S-91385A539 1/4"-20 x 5/8" ASME B18.3, ASTM F912 Set Screws

Key Features & Benefits at a Glance

• Permanent vibration resistance with integrated Nylon Patch thread locker that eliminates the need for separate locking hardware
• Superior corrosion protection from the Black-Oxide finish on Alloy Steel, extending service life in demanding environments
• Reliable high-strength fastening backed by Rockwell C45 hardness, preventing deformation under heavy loads
• Wide operational temperature range from -50°F to 250°F, ensuring consistent performance in extreme conditions
• Precise, secure thread engagement with Class 3A UNC coarse threads that resist loosening and enable quick assembly
• Easy installation and removal using the standard 1/8" hex drive, compatible with common industrial tools
• Firm grip on components thanks to the cup point design that bites into shafts for non-slip positioning

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel set screw is engineered to solve critical industrial fastening challenges where vibration, thermal cycling, and positional accuracy are concerns. The Nylon Patch thread locker provides a permanent locking mechanism that maintains clamp force without chemical adhesives, ideal for machinery, motor assemblies, and precision equipment. Its cup point concentrates pressure to prevent shaft slippage in pulleys, gears, and collars, while the Class 3A UNC coarse thread ensures rapid installation and high resistance to cross-threading. Made from hardened Alloy Steel, it delivers durability for repetitive adjustments and high-torque applications, reducing maintenance downtime and replacement costs.

Specification Summary & Compliance

This set screw features a 1/4"-20 UNC Class 3A thread fit with coarse spacing, manufactured to ASME B18.3 specifications. It complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use in global markets. The product meets ASTM F912 standards for quality and performance.