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    2. ASME B18.3 Hexagon Socket Head Shoulder Screws

    ASME B18.3 Hexagon Socket Head Shoulder Screws

    Precision-ground shoulder bolts acting as axles, pivots, and guide pins in high-tolerance dies, molds, and mechanical linkages.

    ASME B18.3 Hexagon Socket Head Shoulder Screws, often called stripper bolts or guide pins, are unique fasteners featuring a threaded end, a hex socket head, and a precision-ground unthreaded "shoulder" of a specific diameter. This shoulder acts as a bearing surface, axle, or pivot point, allowing rotating or sliding components to move smoothly with minimal friction while maintaining precise alignment. They are indispensable in the tool and die industry, where they guide punch and die sets, and in mechanical linkages where they serve as low-friction pivots. The shoulder diameter is held to extremely tight tolerances, and the surface finish is often polished to reduce wear. The ASME B18.3 standard ensures that the relationship between the thread size, shoulder diameter, and head dimensions is consistent, allowing engineers to design reliable moving assemblies with confidence.

    ASME B18.3 Hexagon Socket Head Shoulder Screws

    ASME B18.3 Hexagon Socket Head Shoulder Screws Dimensions (mm)

    Nominal Size (Basic Shoulder Diameter) Shoulder Diameter, D Head Diameter, A Head Height, H Chamfer or Radius, C Nominal Hexagon Socket Size, J Key Engagement, T Fillet Transition Diameter, M Head Fillet Radius, R Shoulder Neck Diameter, K Shoulder Neck Width, F Nominal Thread Diameter, D1 Threads, in. Thread Neck Diameter, G Thread Neck Width, I Thread Neck Fillet, N Basic Thread Length, E Chamfer or Radius, P
    Max. Min. Max. Min. Max. Min. Max. Basic Decimal Min. Max. Min. Min. Max. Max. Min. Max. Max. Min. Max.
    1/8 0.1250 3.124 3.073 6.350 5.969 3.175 2.921 0.203 5/64 1.981 1.702 3.505 0.152 2.743 1.016 4 (0.1120) 40 1.930 1.753 1.981 0.406 0.254 3.988 0.203
    5/32 0.1560 3.912 3.861 7.137 6.756 3.175 2.921 0.203 3/32 2.388 1.702 4.369 0.178 3.556 1.016 6 (0.1380) 32 2.540 2.362 1.600 0.457 0.305 4.750 0.203
    3/16 0.1875 4.699 4.648 7.925 7.518 3.962 3.708 0.305 3/32 2.388 2.007 5.258 0.203 3.912 1.016 8 (0.1640) 32 3.048 2.845 1.753 0.457 0.305 4.801 0.203
    1/4 0.2500 6.299 6.248 9.525 9.068 4.775 4.496 0.508 1/8 3.175 2.388 7.010 0.229 5.766 2.362 10 (0.1900) 24 3.607 3.378 2.108 0.584 0.432 9.525 0.254
    5/16 0.3125 7.887 7.836 11.125 10.643 5.563 5.309 0.660 5/32 3.962 2.972 8.763 0.305 7.341 2.362 1/4 (0.2500) 20 4.902 4.623 2.540 0.711 0.559 11.125 0.254
    3/8 0.3750 9.474 9.423 14.275 13.792 6.350 6.096 0.787 3/16 4.775 3.581 10.490 0.381 8.941 2.362 5/16 (0.3125) 18 6.325 6.020 2.819 0.787 0.635 12.700 0.254
    1/2 0.5000 12.649 12.598 19.050 18.517 7.925 7.671 1.016 1/4 6.350 4.775 13.970 0.508 12.116 2.362 3/8 (0.3750) 16 7.722 7.391 3.175 0.889 0.737 15.875 0.254
    5/8 0.6250 15.824 15.773 22.225 21.666 9.525 9.271 1.270 5/16 7.925 5.944 17.450 0.610 15.291 2.362 1/2 (0.5000) 13 10.516 10.084 3.912 1.067 0.914 19.050 0.381
    3/4 0.7500 19.000 18.948 25.400 24.816 12.700 12.446 1.753 3/8 9.525 7.137 20.980 0.762 18.466 2.362 5/8 (0.6250) 11 13.233 12.751 4.623 1.295 1.143 22.225 0.381
    1 1.0000 25.349 25.298 33.325 32.690 15.875 15.494 2.108 1/2 12.700 9.525 27.889 1.016 24.816 3.175 3/4 (0.7500) 10 16.205 15.646 5.080 1.397 1.245 25.400 0.508
    1 1/4 1.2500 31.700 31.648 44.450 43.764 19.050 18.669 2.591 5/8 15.875 11.913 34.747 1.270 31.166 3.175 7/8 (0.8750) 9 19.050 18.440 5.639 1.575 1.422 28.575 0.508
    1 1/2 1.5000 38.049 37.998 53.975 53.213 25.400 24.892 3.505 7/8 22.225 16.662 41.605 1.524 37.541 3.175 1 1/8 (1.1250) 7 24.486 23.724 7.264 1.829 1.676 38.100 0.508
    1 3/4 1.7500 44.399 44.348 60.325 59.563 28.575 28.067 3.988 1 25.400 19.050 48.463 1.778 43.891 3.175 1 1/4 (1.2500) 7 27.661 26.899 7.264 1.829 1.676 44.450 0.508
    2 2.0000 50.749 50.698 69.850 69.088 31.750 31.242 4.470 1 1/4 31.750 23.800 55.321 2.032 50.241 3.175 1 1/2 (1.5000) 6 33.198 32.436 8.458 2.591 2.438 50.800 0.508

    ASME B18.3 Hexagon Socket Head Shoulder 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.    		 Over 1 1/2
    Up to 25.4, incl. -0.762 -0.762 -1.270 ...
    Over 25.4 to 63.5, incl. -1.016 -1.524 -2.540 -4.572
    Over 63.5 to 152.4, incl. -1.524 -2.032 -3.556 -5.080
    Over 152.4 -3.048 -3.048 -5.080 -6.096

    Frequently Asked Questions

    What does ASME B18.3 hexagon socket head shoulder screws cover?
    ASME B18.3 is the inch dimensional standard for hexagon socket head shoulder screws. It defines head dimensions, body diameter, thread length, total length, drive recess, and tolerances so any compliant hexagon socket head shoulder screws interchanges with standard nuts, washers and wrenches across manufacturers.
    What size range is available for hexagon socket head shoulder screws under ASME B18.3?
    hexagon socket head shoulder screws under ASME B18.3 covers 1/4 in to 2 in shoulder diameter for pivot, slide and guide applications. TorqBolt manufactures the full range in ASTM A193 Grades B7, B7M, B8, B8M and the full ASTM A320 cryogenic counterpart on customer specification.
    What is the metric/inch counterpart of ASME B18.3 hexagon socket head shoulder screws?
    The companion specification for hexagon socket head shoulder screws is ASME B18.3.7M metric shoulder screws. Both standards share equivalent functional dimensions but use the corresponding measurement system (inch vs metric ISO M-series).
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