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Reprinted from ASME B18.3-2003, by permission of The American Society of Mechanical Engineers. All rights reserved.
SOCKET CAP, SHOULDER, AND SET SCREWS, ASME B18.3-2003
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| Nominal Size or Basic Screw Diameter [Note (5)] |
J | M | T | C | R | Y | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Nominal Hexagon Socket Size [Note (8)] |
Nominal
Number of Splines and Spline Socket Size [Note (9)] |
Min. Key Engagement to Develop Functional Capability of Key [Note (10)] |
Cup and Flat Point Diameters [Note (5)] |
Basic Oval Point Radius [Note (6)] |
Cone Point Angle 90 deg + 2 deg for These Nominal Lengths or Longer: 118 + 2 deg for Shorter Nominal Lengths [Note (5)] |
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| Hex Socket, TH |
Spline Socket, TS |
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| Max. | Min. | ||||||||||
0 |
0.0600 0.0730 0.0860 0.0990 |
... ... ... ... |
0.028 0.035 0.035 0.050 |
4 4 4 and 6 4 and 6 |
.033 0.033 0.048 0.048 |
0.050 0.060 0.060 0.070 |
0.026 0.035 0.040 0.040 |
0.033 0.040 0.047 0.054 |
0.027 0.033 0.039 0.045 |
0.045 0.055 0.064 0.074 |
0.09 0.09 0.13 0.13 |
| 4 5 5 6 |
0.1120 0.1250 0.1250 0.1380 |
... 1/16 1/16 1/16 |
0.050 0.062 0.062 0.062 |
6 4 6 6 |
0.060 0.069 0.072 0.072 |
0.070 0.080 0.080 0.080 |
0.045 0.055 0.055 0.055 |
0.061 0.067 0.067 0.074 |
0.051 0.057 0.057 0.064 |
0.084 0.094 0.094 0.104 |
0.19 0.19 0.19 0.19 |
| 6 8 10 1/4 |
0.1380 0.1640 0.1900 0.2500 |
1/16 5/64 3/32 1/8 |
0.062 0.078 0.094 0.125 |
4 6 6 6 |
0.076 0.096 0.111 0.145 |
0.080 0.090 0.100 0.125 |
0.055 0.080 0.080 0.125 |
0.074 0.087 0.102 0.132 |
0.064 0.076 0.088 0.118 |
0.104 0.123 0.142 0.188 |
0.19 0.25 0.25 0.31 |
| 5/16 3/8 7/16 1/2 |
0.3125 0.3750 0.4375 0.5000 |
5/32 3/16 7/32 1/4 |
0.156 0.188 0.219 0.250 |
6 6 6 6 |
0.183 0.216 0.251 0.291 |
0.156 0.188 0.219 0.250 |
0.156 0.188 0.219 0.250 |
0.172 0.212 0.252 0.291 |
0.156 0.194 0.232 0.270 |
0.234 0.281 0.328 0.375 |
0.38 0.44 0.50 0.57 |
| 5/8 | 0.6250 | 5/16 | 0.312 | 6 | 0.372 | 0.312 | 0.312 | 0.371 | 0.347 | 0.469 | 0.75 |
Cam-Tech Industries, Inc. only manufactures up to 5/8" diameter. |
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* Where both six and four splines are available, six splines will be supplied unless four splines are ordered. |
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TABLE 5A DIMENSIONS OF HEXAGON AND SPLINE SOCKET SET SCREWS |
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| P | Q | B | B1 | ||||||
| Half Dog Point [Notes (5), (11)] |
Shortest Optimum Nominal Length to Which TH Applies [Notes (4), (5), (10)] |
Shortest Optimum Nominal Length to Which Ts Applies [Notes (4), (5), (10)] |
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| Diameter | Length | Cup and Flat Points |
90 deg Cone and Oval Points |
Half Dog Point |
Cup and Flat Points |
90 deg Cone and Oval Points |
Half Dog Point |
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| Max. | Min. | Max. | Min. | ||||||
| 0.040 0.049 0.057 0.066 |
0.037 0.045 0.053 0.062 |
0.017 0.021 0.024 0.027 |
0.013 0.017 0.020 0.023 |
0.13 0.13 0.13 0.19 |
0.13 0.19 0.19 0.19 |
0.13 0.13 0.19 0.19 |
0.06 0.13 0.13 0.13 |
0.13 0.19 0.19 0.19 |
0.13 0.13 0.19 0.19 |
| 0.075 0.083 0.083 0.092 |
0.070 0.078 0.078 0.087 |
0.030 0.033 0.033 0.038 |
0.026 0.027 0.027 0.032 |
0.19 0.19 0.19 0.19 |
0.19 0.19 0.19 0.25 |
0.19 0.19 0.19 0.19 |
0.13 0.13 0.13 0.13 |
0.19 0.19 0.19 0.25 |
0.19 0.19 0.19 0.19 |
| 0.092 0.109 0.127 0.156 |
0.087 0.103 0.120 0.149 |
0.038 0.043 0.049 0.067 |
0.032 0.037 0.041 0.059 |
0.19 0.19 0.19 0.25 |
0.25 0.25 0.25 0.31 |
0.19 0.25 0.25 0.31 |
0.13 0.19 0.19 0.25 |
0.25 0.25 0.25 0.31 |
0.19 0.25 0.25 0.31 |
| 0.203 0.250 0.297 0.344 |
0.195 0.241 0.287 0.334 |
0.082 0.099 0.114 0.130 |
0.074 0.089 0.104 0.120 |
0.31 0.38 0.44 0.50 |
0.44 0.44 0.63 0.63 |
0.38 0.44 0.50 0.63 |
0.31 0.38 0.44 0.50 |
0.44 0.44 0.63 0.63 |
0.38 0.44 0.50 0.63 |
| 0.469 | 0.456 | 0.164 | 0.148 | 0.63 | 0.88 | 0.88 | 0.63 | 0.88 | 0.88 |
| Cam-Tech Industries, Inc. only manufactures up to 5/8" diameter. | |||||||||
Reprinted from ASME B18.3-2003, by permission of The American Society of Mechanical Engineers. All rights reserved.
SOCKET CAP, SHOULDER, AND SET SCREWS,
HEX AND SPLINE KEYS (INCH SERIES)
ASME B18.3-2003
Table
5A Dimensions of Hexagon and Spline Socket Set Screws (Cont'd)
GENERAL NOTE: For additional
requirements, refer to Notes (4) through (17) and section 2, General Data, of
this Standard.
NOTES:
(1) Nominal Size. Where specifying nominal size in
decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
(2) Length. The length of the screw shall be measured overall, parallel to the axis of the
screw. The basic length dimension on the product shall be the nominal length expressed as
a two-place decimal.
(3) Standard Lengths. Standard length increments for set screws shall be as tabulated
below.
| Nominal Screw Length | Standard Length Increment |
| 0.13 through 0.19 [Note (1)] | 0.03 |
| 0.13 through 0.50 | 0.06 |
| 0.50 through 1.00 | 0.13 |
| 1.00 through 2.00 | 0.25 |
| 2.00 through 6.00 | 0.50 |
| Over 6.00 | 1.00 |
NOTE:
*A nominal screw length of 0.13 through 0.19 is applicable only to nominal sizes 0 (0.060 in.) through 3 (0.099 in.), inclusive.
(4) Face. The plane of the face on the
socket end of the screw shall be approximately normal to the axis of the screw,
and shall be chamfered on screws longer than lengths listed in this Table,
columns B and B1. The chamfer angle V shall be
between 30 deg and 45 deg. The chamfer shall extend slightly below the
root diameter of the thread and the edge between flat and chamfer may be
slightly rounded. For screws equal to or shorter than the lengths listed
in thisTable, columns B and B1, or screws 0.250 in. diameter or
greater, with a national coarse thread, including lengths longer than listed in
the Table, column B and B1, chamfering shall be at the option of
the manufacturer. If chamfered, the chamfer angle V shall not
exceed 45 deg.
(5) Point Angles. Point angles specified shall apply
only to those portions of the angles that lie below the root diameter of the
thread. The angles may vary in the threaded portions due to manufacturing
processes.
W shall be 45 deg, +5 deg -0 deg, for screws of
lengths equal to or longer than the lengths list in the Table, columns B
an B1, and 30
deg
minimum for shorter screws.
(6) Oval Point Radius Tolerance. The tolerance shall be +0.015 in. for screw nominal sizes through 5 (0.125 in.) and +0.031 in. for screw nominal sizes 6 (0.138 in.) and larger.
(7) Cone Point Configuration. The apex of the cone may be flatted or rounded to the extent of 10% of the basic diameter of the screw.
(8) Hexagon Sockets. See Table 6 for hexagon socket dimensions and Mandatory Appendix I for gaging of hexagon sockets.
(9) Spline Sockets. See Table 7 for spline socket dimensions and Mandatory Appendix I for gaging of spline sockets.
