S-91381A542 1/4"-20 x 1" ASME B18.3 Set Screws

Key Features & Benefits at a Glance

• Superior Grip & Precision: Class 3A thread fit ensures tight tolerances and reliable, vibration-resistant fastening in demanding applications.
• Exceptional Durability: Made from Black-Oxide Alloy Steel with a Rockwell C28 hardness for high strength and excellent corrosion resistance.
• Surface Protection: Integrated brass soft tip prevents marring and damage to expensive or finished components during assembly and adjustment.
• Secure & Low-Profile Installation: The headless design with a 1/8" hex drive allows for flush mounting and access in confined spaces.
• Robust Coarse Threading: 1/4"-20 UNC coarse thread provides rapid installation and superior holding power in a wide range of materials.
• Industry Standard Compliance: Manufactured to meet ASME B18.3 specifications, guaranteeing consistent quality and interchangeability.
• Environmental & Regulatory Safety: Fully compliant with RoHS 3 and REACH regulations for safe use in global industrial markets.

Professional Applications & Engineering Value

This 1/4"-20 UNC set screw is engineered to solve critical challenges in precision assembly and motion control systems. The Black-Oxide Alloy Steel construction provides the necessary Rockwell C28 hardness to withstand high shear forces and repetitive stress in pulleys, gears, and collars. Its defining feature, the non-marring brass soft tip, is essential for applications involving shafts and precision-machined components, eliminating surface galling and ensuring that expensive parts remain undamaged during clamping. The headless design and hex drive make it ideal for space-constrained environments where a flush finish is required. This combination of a Class 3A thread fit and robust material makes it a reliable choice for maintaining permanent alignment and preventing slippage in high-vibration industrial machinery.

Specification Summary & Compliance

This set screw features a 1/4"-20 UNC coarse thread with a precision Class 3A thread fit for superior engagement. It is manufactured from Alloy Steel with a Black-Oxide surface treatment and includes a brass tip (0.063" length, 1/8" diameter). The product conforms to the ASME B18.3 standard and is verified to be RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant.