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  6. ASME B18.3 Hexagon And Spline Socket Set Screws

ASME B18.3 Hexagon And Spline Socket Set Screws

ASME B18.3 Hexagon And Spline Socket Set Screws Standard covers complete general and dimensional data for hexagon and spline socket set screws recognized as an American National Standard. Also included are appendices that provide specifications for hexagon socket gages and gaging, tables showing applicability of keys and bits to these screws, drill and counterbore sizes for socket head cap screws, and formulas used for dimensional data. However, where questions arise concerning acceptance of product, the dimensions in the tables shall govern over recalculation by formula. Recess dimensions for Type VI recesses are given in Mandatory Appendix III.

ASME B18.3 Hexagon And Spline Socket Set Screws

Nominal Size Width Across Flats,F Width Across Corners,G Head Height, H Neck Relief Diameter, K Neck Relief Fillet Rad.,S Neck Relief Width, U Head Rad.,,W
Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Min.
ASME B18.6.2 - #10 0.19 0.188 0.18 0.265 0.247 0.148 0.134 0.145 0.14 0.027 0.083 0.48
ASME B18.6.2 - 1⁄4 0.25 0.25 0.241 0.354 0.331 0.196 0.178 0.185 0.17 0.032 0.1 0.62
ASME B18.6.2 - 5⁄16 0.3125 0.312 0.302 0.442 0.415 0.245 0.224 0.24 0.225 0.036 0.111 0.78
ASME B18.6.2 - 3⁄8 0.375 0.375 0.362 0.53 0.497 0.293 0.27 0.294 0.279 0.041 0.125 0.94
ASME B18.6.2 - 7⁄16 0.4375 0.438 0.423 0.619 0.581 0.341 0.315 0.345 0.33 0.046 0.143 1.09
ASME B18.6.2 - 1⁄2 0.5 0.5 0.484 0.707 0.665 0.389 0.361 0.4 0.385 0.05 0.154 1.25
ASME B18.6.2 - 9⁄16 0.5625 0.562 0.545 0.795 0.748 0.437 0.407 0.454 0.439 0.054 0.167 1.41
ASME B18.6.2 - 5⁄8 0.625 0.625 0.606 0.884 0.833 0.485 0.452 0.507 0.492 0.059 0.182 1.56
ASME B18.6.2 - 3⁄4 0.75 0.75 0.729 1.06 1.001 0.582 0.544 0.62 0.605 0.065 0.2 1.88
ASME B18.6.2 - 7⁄8 0.875 0.875 0.852 1.237 1.17 0.678 0.635 0.731 0.716 0.072 0.222 2.19
ASME B18.6.2 - 1 1 1 0.974 1.414 1.337 0.774 0.726 0.838 0.823 0.081 0.25 2.5
ASME B18.6.2 - 1 1⁄8 1.125 1.125 1.096 1.591 1.505 0.87 0.817 0.939 0.914 0.092 0.283 2.81
ASME B18.6.2 - 1 1⁄4 1.25 1.25 1.219 1.768 1.674 0.966 0.908 1.064 1.039 0.092 0.283 3.12
ASME B18.6.2 - 1 3⁄8 1.375 1.375 1.342 1.945 1.843 1.063 1 1.159 1.134 0.109 0.333 3.44
ASME B18.6.2 - 1 1⁄2 1.5 1.5 1.464 2.121 2.01 1.159 1.091 1.284 1.259 0.109 0.333 3.75
  • Designation: Square head set screws are designated by the following data in the sequence shown: Nominal size (number, fraction or decimal equivalent); threads per inch; screw length (fraction or decimal equivalent); product name; point style; material; and protective finish, if required. Examples: 1 ⁄ 4 - 20 × 3 ⁄ 4 Square Head Set Screw, Flat Point, Steel, Cadmium Plated. .500 − 13 × 1.25 Square Head Set Screw, Cone Point, Corrosion Resistant Steel.
  • Cone Point Angle, Y: For the following nominal lengths, or longer, shown according to nominal size, the cone point angle is 90° ± 2°: For size No. 10, 1 ⁄ 4; 1 ⁄ 4, 5 ⁄ 16; 5 ⁄ 16, 3 ⁄ 8; 3 ⁄ 8, 7 ⁄ 16; 7 ⁄ 16, 1 ⁄ 2; 1 ⁄ 2, 9 ⁄ 16; 9 ⁄ 16, 5 ⁄ 8; 5 ⁄ 8, 3 ⁄ 4; 3 ⁄ 4, 7 ⁄ 8; 7 ⁄ 8, 1; 1, 11 ⁄ 8; 11 ⁄ 8, 11 ⁄ 4; 11 ⁄ 4, 11 ⁄ 2; 13 ⁄ 8, 15 ⁄ 8; and for 11 ⁄ 2, 13 ⁄ 4. For shorter screws the cone point angle is 118° ± 2°.
  • Point Types: Unless otherwise specified, square head set screws are supplied with cup points. Cup points as furnished by some manufacturers may be externally or internally knurled. Where so specified by the purchaser, screws have cone, dog, half-dog, flat or oval points as given on the following page.
