Holo-krome 77474 Hex Socket Cap Screw 1/4-28 Unf

Product Description

The HOLO-KROME 77474 is a hex socket cap screw designed for high-strength fastening applications where a clean, recessed drive is required. It features a 1/4-28 UNF thread size with a 2-1/2 inch length under head and is partially threaded along the shank. The 3/16 inch hex drive accepts a standard hex key or Allen wrench. Constructed from alloy steel with a black oxide coating, this fastener delivers solid mechanical strength and moderate corrosion resistance. It meets ASME B18.3 and ASTM A574 standards, making it suitable for precision assemblies and load-bearing connections across a range of industrial and mechanical applications.

This screw is used in mechanical assemblies, machine components, tooling fixtures, and structural joints where a flush or low-profile fastener head is preferred. The fine 28-thread-per-inch pitch provides tighter clamping force and better resistance to loosening under vibration compared to coarse-thread equivalents. Typical installers include millwrights, machinists, and maintenance technicians working in manufacturing, industrial equipment, and precision mechanical systems. The black oxide finish is suited for interior or lightly controlled environments where aesthetic uniformity or reduced light reflection is needed.

Key Features

• 1/4-28 UNF fine thread for increased clamp load and vibration resistance
• 2-1/2 inch length under head with partial threading along the shank
• 3/16 inch hex socket drive for use with standard hex key tools
• Alloy steel construction meets ASTM A574 high-strength requirements
• Black oxide coating provides a uniform, low-reflectance finish
• Conforms to ASME B18.3 dimensional standards

Compatibility

Designed as a standard ASME B18.3 hex socket cap screw suitable for tapped holes accepting 1/4-28 UNF threads in alloy steel, stainless, or aluminum components.

Installation Notes

Installation is performed using a 3/16 inch hex key or T-handle Allen wrench. Ensure the mating tapped hole is clean and free of debris before driving the fastener. Apply thread-locking compound where vibration loosening is a concern. Do not exceed the rated torque range for 1/4-28 alloy steel cap screws as specified in applicable mechanical standards.