• Top of Head. Top of head shall be full form and chamfered with the diameter of chamfer circle being equal to the maximum width across flats, within a tolerance of minus 15%.
  • Wrenching Height, J. Wrenching height is a distance measured from the bearing surface up the side of the head at the corners. The width across corners shall be within the specified limits for minimum wrenching height.
  • Bearing Surface. Bearing surface shall be flat and washer faced. Diameter of washer face shall be equal to the maximum width across flats within a tolerance of minus 10 percent.
    Thickness of the washer face shall be not less than 0.015 in. nor greater than 0.025 in. for screw sizes 3/4 in. and smaller, and not less than 0.015 in. nor greater than 0.035 in. for sizes larger than 3/4 in. Measurement of washer face diameter shall be taken at a height of 0.004 in. above the bearing surface.
Unit of Measure

Manufacturer

Manufacturer

N/A Industrial Fasteners Institute

Specifications

Product

N/A Square and Hex Bolts and Screws

Unit of Measure

N/A English

Nominal Size or Basic Product Diameter

N/A 2-3/4 in

Nominal Size or Basic Product Diameter (Decimal)

N/A 2.7500 in

Max. Body Diameter (E)

N/A 2.7500 in

Min. Body Diameter (E)

N/A 2.711 in

Basic Width Across Flats (F)

N/A 4-1/4 in

Max. Width Across Flats (F)

N/A 4.250 in

Min. Width Across Flats (F)

N/A 4.112 in

Max. Width Across Corners (G)

N/A 4.907 in

Min. Width Across Corners (G)

N/A 4.688 in

Basic Head Height (H)

N/A 1-11/16 in

Max. Head Height (H)

N/A 1.744 in

Min. Head Height (H)

N/A 1.632 in

Min. Wrenching Height (J)

N/A 1.151 in

Max. Transition Thread Length (Y)

N/A 1.250 in

Max. Circular Runout of Bearing Surface FIM

N/A 0.074 in

Codes and Standards

Codes and Standards

N/A ASME B18.2.1 1996

Thread Length for Screw Lengths

Nom. LT for Screw Length (Over 6 in.)

N/A 6.000 in
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