  • Point Angle, X: The point angle is 45°, + 5°, − 0° for screws of the nominal lengths, or longer, given just above for cone point angle, and 30° min. for shorter lengths.
Nominal Size Socket Size Cup and Flat Point Diameters Half Dog Point Oval Point Radius Min. Key Engagement Depth Lgth. Limit for Angle
Hex Spl. Dia. Lgth.
Nom Nom. Max Min. Max Max Basic Hex. Spl.
J M C P Q R T Ha TSa Yb
ASME B18.3 - #0 0.06 0.028 0.033 0.033 0.027 0.04 0.017 0.045 0.05 0.026 0.09
ASME B18.3 - #1 0.073 0.035 0.033 0.04 0.033 0.049 0.021 0.055 0.06 0.035 0.09
ASME B18.3 - #2 0.086 0.035 0.048 0.047 0.039 0.057 0.024 0.064 0.06 0.04 0.13
ASME B18.3 - 3 0.099 0.05 0.048 0.054 0.045 0.066 0.027 0.074 0.07 0.04 0.13
ASME B18.3 - #4 0.112 0.05 0.06 0.061 0.051 0.075 0.03 0.084 0.07 0.045 0.19
ASME B18.3 - #5 0.125 1⁄16 0.072 0.067 0.057 0.083 0.033 0.094 0.08 0.055 0.19
ASME B18.3 - #6 0.138 1⁄16 0.072 0.074 0.064 0.092 0.038 0.104 0.08 0.055 0.19
ASME B18.3 - #8 0.164 5⁄64 0.096 0.087 0.076 0.109 0.043 0.123 0.09 0.08 0.25
ASME B18.3 - #10 0.19 3⁄32 0.111 0.102 0.088 0.127 0.049 0.142 0.1 0.08 0.25
ASME B18.3 - 1⁄4 0.25 1⁄8 0.145 0.132 0.118 0.156 0.067 0.188 0.125 0.125 0.31
ASME B18.3 - 5⁄16 0.3125 5⁄32 0.183 0.172 0.156 0.203 0.082 0.234 0.156 0.156 0.38
ASME B18.3 - 3⁄8 0.375 3⁄16 0.216 0.212 0.194 0.25 0.099 0.281 0.188 0.188 0.44
ASME B18.3 - 7⁄16 0.4375 7⁄32 0.251 0.252 0.232 0.297 0.114 0.328 0.219 0.219 0.5
ASME B18.3 - 1⁄2 0.5 1⁄4 0.291 0.291 0.27 0.344 0.13 0.375 0.25 0.25 0.57
ASME B18.3 - 5⁄8 0.625 5⁄16 0.372 0.371 0.347 0.469 0.164 0.469 0.312 0.312 0.75
ASME B18.3 - 3⁄4 0.75 3⁄8 0.454 0.45 0.425 0.562 0.196 0.562 0.375 0.375 0.88
ASME B18.3 - 7⁄8 0.875 1⁄2 0.595 0.53 0.502 0.656 0.227 0.656 0.5 0.5 1
ASME B18.3 - 1 1 9⁄16 ... 0.609 0.579 0.75 0.26 0.75 0.562 ... 1.13
ASME B18.3 - 1 1⁄8 1.125 9⁄16 ... 0.689 0.655 0.844 0.291 0.844 0.562 ... 1.25
ASME B18.3 - 1 1⁄4 1.25 5⁄8 ... 0.767 0.733 0.938 0.323 0.938 0.625 ... 1.5
ASME B18.3 - 1 3⁄8 1.375 5⁄8 ... 0.848 0.808 1.031 0.354 1.031 0.625 ... 1.63
ASME B18.3 - 1 1⁄2 1.5 3⁄4 ... 0.926 0.886 1.125 0.385 1.125 0.75 ... 1.75
ASME B18.3 - 1 3⁄4 1.75 1 ... 1.086 1.039 1.312 0.448 1.321 1 ... 2
ASME B18.3 - 2 2 1 ... 1.244 1.193 1.5 0.51 1.5 1 ... 2.25
  • a Reference should be made to the Standard for shortest optimum nominal lengths to which the minimum key engagement depths TH and TS apply.
  • b Cone point angle Y is 90 degrees plus or minus 2 degrees for these nominal lengths or longer and 118 degrees plus or minus 2 degrees for shorter nominal lengths.
  • All dimensions are in inches. The thread conforms to the Unified Standard, Class 3A, UNC and UNF series. The socket depth T is included in the Standard and some are shown here. The nominal length L of all socket type set screws is the total or overall length. For nominal screw lengths of 1 ⁄ 16 through 3 ⁄ 16 inch (0 through 3 sizes incl.) the standard length increment is 0.06 inch; for lengths 1 ⁄ 8 through 1 inch the increment is 1 ⁄ 8 inch; for lengths 1 through 2 inches the increment is 1 ⁄ 4 inch; for lengths 2 through 6 inches the increment is 1 ⁄ 2 inch; for lengths 6 inches and longer the increment is 1 inch. Socket dimensions
  • inch. Socket dimensions are given in Table 11. Length Tolerance: The allowable tolerance on length L for all set screws of the socket type is ± 0.01 inch for set screws up to 5 ⁄ 8 inch long; ± 0.02 inch for screws over 5 ⁄ 8 to 2 inches long; ± 0.03 inch for screws over 2 to 6 inches long and ± 0.06 inch for screws over 6 inches long. Socket dimensions
  • For manufacturing details, including materials, not shown, see American National Standard ASME B18.3-1998.

