S-91830A105 4-40 x 1/2" Thumb Screws

Key Features & Benefits at a Glance

• Enhanced Grip & Fast Operation: Knurled round head provides superior manual handling, reducing tool dependency and speeding up assembly/disassembly in tight spaces.
• Exceptional Corrosion Resistance: Made from 18-8 Stainless Steel, offering reliable performance in humid, chemical, or outdoor environments without rusting.
• High Mechanical Strength: With 80,000 psi tensile strength and Rockwell B83 hardness, it withstands heavy loads and repeated use without stripping or deformation.
• Precision Thread Fit: Class 2A thread fit ensures smooth engagement and consistent clamping force, minimizing cross-threading risks in 4-40 UNC coarse threading applications.
• Full Thread Engagement: Fully threaded 1/2" length allows for maximum adjustability and secure fastening across varying material thicknesses.
• Regulatory Compliance: Meets RoHS 3 and REACH standards, ensuring safe use in regulated industries like electronics, automotive, and machinery.
• Versatile Collar Design: Integrated collar (1/4" diameter, 1/8" height) provides added stability and prevents over-insertion in panel or chassis mounts.

Professional Applications & Engineering Value

This 4-40 UNC thumb screw is engineered to address common industrial challenges such as frequent access needs and exposure to corrosive elements. The 18-8 Stainless Steel construction delivers inherent resistance to oxidation and chemicals, making it ideal for electronic enclosures, instrumentation panels, and machinery guards where durability is critical. The knurled head offers a non-slip grip, enabling quick manual adjustments without specialized tools—reducing downtime in maintenance-heavy environments. Combined with coarse UNC threading and a Class 2A fit, it ensures reliable engagement in softer materials or pre-tapped holes, preventing loosening under vibration. Its fully threaded design and robust 80,000 psi tensile strength provide consistent clamping force, securing components in aerospace, automotive, and telecom assemblies with precision.

Specification Summary & Compliance

This thumb screw adheres to UNC thread standards with a Class 2A thread fit for precise dimensional accuracy and smooth installation. Manufacturing complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring the absence of hazardous substances. Key specs include a 1/2" length, 4-40 coarse thread, right-hand direction, and full threading for uniform performance. The screw meets general industry norms for stainless steel fasteners in mechanical and electrical applications.