S-91404A552 1/4"-20 x 2 1/2" Thumb Screws

Key Features & Benefits at a Glance

• Tool-free installation and adjustment with large 1 3/8" wing head for maximum hand grip, even with gloves
• Superior corrosion resistance from zinc-plated iron construction, extending service life in industrial environments
• Quick assembly and reliable fastening with 1/4"-20 UNC coarse threading that resists cross-threading
• Consistent thread engagement ensured by Class 2A thread fit tolerance for precise mechanical assemblies
• Full-length threading provides maximum grip along the entire 2 1/2" shaft for secure fastening in deep applications
• Right-hand thread direction follows standard convention for intuitive installation by maintenance personnel
• Compliance with environmental regulations including RoHS 3 and REACH for use in regulated industries

Professional Applications & Engineering Value

This zinc-plated iron thumb screw delivers exceptional value in applications requiring frequent access or adjustment without tools. The 1 3/8" wing head design provides substantial leverage for hand-tightening, making it ideal for electrical enclosures, machinery guards, and access panels where tools may be misplaced or impractical. The 1/4"-20 UNC coarse thread configuration ensures rapid installation and removal while resisting vibration-induced loosening. The zinc plating offers reliable corrosion protection in manufacturing facilities, outdoor equipment, and industrial environments where moisture and chemicals are present. With full threading along the 2 1/2" length, this fastener maintains consistent clamping force in deep-set applications, providing engineers with a reliable solution for maintenance-friendly assemblies.

Specification Summary & Compliance

This thumb screw features 1/4"-20 UNC coarse threading with Class 2A thread fit tolerance for precision assembly. The 7/16" head diameter maintains dimensional consistency with minimal tolerance variation. Manufactured from zinc-plated iron with right-hand thread direction and fully threaded design. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations for use in industrial applications requiring regulatory adherence.