ASME B18.6.3 Square and Hex Machine Screw Nuts

ASME B18.6.3 Square and Hex Machine Screw Nuts

Dimensions of ASME B18.6.3 Square and Hex Machine Screw Nuts

Nominal Size or Basic Screw Diameter Width Across Flats, F Width Across Corners Thickness, H
Square, G Hex, G1
Basic Max Min Max Min Max Min Max Min
0 5/32 0.156 0.150 0.221 0.206 0.180 0.171 0.050 0.043
1 5/32 0.156 0.150 0.221 0.206 0.180 0.171 0.050 0.043
2 3/16 0.188 0.180 0.265 0.247 0.217 0.205 0.066 0.057
3 3/16 0.188 0.180 0.265 0.247 0.217 0.205 0.066 0.057
4 1/4 0.250 0.241 0.354 0.331 0.289 0.275 0.098 0.087
5 5/16 0.312 0.302 0.442 0.415 0.361 0.344 0.114 0.102
6 5/16 0.312 0.302 0.442 0.415 0.361 0.344 0.114 0.102
8 11/32 0.344 0.332 0.486 0.456 0.397 0.378 0.130 0.117
10 3/8 0.375 0.362 0.530 0.497 0.433 0.413 0.130 0.117
12 7/16 0.438 0.423 0.619 0.581 0.505 0.482 0.161 0.148
1/4 7/16 0.438 0.423 0.619 0.581 0.505 0.482 0.193 0.178
5/16 9/16 0.562 0.545 0.795 0.748 0.650 0.621 0.225 0.208
3/8 5/8 0.625 0.607 0.884 0.833 0.722 0.692 0.257 0.239

Notes :

  • Square macine screw nuts shall have tops and bottoms flat, and un-chamfered. The flat surfaces shall be perpendicular to the axis of the threaded hole pitch cylinder within a tolerance of 4 deg.
  • Hexagon machine screw nuts shall have top and bottom surfaces flat, with chamfered corners. the flat surfaces diameter shall ne equal to the maximum width acroos flats, with a tolerance of minus 15%. The bearing surface shall be perpendicular to the axis of the threaded hole pitch cylinder within a tolerance of 4 deg.
  • Bottoms of hexagon machine screw nuts may be supplied with flat, but un-chamfered surfaces at the options of the manufacturers.
  • Where specifying nominal size in decimals, zeros preceding the decimal and in the fourth decimal place shall be omitted.