Value Collection 101339PR Set Screw 1/4-28 X 5/16 in Cup Point

Product Description

The VALUE COLLECTION 101339PR is a 1/4-28 UNF cup point set screw manufactured from Grade 8 alloy steel. At 5/16 inches in overall length, this headless fastener is driven with a 1/8-inch hex key and seats firmly into a mating bore via its cup point, which bites into the shaft surface to resist rotational and axial movement. Conforming to ASME/ANSI B18.3 and ASTM F912 standards, this set screw is suited for applications where a flush or recessed fastener is required and holding strength is a priority. Machinists, maintenance technicians, and assemblers working in industrial and mechanical environments are the typical installers.

This set screw is commonly used in mechanical assemblies where a collar, pulley, sprocket, knob, or similar component must be locked onto a shaft without a protruding fastener head. The fine 1/4-28 UNF thread pitch provides precise engagement and is well matched to applications requiring vibration resistance or fine adjustment. Typical use cases include motor shaft collars, gear hubs, and valve stems in both light industrial and OEM manufacturing contexts. This SKU is sold individually but carries a minimum order quantity of 100 pieces.

Key Features

• 1/4-28 UNF fine thread for precise engagement and improved vibration resistance
• Cup point geometry bites into shaft surface for firm rotational and axial holding
• Grade 8 alloy steel construction provides high tensile and torsional strength
• 1/8-inch hex drive allows installation in confined spaces with a standard hex key
• Meets ASME/ANSI B18.3 and ASTM F912 fastener standards
• Headless design sits flush or below the workpiece surface

Compatibility

Designed as a standard 1/4-28 UNF cup point set screw per ASME/ANSI B18.3, suitable for use in any application that accepts this thread size, point type, and drive specification.

Installation Notes

Installation is performed by machinists or mechanical technicians using a 1/8-inch hex key or Allen wrench. Ensure the mating bore is properly tapped to 1/4-28 UNF before installation. De-energize and lock out any rotating equipment before installing or removing set screws on live shafts. Do not exceed the rated torque capacity of the screw or the tapped bore material, and inspect threads for damage before reuse.