Socket Head Cap Screw
Dimensions and Specifications




Head and Body Dimensions - Alloy and Stainless
ASME B18.3-1998 - Includes 1960 Series

Screw
Diam.
D A H C J F T G K
Body Diameter Head Diameter Head Height Top
Chamfer
or
Radius
Hex
Socket
Size
Fillet Transition
Diameter
Key
Engage-
ment
Wall
Thick-
ness
Bottom
Chamfer
or
Radius
0 .0600 .0568 .0960 .091 .060 .057 .004 .050 .074 .063 .025 .020 .007
1 .0730 .0695 .118 .112 .073 .070 .005 1/16 .087 .076 .031 .025 .007
2 .0860 .0822 .140 .134 .086 .083 .008 5/64 .102 .090 .038 .029 .007
3 .0990 .0949 .161 .154 .099 .095 .008 5/64 .115 .103 .044 .034 .007
4 .1120 .1075 .183 .176 .112 .108 .009 3/32 .130 .118 .051 .038 .008
5 .1250 .1202 .205 .198 .125 .121 .012 3/32 .145 .132 .057 .043 .008
6 .138 .1329 .226 .218 .138 .134 .013 7/64 .158 .145 .064 .047 .008
8 .1640 .1585 .270 .262 .164 .159 .014 9/64 .188 .173 .077 .056 .008
10 .1900 .1840 .312 .303 .190 .185 .018 5/32 .218 .202 .090 .065 .008
1/4 .2500 .2435 .375 .365 .250 .244 .025 3/16 .278 .262 .120 .095 .010
5/16 .3125 .3053 .469 .457 .312 .306 .033 1/4 .347 .329 .151 .119 .010
3/8 .3750 .3678 .562 .550 .375 .368 .040 4/15 .415 .398 .182 .143 .010
7/16 .4375 .4294 .656 .642 .438 .430 .047 3/8 .484 .465 .213 .166 .015
1/2 .5000 .4919 .750 .735 .500 .492 .055 3/8 .552 .532 .245 .190 .015
5/8 .6250 .6163 .938 .921 .625 .616 .070 1/2 .689 .664 .307 .238 .015
3/4 .7500 .7406 1.125 1.107 .750 .740 .085 5/8 .828 .801 .370 .285 .015
7/8 .8750 .8647 1.312 1.293 .875 .864 .100 3/4 .963 .933 .432 .333 .020
1 1.0000 .9886 1.500 1.479 1.000 .988 .114 3/4 1.100 1.069 .495 .380 .020
1-1/4 1.2500 1.2336 1.875 1.852 1.250 1.236 .144 7/8 1.370 1.334 .620 .475 .020
1-1/2 1.5000 1.4818 2.250 2.224 1.500 1.485 .176 1 1.640 1.602 .745 .570 .020



Length Specifications - Alloy and Stainless
ASME B18.3-1998 - Includes 1960 Series

Nominal
Size D
0 1 2 3 4 5 6 8 10
Basic Thread
Length LT
.500 .625 .625 .625 .750 .750 .750 .875 .875
Nominal
Length L
LG LB LG LB LG LB LG LB LG LB LG LB LG LB LG LB LG LB
1.00 .50 .44 .25 .17 .25 .16 .25 .15 .25 .12 .25 .12
1.25 .75 .69 .62 .55 .62 .54 .62 .52 .25 .12 .25 .12 .50 .34 .38 .22 .38 .17
1.50 .88 .80 .88 .79 .88 .77 .75 .62 .75 .62 .50 .34 .38 .22 .38 .17
1.75 1.12 1.04 1.12 1.02 .75 .62 .75 .62 1.00 .84 .88 .72 .88 .67
2.00 1.38 1.27 1.25 1.12 1.25 1.12 1.00 .84 .88 .72 .88 .67
2.25 1.25 1.12 1.25 1.12 1.50 1.34 1.38 1.22 1.38 1.17
2.50 1.75 1.62 1.50 1.34 1.38 1.22 1.38 1.17
2.75 2.00 1.84 1.88 1.72 1.88 1.67
3.00 1.88 1.72 1.88 1.67
3.50 2.38 2.17



Length Specifications - Alloy and Stainless
ASME B18.3-1998 - Includes 1960 Series

