364 0.102 0.088 0.054 0.045 0.058 0.040 0.112 0.115 2S 0.063 0.048
10 0.448 0.425 0.128 0.113 0.060 0.050 0.068 0.048 0.112 0.115 2R 0.075 0.060
12 0.511 0.487 0.134 0.118 0.067 0.056 0.077 0.055 0.133 0.143 3S 0.080 0.065
1/4 0.573 0.546 0.150 0.133 0.075 0.064 0.087 0.063 0.133 0.143 3S 0.080 0.065
5/16 0.698 0.666 0.183 0.162 0.084 0.072 0.106 0.076 0.191 0.194 4R 0.100 0.085
3/8 0.823 0.787 0.215 0.191 0.094 0.081 0.124 0.090 0.191 0.194 4R 0.100 0.085

Note :

  • Where specifying nominal size in decimals, zeros preceding the decimals and in the fourth decimal place shall be omitted.
  • Due to the underfill of material caused by the combination recess, the minimum slot depths are approximately 10% lower than slotted truss heads.
  • "R" in the recess size tabulation means regular depth recess
  • Square recesses incorporate a slight taper on the sides od the recess. This taper can result in loss of penetration gaging depth on finished fasteners due to the build up of plating in recesses. The recess penetrations dimensions specified here are for finished (plated) product. Manufactures should be advised that they should not use all this tolerance in the heading process, or an out of tolerance condition could exist after plating.