(10) Socket Depths. The key engagement dimensions given in columns TH and TS of this Table shall apply only to nominal screw lengths equal to or longer than the lengths listed in the Table, columns B and B1, respectively. For hexagon socket key engagement dimensions in screws of shorter nominal lengths than those listed in column B of this Table, see Table 5B. Spline sockets in screws shorter than those listed in column B1 of this Table, shall be as deep as practicable.
(11) Half Dog Point Runout. The runout of the half dog
point shall not exceed 3% of the nominal size and shall not exceed 0.010 FIM for
nominal sizes up to and including 3/4 in. diameter and 0.020 FIM for nominal
sizes over 3/4 in. diameter.
Runout is defined as the full indicator movement (FIM)
obtained by holding on the thread major diameter near the half dog point, and
rotating the screw 360 deg and indicating on the half dog point diameter.
(12) Where both six and four splines are available, six splines will be supplied unless four splines are ordered.
(13) Tolerance on Length. Tolerance on length of set screws shall be as tabulated below.
| Nominal Screw Length | Tolerance on Length |
| Up to 0.63, incl. | ±0.01 |
| Over 0.63 to 2.00, incl. | ±0.02 |
| Over 2.00 to 6.00, incl. | ±0.03 |
| Over 6.00 | ±0.06 |
(14) Threads. Threads shall be Unified external thread: Class 3A, UNC and UNF Series.
Thread lead deviation is controlled by standard thread gages within a thread length equal to 1.5 basic thread diameters. When using set screws longer than 1.5 basic diameters in length, the pitch diameter of the set screw may need to be reduced, or the tapped hole's pitch diameter may need to be increased to avoid interference during assembly.
For all thread diameters # 5 and smaller, thread acceptability will be based on System 21, ASME B1.3M.
For all thread diameters # 6 and larger, thread acceptability will be based on System 22, ASME B1.3M when the set screw thread length has a minimum of 7 pitch lengths.
For all set screws equal or shorter than 7 pitch lengths, thread acceptability will be based on System 21, ASME 1313M. The chart below shows the lengths equal to 7 pitch lengths.
| Threads/in. | 7 Pitch Lengths | Threads/in. | 7 Pitch Lengths |
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40 |
0.175 |
12 11 10 9 8 7 6 5 4-1/2 |
0.583 0.636 0.700 0.778 0.875 1.000 1.167 1.400 1.556 |
Class 3A threads do not provide a plating allowance. When set screws must be plated, they should be manufactured with an undersized pitch diameter to accommodate the plating. When plated products are required, it is recommended that they be procured from the manufacturer (see para. 1.10, Introductory Notes).
When standard socket set screws are plated, thread interference is likely to occur during assembly.
(15) Material
(a) Steel, Alloy. Socket set screws shall be fabricated from alloy steel and shall conform in all respects to ASTM F 912.
(b) Steel, Corrosion -Resistant. Socket set screws shall be fabricated from austenitic corrosion-resistant steel and shall conform in all respects to ASTM F 880.
(16) Flat Point. The plane of the end on the flat point shall be perpendicular to the axis of the thread within 2 deg obtained by holding the screw on the major thread diameter near the flat point, and inspecting on an optical comparator or comparable inspection equipment.
(17) Dimensional Conformance. Socket set screws shall have the following designated characteristics inspected to ASME
1318.18.2M to Inspection Level C:
(a) threads
(b) minimum key engagement
(c) socket size (gaged)
(d) length
(18) Designation. To promote uniformity and understanding in communications relating to products conforming to this Standard, it is recommended that Hexagon and Spline Socket Set Screws be designated in accordance with the following data, preferably in the sequence shown: (a) product name and point style IJ designation of the standard (c) nominal size (number, fractional or decimal equivalent) (d) thread pitch (e) nominal length (fractional or decimal equivalent) (P material (g) protective finish, if required
EXAMPLES:
Hexagon Socket Set Screw, Cup Point, ASME J 1/4-20 X 1/4, Alloy Steel
Spline Socket Set Screw, Flat Point, ASME J 0.112-40 X 0.125, Alloy Steel, Zinc Plated. (For plated products,
see para. 1.7, Introductory Notes.)
Hexagon Socket Set Screw, Cup Point, ASME 11318.3, 6-32 x 0.250, Corrosion-Resistant Steel
For the recommended B18 part identifying numbering system (PIN), see ASME B18.24.1.
Reprinted from ASME B18.3-2003, by permission of The American Society of Mechanical Engineers. All rights reserved.
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