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Square and Hex Bolts and Screws
square-and-hex-bolts-and-screws
Square Bolts
(13)- Surface Condition. Bolts need not be finished on any surface except threads.
- 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 percent.
- Head Taper. Maximum width across flats and across corners shall not be exceeded. No transverse section through the head between 25 percent and 75 percent of actual head height, as measured from the bearing surface, shall be less than the minimum width across flats and across corners.
- Bearing Surface. A die seam across the bearing surface is permissible. Bearing surface shall be perpendicular to the axis of the body within a tolerance of 3 deg for 1 in. size and smaller, and 2 deg for sizes larger than 1 in. Angularity measurement shall be taken at a location to avoid interference from a die seam. Special bearing surface finishes may be provided as agreed between purchaser and manufacturer.
- True Position of Head. The axis of the head shall be located at true position with respect to the axis of the body (determined over a distance under the head equal to one diameter) within a tolerance zone having a diameter equivalent to 6 percent of the maximum width across flats, regardless of feature size.
Hex Bolts
(23)- Surface Condition. Bolts need not be finished on any surface except threads.
- 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 percent.
- Head Taper. Maximum width across flats and across corners shall not be exceeded. No transverse section through the head between 25 percent and 75 percent of actual head height, as measured from the bearing surface, shall be less than the minimum width across flats and across corners.
- Bearing Surface. A die seam across the bearing surface is permissible. Bearing surface shall be perpendicular to the axis of the body within a tolerance of 3 deg for 1.
Heavy Hex Bolts
(15)- Surface Condition. Bolts need not be finished on any surface except threads.
- 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 percent.
- Head Taper. Maximum width across flats and across corners shall not be exceeded. No transverse section through the head between 25 percent and 75 percent of actual head height, as measured from the bearing surface, shall be less than the minimum width across flats and across corners.
- Bearing Surface. A die seam across the bearing surface is permissible. Bearing surface shall be perpendicular to the axis of the body within a tolerance of 3 deg for 1 in. size and smaller, and 2 deg for sizes larger than 1 in. Angularity measurement shall be taken at a location to avoid interference from a die seam.
- True Position of Head. The axis of the head shall be located at true position with respect to the axis of the body (determined over a distance under the head equal to one diameter) within a tolerance zone having a diameter equivalent to 6 percent of the maximum width across flats, regardless of feature size.
Hex Cap Screws
(20)- 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 percent.
- 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 specified limits for the full wrenching height.
- Bearing Surface. Bearing surface shall be flat and washer
Heavy Hex Screws
(15)- 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.
