Value Collection -40871 Button Socket Cap Screw 1/4-28

Product Description

The VALUE COLLECTION -40871 is a fully threaded button socket cap screw designed for applications requiring a low-profile fastener head with high tensile strength. Sized at 1/4-28 UNF with a 5/8-inch length under the head, this screw is machined from alloy steel and finished with a black oxide coating to provide moderate corrosion resistance and a consistent dark appearance. The 5/32-inch hex socket drive accepts a standard ball-end or straight hex key. Hardness is rated at 36-43 HRC, conforming to ANSI/ASME B18.3 and ASTM F835 standards. Thread fit class is 3A, right-hand direction. This fastener is used by machinists, millwrights, and general mechanical trades.

The -40871 button cap screw is suited for machine assembly, fixture building, and panel or guard attachment where a rounded, low-profile head is needed to clear adjacent components or reduce snag points. The fine 1/4-28 thread pitch provides strong thread engagement in tapped metal components and is common in precision mechanical assemblies, jigs, and equipment housings. The black oxide finish makes it a common choice where a non-reflective appearance is required alongside reasonable lubricity during installation.

Key Features

• Fully threaded 1/4-28 UNF fine-thread configuration for strong engagement in tapped metal
• Alloy steel construction with 36-43 HRC hardness per ASTM F835
• Black oxide coating for moderate corrosion resistance and non-reflective finish
• Low-profile button head reduces snag risk in clearance-critical assemblies
• 5/32-inch hex socket drive compatible with standard hex keys and ball drivers
• Conforms to ANSI/ASME B18.3 dimensional standards

Compatibility

Designed as an OEM-style replacement or direct-use fastener for applications requiring a 1/4-28 UNF fully threaded button socket cap screw conforming to ANSI/ASME B18.3 and ASTM F835.

Installation Notes

Installation is performed with a 5/32-inch hex key or ball-end driver; ensure the drive tool is fully seated before applying torque to avoid rounding the socket. Always verify the mating tapped hole is the correct 1/4-28 UNF thread form and is clean and free of debris before threading. Black oxide fasteners benefit from a light application of thread lubricant or anti-seize when used in ferrous assemblies subject to moisture. Do not exceed the rated hardness class by substituting this fastener in applications specifying higher-grade cap screws without engineering review.