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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

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.