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Square Head Set Screw

Selected Square Head Set Screw Cup Point Plain1-8 X 5 1/2 Case Hardened Square Head Set Screw Cup Point
Square Head Set Screw Cup Point Plain1-8 X 5 1/2 Case Hardened Square Head Set Screw Cup Point

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.

 

Products

Dimensional Specifications

Finished bolt and cap screw dimensions
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
  1. All dimensions are in inches.

Governing Standards

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.

Alloy Steel Square Head Set Screw
Alloy Steel Square Head Set Screw requires no material marking