Nominal
Size D
1/4 5/16 3/8 7/16 1/2 5/8 3/4 7/8 1
Basic Thread
Length LT
1.000 1.125 1.250 1.375 1.500 1.750 2.000 2.250 2.500
Nominal
Length L
LG LB LG LB LG LB LG LB LG LB LG LB LG LB LG LB LG LB
1.50 .50 .25
1.75 .50 .25 .62 .35 .50 .19
2.00 1.00 .75 .62 .35 .50 .19 .62 .27
2.25 1.00 .75 1.12 .85 1.00 .69 .62 .27 .75 .36
2.50 1.50 1.25 1.12 .85 1.00 .69 1.12 .77 .75 .36 .75 .30
2.75 1.50 1.25 1.62 1.35 1.50 1.19 1.12 .77 .75 .36 .75 .30
3.00 2.00 1.75 1.62 1.35 1.50 1.19 1.62 1.27 1.50 1.12 .75 .30 1.00 .50
3.25 2.00 1.75 2.12 1.85 2.00 1.69 1.62 1.27 1.50 1.12 1.50 1.04 1.00 .50 1.00 .44
3.50 2.50 2.25 2.12 1.85 2.00 1.69 2.12 1.77 1.50 1.12 1.50 1.04 1.00 .50 1.00 .44 1.00 .38
4.00 3.00 2.75 2.62 2.35 2.50 2.19 2.62 2.27 2.25 1.86 2.25 1.80 2.00 1.50 1.00 .44 1.00 .38
4.50 3.50 3.25 3.12 2.85 3.00 2.69 3.12 2.77 3.00 2.62 2.25 1.80 2.00 1.50 2.00 1.44 2.00 1.38
5.00 4.00 3.75 3.62 3.35 3.50 3.09 3.62 3.27 3.00 2.62 3.00 2.54 3.00 2.50 2.00 1.44 2.00 1.38
5.50 4.12 3.85 4.00 3.69 4.12 3.77 3.75 3.36 3.75 3.30 3.00 2.50 3.00 2.44 3.00 2.38
6.00 4.62 4.35 4.50 4.19 4.62 4.27 4.50 4.12 3.75 3.30 4.00 3.50 3.00 2.44 3.00 2.38
6.50 5.00 4.69 5.12 4.77 4.50 4.12 4.50 4.04 4.00 3.50 4.00 3.44 4.00 3.38
7.00 5.50 5.19 5.62 5.27 5.25 4.86 5.25 4.80 5.00 4.50 4.00 3.44 4.00 3.38
8.00 6.62 6.27 6.00 5.62 6.00 5.54 6.00 5.50 5.00 4.44 5.00 4.38
9.00 7.62 7.27 7.00 6.62 6.75 6.30 7.00 6.50 6.00 5.44 6.00 5.38
10.00 8.00 7.62 7.75 7.30 8.00 7.50 7.00 6.44 7.00 6.38
11.00 9.25 8.80 9.00 8.50 8.00 7.44 8.00 7.38
12.00 10.25 9.80 10.00 9.50 9.00 8.44 9.00 8.38



Notes pertaining to the Thread length of Socket Head Cap Screws

  • The basic thread lengths (LT) listed directly below the nominal sizes in the above two tables represents the nominal length up to which all screws of that diameter shall be fully threaded.
  • To determine the threaded portion of the screws with a nominal length greater than LT, subtract the minimum design grip length (LG from the nominal length (L).
  • For screws over 1 inch in diameter and of nominal lengths longer than LT, the maximum grip gaging length (LG and the minimum body length (LB) of the screws shall be determined as follows.
    • LG = L - LT
    • LB = L - LTT
    • Where: L = Nominal Length
    • Where: LT = Minimum thread length tabulated below
    • Where: LTT = Maximum total thread length tabulated below




Nominal Size Min Thread Length (LT) Max Total Thread Length (LTT)
1-1/4 3.12 5.09
1-1/2 3.75 6.08


Assembly Instructions



Smith Fastener Company • 3613 East Florence Avenue, Bell, California, 90201
Phone: ( 323 ) 587-0382 • FAX: ( 323 ) 587-8712 • E-mail: [email protected]
Copyright © 2009 by Smith Fastener Company

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