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Square Head Set Screw

Square head set screws, also known as jack bolts, are fully threaded fasteners with a square head and most commonly, a cup point, though other types of points are available. Square head set screws are manufactured from alloy steel for maximum strength, as well as high resistance to galling, wear and fatigue. They have a large wrenching area that provides positive gripping for a hand wrench. They are ideal for holding pulleys, collars, and other machinery shafts where fine adjustments are necessary. Dimensional specifications are governed by ASME B18.6.2.

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Governing Standards
Dimensional Specifications

Dimensional Specifications

Dimensional SpecificationsAlloy Steel Square Head Set Screw

Per ASME B18.6.2-1998
Size	Nominal	UNC	UNF	F		G		H		K		S	U	W
				Width Across Flats		Width Across Corners		Head Height		Neck Relief Diameter		Neck Relief Fillet Radius	Neck Relief Width	Head Radius
				Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Min
#10	0.1900	24	32	0.1880	0.1800	0.2650	0.2470	0.1480	0.1340	0.1450	0.1400	0.0270	0.0830	0.4800
1/4	0.2500	20	28	0.2500	0.2410	0.3540	0.3310	0.1960	0.1780	0.1850	0.1700	0.0320	0.1000	0.6200
5/16	0.3125	18	24	0.3120	0.3020	0.4420	0.4150	0.2450	0.2240	0.2400	0.2250	0.0360	0.1110	0.7800
3/8	0.3750	16	24	0.3750	0.3620	0.5300	0.4970	0.2930	0.2700	0.2940	0.2790	0.0410	0.1250	0.9400
7/16	0.4375	14	20	0.4380	0.4230	0.6190	0.5810	0.3410	0.3150	0.3450	0.3300	0.0460	0.1430	1.0900
1/2	0.5000	13	20	0.5000	0.4840	0.7070	0.6650	0.3890	0.3610	0.4000	0.3850	0.0500	0.1540	1.2500
9/16	0.5625	12	18	0.5620	0.5450	0.7950	0.7480	0.4370	0.4070	0.4540	0.4390	0.0540	0.1670	1.4100
5/8	0.6250	11	18	0.6250	0.6060	0.8840	0.8330	0.4850	0.4520	0.5070	0.4920	0.0590	0.1820	1.5600
3/4	0.7500	10	16	0.7500	0.7290	1.0600	1.0010	0.5820	0.5440	0.6200	0.6050	0.0650	0.2000	1.8800
7/8	0.8750	9	14	0.8750	0.8520	1.2370	1.1700	0.6780	0.6350	0.7310	0.7160	0.0720	0.2220	2.1900
1	1.0000	8	14	1.0000	0.9740	1.4140	1.3370	0.7740	0.7260	0.8380	0.8230	0.0810	0.2500	2.5000
1 1/8	1.1250	7	12	1.1250	1.0960	1.5910	1.5050	0.8700	0.8170	0.9390	0.9140	0.0920	0.2830	2.8100
1 1/4	1.2500	7	12	1.2500	1.2190	1.7680	1.6740	0.9660	0.9080	1.0640	1.0390	0.0920	0.2830	3.1200
1 3/8	1.3750	6	12	1.3750	1.3420	1.9450	1.8430	1.0630	1.0000	1.1590	1.1340	0.1090	0.3330	3.4400
1 1/2	1.5000	6	12	1.5000	1.4640	2.121	2.0100	1.1590	1.0910	1.2840	1.2590	0.1090	0.3330	3.7500

All dimensions are in inches.

Square Head Set Screw

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Diameter Length Threading Item # Availability Price Quantity UOM

5/16

1/2

Full

SHSA0310050

In Stock

$0.23486/EA

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5/16-18 X 1/2 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

$0.23486/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$0.23486/EA
1180	$0.22261/EA
4720	$0.20234/EA
21240	$0.13769/EA

5/16

3/4

Full

SHSA0310075

In Stock

$0.30607/EA

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5/16-18 X 3/4 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

$0.30607/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$0.30607/EA
720	$0.29012/EA
2880	$0.26369/EA
12960	$0.17944/EA

5/16

Full

SHSA0310100

In Stock

$0.19236/EA

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5/16-18 X 1 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

$0.19236/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$0.19236/EA
530	$0.18233/EA
2090	$0.16572/EA
9400	$0.11277/EA

5/16

1 1/4

Full

SHSA0310125

In Stock

$0.28332/EA

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5/16-18 X 1 1/4 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

$0.28332/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$0.28332/EA
410	$0.26855/EA
1640	$0.24409/EA
7350	$0.1661/EA

5/16

1 1/2

Full

SHSA0310150

In Stock

$0.34446/EA

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5/16-18 X 1 1/2 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

$0.34446/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$0.34446/EA
340	$0.32651/EA
1340	$0.29677/EA
6010	$0.20195/EA

5/16

Full

SHSA0310200

In Stock

$0.31136/EA

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5/16-18 X 2 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

$0.31136/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$0.31136/EA
250	$0.29513/EA
980	$0.26825/EA
4390	$0.18254/EA

5/16

Full

SHSA0310300

In Stock

$1.00543/EA

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5/16-18 X 3 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

$1.00543/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$1.00543/EA
170	$0.95301/EA
650	$0.86622/EA
2890	$0.58945/EA

ASME B18.6.2	Covers the complete general and dimensional data for the various styles of slotted head cap screws and square head and slotted headless set screws recognized as American National Standard.
ASME B1.1 UNC & UNF Class 2A	Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.

Square Head Set Screw

Technical Data

Governing Standards

Governing StandardsAlloy Steel Square Head Set Screw

Dimensional Specifications

Dimensional SpecificationsAlloy Steel Square Head Set Screw

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Width Across Flats

5/16-18 X 1/2 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

5/16-18 X 3/4 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

5/16-18 X 1 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

5/16-18 X 1 1/4 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

5/16-18 X 1 1/2 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

5/16-18 X 2 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT

5/16-18 X 3 CASE HARDENED SQUARE HEAD SET SCREW CUP POINT