Socket Set Screws: Sizes - Dimensions & Specifications

Labeled Diagrams of Socket Set Screws

Socket Set Screw Dimensions (Alloy Steel)                                                                                                     ASME B18.3-2003
Nominal Size**

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 Key Engage-ment (K) Cup & Flat Point Diameter (F) Oval Point Radius (R)  Cone Point Angle* (A)
 Half Dog Point
Diameter (D)
 Length (H)
Min Max Min Basic Max  Min  Max Min
0 0.050 0.033 0.027 0.045 0.09 0.040 0.037 0.017 0.013
1 0.060 0.040 0.033 0.055 0.09 0.049 0.045 0.021 0.017
2 0.060 0.047 0.039 0.064 0.13 0.057 0.053 0.024 0.020
3 0.070 0.054 0.045 0.074 0.13 0.066 0.062 0.027 0.023
4 0.070 0.061 0.051 0.084 0.19 0.075 0.070 0.030 0.026
5 0.080 0.067 0.057 0.094 0.19 0.083 0.078 0.033 0.027
6 0.080 0.074 0.064 0.104 0.19 0.092 0.087 0.038 0.032
8 0.090 0.087 0.076 0.123 0.25 0.109 0.103 0.043 0.037
10 0.100 0.102 0.088 0.142 0.25 0.127 0.120 0.049 0.041
1/4 0.125 0.132 0.118 0.188 0.31 0.156 0.149 0.067 0.059
5/16 0.156 0.172 0.156 0.234 0.38 0.203 0.195 0.082 0.074
3/8 0.188 0.212 0.194 0.281 0.44 0.250 0.241 0.099 0.089
7/16 0.219 0.252 0.232 0.328 0.50 0.297 0.287 0.114 0.104
1/2 0.250 0.291 0.270 0.375 0.57 0.344 0.334 0.130 0.120
5/8 0.312 0.371 0.347 0.469 0.75 0.469 0.456 0.164 0.148
3/4 0.375 0.450 0.425 0.562 0.88 0.562 0.549 0.196 0.180
7/8 0.500 0.530 0.502 0.656 1.00 0.656 0.642 0.227 0.211
1 0.562 0.609 0.579 0.750 1.13 0.750 0.734 0.260 0.240

*Angle is 90-degrees (+/-2 degrees) for these lengths and over, and it is 118-degress (+/-2 degrees) for shorter lengths.

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Socket Set Screws : Nominal Screw Length

Tolerance on Length

 Nominal Screw Length
Up to 0.63" (Inclusive) Over 0.63" - 2" (Inclusive) Over 2" - 6"
+/-0.01 +/-0.02 +/-0.03
Socket Set Screws (Alloy Steel)ASME B18.3-2003
Nominal Size

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 Shortest Nominal Length to Which Column A Applies Hex Key Size (S)
  Tightening Torque (inch/lbs.)
Cup & Flat Point Cone & Oval Point Half Dog Point
0 0.13 0.13 0.13 0.028 0.86
1 0.13 0.19 0.13 0.028 0.86
2 0.13 0.19 0.19 0.035 1.8
3 0.19 0.19 0.19 0.050 5
4 0.19 0.19 0.19 0.050 5
5 0.19 0.19 0.19 1/16 9.5
6 0.19 0.25 0.19 1/16 9.5
8 0.19 0.25 0.25 5/64 19.4
10 0.19 0.25 0.25 3/32 33.5
1/4 0.25 0.31 0.31 1/8 77.9
5/16 0.31 0.44 0.38 5/32 156
3/8 0.38 0.44 0.44 3/16 273
7/16 0.44 0.63 0.50 7/32 428
1/2 0.50 0.63 0.63 1/4 615
5/8 0.63 0.88 0.88 5/16 1315
3/4 0.75 1.00 1.00 3/8 2150
7/8 0.8 1.00 1.00 1/2 5130
1 1.00 1.25 1.25 9/16 7010
Socket Set Screws Mechanical Properties                                                                                                ASME B18.3-2003
 

Cup Point

Cup Point Set Screw

Half-Dog Point

1/2 Dog Point Set Screw

Oval Point

Oval Point Set Screw

Flat Point

Flat Point Set Screw

Cone Point

Cone Point Set Screw
Description Fully threaded, headless screw with a hexagonal drive at one end and a cup-shaped indentation at the other. Fully-threaded, headless screw with a hex drive at one end and a protruding tip with a flat surface at the opposing end. Possesses an oval-shaped point on the end opposing the flush hex drive. Possesses a flat surface at the end opposing the hexagonal drive.   Has a short conical-shaped point at the opposite end from the hexagonal drive.
Applications/ Advantages
  • Most used style
  • Designed for fast, permanent and semi-permanent location of parts on shafts with a hardness differential of 10-15 Rockwell C points and where cutting in of the cup edge on the shaft is acceptable.
  •  For permanent setting - often used instead of a dowel pin.
  • The point should closely fit the diameter of the drilled hole, or alternatively, against the flat.
  • The preferred style for frequent re-set on soft or hard shafts with minimum deforming.
  • Often used for permanent setting on shafts that are spotted, splined or grooved, and for applications where the point meets the shaft on an angle.
  • Sometimes substituted for the cup point style.
  •  Designed for frequent re-setting or re-locating on hard steel shafts and where minimal damage is shafts is essential.
  • Ground flats on the shaft improves the contacts.
  • Designed for permanent setting on soft or hardened shafts.
  • Deep penetration gives this style of screw the highest torsional and axial holding power.
  • Can be used as a hangar or pivot.
  • For shafts of Rockwell hardness C15 or more, spot point half its depth.
Material Made from alloy steel with a chemical composition of: 0.28 to 0.50% Carbon, 0.040% (max) Phosphorus, and 0.045% (max) Sulfur. Also, chromium, nickel, molybdenum or vanadium should be present in a quantity sufficient to meet the strength requirements outlined below.
Heat Treatment Set screws should be heat treated via oil quenching from above the transformation temperature and then tempered at a temperature that is conducive to meeting the hardness requirements.
Hardness Rockwell C45 - 53
Torsional Strength Socket set screws of sufficient length should be tested to determine if that can withstand the application of the test torque outlined in the above table without evidence of the socket reaming or the screw bursting.
Finish Black Thermal Finish