ASME Material Specifications

ASTM A193/A193M Bolting, Stud Bolts, Screws
ASTM A320/A320M Bolting, Stud Bolts, Screws
ASTM A354 Bolts
ASTM A449 Hex Cap Screws, Bolts, Studs
ASTM A453/A453M Bolting, Stud Bolts, Screws, Nuts
ASTM A574/A574M Standard Specification for Alloy Steel Socket Head Cap Screws
ASTM A1014/A1014M UNS N07718 Bolting, Stud Bolts, Screws, Nuts
ASTM A1082/A1082M Bolting, Stud Bolts, Screws, Nuts
ASTM F1554 Anchor Bolts, Anchor Rods
ASTM F2882 Stud Bolts, Screws, Threaded Rod
ASTM F3042 Socket Set, Square Head Slotted Headless Screw
ASTM F3125/F3125M Heavy Hex Bolts, Screws, Studs
ASTM F468/F468M Bolting, Stud Bolts, Screws
ASTM F593 Bolting, Stud Bolts, Screws
ASTM F738/F738M Stud Bolts, Screws
ASTM F835/F835M Standard Specification for Alloy Steel Socket Button and Flat Countersunk Head Cap Screws
ASTM F837/F837M Standard Specification for Stainless Steel Socket Head Cap Screws
ASTM F880/F880M Standard Specification for Stainless Steel Socket Set Screws
ASTM F901 Aluminium Transmission Tower Bolts
ASTM F912/912M Standard Specification for Alloy Steel Socket Set Screws