S-90390A540 1/4"-20 x 1 1/4" Tapping Screws

Key Features & Benefits at a Glance

• Superior Thread Cutting Performance – Self-tapping Type F design with coarse UNC threads creates durable, secure threads in aluminum, brass, cast iron, and sheet metal without pre-tapped holes.
• Enhanced Corrosion Resistance – Black-phosphate steel coating provides reliable protection against rust and wear in demanding industrial environments.
• High-Torque Installation Capability – T30 Torx drive offers excellent torque transfer, reducing cam-out and driver slippage for faster, more reliable assembly.
• Flush, Professional Finish – Flat head with 82° countersink angle sits neatly flush with material surfaces, minimizing protrusion and improving aesthetics.
• Full Thread Engagement – Fully threaded 1 1/4" length ensures maximum grip and load distribution across the entire fastener for stronger assemblies.
• Simplified Installation Process – Compatible with No. 1 drill bit (0.228") for precise pilot holes, reducing installation time and improving accuracy.
• Wide Material Compatibility – Specifically engineered for use in aluminum, brass, cast iron, and sheet metal, providing versatile fastening solutions across multiple industries.

Professional Applications & Engineering Value

These 1/4"-20 thread cutting screws deliver exceptional value in metal fabrication and assembly operations where creating strong, reliable threads in base materials is critical. The black-phosphate steel construction combined with Type F thread cutting design eliminates the need for separate tapping operations, significantly reducing labor time and costs. The T30 Torx drive system prevents tool slippage during high-torque installation, ensuring consistent seating and reducing fastener damage. With their 82° countersink flat head profile, these screws provide a clean, flush finish that meets professional standards in applications ranging from HVAC ductwork to machinery assembly. The coarse UNC threading and fully threaded shank maximize holding power in both soft metals and thicker materials, making them ideal for construction, automotive, and industrial equipment applications where vibration resistance and long-term reliability are paramount.

Specification Summary & Compliance

These thread cutting tapping screws feature precision 1/4"-20 UNC coarse threads with standard Class 2A thread tolerances for consistent performance. The flat head design incorporates an 82° countersink angle for proper seating in standard countersunk holes. Manufactured to industry standards for Type F tapping screws, these fasteners are fully threaded with a blunt tip and right-hand thread direction. The black-phosphate surface treatment provides corrosion resistance while maintaining compliance with industrial fastener specifications. Recommended for use with No. 1 drill bit (0.228" diameter) for optimal pilot hole preparation in various metal substrates.