Capscrews are closely controlled to meet the dimensions of ASME/ANSI B18.2.1. Hex Head Capscrews areproportioned and toleranced to assure full and proper loading when assembled into a tapped hole. A washerface is provided under the head to provide a bearing surface when tightened. Unlike bolts, which have muchlooser tolerances and allow the body to be larger than the nominal diame-ter, capscrews have a body which is never larger than the nominal diameterto ensure fit-up into tapped holes without counterboring. The end of the cap-screw is chamfered to aid in inserting into a tapped hole. Our capscrews are100% made in America with raw material rolled and melted in the U.S.A. Theyare cold formed on precision high speed formers, utilizing in-process quality sys-tems, and have full traceability from raw material to each box of fasteners.Chemical and physical certifications are always available. Nucor Fastener Divisionis QS9000 and ISO9002 Registered, and our laboratory is A2LA Accredited.

SAE vs. ASTM SpecificationsWith very minor differences, the SAE Grade Capscrews have an equivalent version inthe ASTM standards. The Grade 2 Capscrew is comparable to an ASTM A307 Grade A, while the Grade 5Capscrew is the same as the ASTM A449, and the Grade 8 Capscrew has the same strength as the ASTM A354Grade BD. For those needing either specification requirement, we can dual certify our Grade 5 and Grade 2Capscrews to SAE and ASTM standards. Our SAE Grade 8 and ASTM Grade BD Capscrews are identical,however, ASTM recently instituted a requirement to stamp “BD” on the head of the capscrew; therefore, SAEGrade 8 and Grade BD Capscrews cannot be dual certified without “BD” stamped on the head of the capscrew.This is because SAE permits plain carbon 1541 grade steel for small diameter product, while ASTM requiresalloy steel. Nucor Fastener Division only uses alloy steel for Grade 8 Capscrews.

Mechanical PropertiesThe mechanical properties of finished capscrews are covered in the Society of Automotive Engineers (SAE)J429, “Mechanical and Material Requirements for Externally Threaded Fasteners Specification”. This specifica-tion covers the materials, manufacturing methods, mechanical properties, and testing requirements for cap-screws. Grade 2 (A307A) Capscrews are lower strength fasteners made from low carbon steel which achievesits strength primarily from cold forming. Grade 5 (A449) Capscrews are medium strength fasteners that achievetheir strength from a quench and temper heat treatment. Grade 8 Capscrews (A354 GR BD) are the higheststrength of standard inch series capscrews and are made from alloy steels. They also achieve their strength froma quench and temper heat treatment. Standard mechanical tests are performed in our A2LA (AmericanAssociation for Laboratory Accreditation) Accredited Laboratory.

Grade Identification

nn nn nn nn

307A

SAE J429 Grade 2ASTM A449 Type 1SAE J429 Grade 5 SAE J429 Grade 8

ASTM A307AGrade 2

CAPSCREWS

TDS-009A 2-1-01

POST OFFICE BOX 6100 • ST. JOE, INDIANA 46785PHONE: (800) 955-6826 OR (260) 337-1626 FAX: (260) 337-1726 WEB SITE: www.nucor-fastener.com

This Technical Data Sheet is subject to change without prior notification.

CAPSCREWS

1/45/163/8

7/16

1/29/165/83/47/81

1-1/81-1/41-3/8

1-1/2

0.25000.31250.37500.4375

0.50000.56250.62500.75000.8750

1.00001.12501.25001.3750

1.5000

0.25000.31250.37500.4375

0.50000.56250.62500.75000.8750

1.00001.12501.25001.3750

1.5000

0.24500.30650.36900.4305

0.49300.55450.61700.74100.8660

0.99001.11401.23901.3630

1.4880

7/161/2

9/165/8

3/413/1615/161-1/8

1-5/16

1-1/21

-11/161-7/8

2-1/16

2-1/4

0.4380.5000.5620.625

0.7500.8120.9381.1251.312

1.5001.6881.8752.062

2.230

0.4280.4890.5510.612

0.7360.7980.9221.1001.285

1.4691.6311.8121.994

2.175

0.5050.5770.6500.722

0.8660.9381.0831.2991.516

1.7321.9492.1652.382

2.598

0.4880.5570.6280.698

0.8400.9101.0511.2541.465

1.6751.8592.0662.273

2.480

5/3213/6415/649/32

5/1623/6425/6415/3235/64

39/6411/1625/3227/32

1-5/16

0.1630.2110.2430.291

0.3230.3710.4030.4830.563

0.6270.7180.8130.878

0.974

0.1500.1950.2260.272

0.3020.3480.3780.4550.531

0.5910.6580.7490.810

0.902

0.1060.1400.1600.195

0.2150.2500.2690.3240.378

0.4160.4610.5300.569

0.640

0.7500.8751.0001.125

1.2501.3751.5001.7502.000

2.2502.5002.7503.000

3.250

1.0001.1251.2501.375

1.5001.6251.7502.0002.250

2.5002.7503.0003.250

3.500

0.2500.2780.3120.357

0.3850.4170.4550.5000.556

0.6250.7140.7140.833

0.833

0.0100.0110.0120.013

0.0140.0150.0170.0200.023

0.0260.0290.0330.036

0.039

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Table 4 Dim

ensions of Hex Capscrew

s

(AN

SI B18.2.1)

Distributed By:

Applications

Capscrews can be used in tapped holes or with a nut (like a bolt). Most designs with capscrews where a clampload is needed require the capscrew to be tightened to 75% of the proof load for a safe working range. Shear

