S-91381A539 1/4"-20 x 5/8" ASME B18.3 Set Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating on alloy steel, extending service life in harsh industrial environments
• Exceptional thread precision with Class 3A UNC coarse threads ensuring reliable, vibration-resistant fastening in high-stress applications
• Surface protection from the integrated brass soft tip that prevents damage to mating components during installation and adjustment
• High torque capability through the 1/8" hex drive design, allowing secure installation in confined headless applications
• Consistent mechanical performance with Rockwell C28 hardness providing optimal balance of strength and durability
• Regulatory compliance assurance meeting ASME B18.3 specifications and environmental standards including RoHS 3 and REACH
• Versatile right-hand threading with standard 1/4"-20 configuration for broad compatibility across industrial equipment and machinery

Professional Applications & Engineering Value

This black-oxide alloy steel set screw delivers critical engineering solutions for permanent positioning applications where vibration resistance and surface protection are paramount. The Class 3A UNC coarse thread configuration provides superior holding power in soft materials and high-vibration environments, while the brass soft tip eliminates galling and damage to precision shafts, collars, and gears. Engineered with Rockwell C28 hardness, it maintains dimensional stability under repeated adjustments in industrial machinery, automotive assemblies, and power transmission systems. The headless hex drive design enables flush mounting in space-constrained applications, making it ideal for securing pulleys, gears, and knobs where protruding fasteners are unacceptable.

Specification Summary & Compliance

This set screw features precision 1/4"-20 UNC Class 3A threads with coarse thread spacing, manufactured to ASME B18.3 dimensional standards. The 5/8" length and 0.25" thread diameter maintain tight tolerances for consistent performance. Compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring suitability for global industrial applications. The Rockwell C28 hardness provides optimal mechanical properties for demanding fastening requirements.