Table 2 - Proof Load and Tensile Strength Requirements

Table 1 - Mechanical Properties of Capscrews

Suggested Starting Torque Values

All torque/tension relationships should be viewed with a cautious eye since no one table can indicate the rangeof conditions expected to be experienced by a fastener. Torque is only an indirect indication of tension. Thetorque value to use in an application is best obtained by using a calibrated torque wrench (or transducer) anda Skidmore-Wilhelm type load indicating device to equate actual torque to desired tension. Nearly all of thetorque/tension tables which have been developed, including the one shown in Table 3, are based on the fol-lowing formula:

T = (k*d*P)/12 where T = Torque (ft-lbs), d = nominal diameter (inches), P = Tension (lbs), and k is the “torquecoefficient” or “nut factor” (dimensionless)

The value of k is a dimensionless “fudge factor” which includes variables such as friction, thread conditions, etc.The value of k can range from 0.10 for a well lubricated connection to greater than 0.30 for a rusted assem-bly. Normally, k is approximately 0.20 for plain steel (increase by about 10% for zinc plated and decrease byabout 25% for parts which have been well lubricated). The torques shown below represent starting values forplain capscrews (k = 0.20) at 60% - 90% of the proof load tension:

1/4 - 201/4 - 28

5/16 - 185/16 - 24

3/8 - 163/8 - 24

7/16 - 147/16 - 20

1/2 - 131/2 - 20

9/16 - 129/16 - 18

5/8 - 115/8 - 183/4 - 103/4 - 167/8 - 9

7/8 - 141 - 8

1 - 141-1/8 - 7

1-1/8 - 121-1/4 - 7

1-1/4 - 12

0.03180.03640.05240.05800.07750.08780.10630.11870.14190.15990.18200.20300.22600.25600.33400.37300.46200.50900.60600.67900.76300.85600.96901.0730

1,049 - 1,5741,201 - 1,8021,729 - 2,5941,914 - 2,8712,558 - 3,8682,897 - 4,3463,508 - 5,2623,917 - 5,8764,683 - 7,0245,277 - 7,9156,006 - 9,009

6,699 - 10,0497,458 - 11,1878,448 - 12,672

11,022 - 16,53312,309 - 18,46415,246 - 22,86916,797 - 25,19619,998 - 29,99722,407 - 33,61125,179 - 37,76928,248 - 42,37231,977 - 47,96635,409 - 53,114

4 - 75 - 8

9 - 1410 - 1516 - 2418 - 2726 - 3829 - 4339 - 5944 - 6656 - 8463 - 94

78 - 11788 - 132

138 - 207154 - 231222 - 334245 - 367333 - 500373 - 560472 - 708530 - 794666 - 999

738 - 1,107

1,622 - 2,4331,856 - 2,7852,672 - 4,0092,958 - 4,4373,953 - 5,9294,478 - 6,7175,421 - 8,1326,054 - 9,081

7,237 - 10,8558,155 - 12,2329,282 - 13,923

10,353 - 15,53011,526 - 17,28913,056 - 19,58417,034 - 25,55119,023 - 28,53523,562 - 35,34325,959 - 38,93930,906 - 46,35934,629 - 51,94433,877 - 50,81638,006 - 57,01043,024 - 64,53547,641 - 71,462

7 - 108 - 12

14 - 2115 - 2325 - 3728 - 4240 - 5944 - 6660 - 90

68 - 10287 - 13197 - 146

120 - 180136 - 204213 - 319238 - 357344 - 515379 - 568515 - 773577 - 866635 - 953

713 - 1,069896 - 1,344993 - 1,489

2,290 - 3,4342,621 - 3,9313,773 - 5,6594,176 - 6,2645,580 - 8,3706,322 - 9,482

7,654 - 11,4808,546 - 12,820

10,217 - 15,32511,513 - 17,26913,104 - 19,65614,616 - 21,92416,272 - 24,40818,432 - 27,64824,048 - 36,07226,856 - 40,28433,264 - 49,89636,648 - 54,97243,632 - 65,44848,888 - 73,33254,936 - 82,40461,632 - 92,448

69,768 - 104,65277,256 - 115,884

10 - 1411 - 1620 - 2922 - 3335 - 5240 - 5956 - 8462 - 93

85 - 12896 - 144

123 - 184137 - 206170 - 254192 - 288301 - 451336 - 504485 - 728534 - 802

727 - 1,091815 - 1,222

1,030 - 1,5451,156 - 1,7331,454 - 2,1801,610 - 2,414

NOMINALDIAMETERAND TPI(INCHES)

THREADSTRESSAREA

(SQ-IN)

CLAMP LOAD60-90%PROOF

(POUNDS)

SAE GRADE 2 CAPSCREWS SAE GRADE 5 CAPSCREWS SAE GRADE 8 CAPSCREWS

TIGHTENINGTORQUE(FT-LBS)

CLAMP LOAD60-90%PROOF

(POUNDS)

TIGHTENINGTORQUE(FT-LBS)

CLAMP LOAD60-90%PROOF

(POUNDS)

TIGHTENINGTORQUE(FT-LBS)

Table 3 - Suggested Torque Values and Clamp Loads for Grades 2, 5, & 8 Capscrews

strength of a capscrew loaded in single shear through the threads is about 60% of the ultimate tensile strength,so working loads should be lower than this breaking strength. The fatigue strength of capscrews as measuredby the endurance limit will vary widely depending upon the amplitude, frequency, and type of applied load.Endurance limits of 10-20% of the tensile strength have been reported for high strength capscrews.