Holo-krome 78066 Hex Socket Cap Screw 1/4-20 Unc 18-8 Ss

Product Description

The HOLO-KROME 78066 is a hex socket cap screw designed for secure mechanical fastening in applications requiring a recessed-drive, low-profile head. It features a 1/4-20 UNC thread and a 1-1/2 inch length under head with partial threading. The 3/16 inch hex socket drive accepts a standard hex key or Allen wrench. Constructed from 18-8 stainless steel with a bright, uncoated finish, this fastener offers solid corrosion resistance in moderate environments. It meets ASME B18.3 and ASTM F837 standards. Machinists, millwrights, HVAC technicians, and general tradespeople use these screws where a flush or recessed fastener head is required.

This screw is suited for light to medium-duty mechanical assemblies across residential, commercial, and industrial settings. Common applications include equipment panel fastening, bracket mounting, pump and motor assembly, and general sheet metal or structural work where a clean fastener profile is needed. The 1/4-20 UNC thread is a widely used standard that fits a broad range of tapped holes and threaded inserts. The partial threading allows for shank engagement in clearance holes before the threaded section bites, which can improve joint alignment during installation.

Key Features

• 1/4-20 UNC thread for compatibility with standard tapped holes and inserts
• 1-1/2 inch length under head with partial threading for shank clearance engagement
• 3/16 inch hex socket drive — requires standard hex key or Allen driver
• 18-8 stainless steel construction provides corrosion resistance in moderate environments
• Bright, uncoated finish — no risk of coating interference in precision fits
• Meets ASME B18.3 and ASTM F837 fastener standards

Compatibility

Designed as an OEM-style or replacement hex socket cap screw for any application using a 1/4-20 UNC partially threaded socket head cap screw with a 1-1/2 inch length under head. Fits standard tapped holes conforming to 1/4-20 UNC thread specifications.

Installation Notes

Install using a 3/16 inch hex key or Allen driver; do not use an undersized key as it may round the socket. Ensure the tapped hole is clean and free of debris before threading. Apply appropriate thread lubricant or anti-seize compound if installing in an environment prone to galling, which is common with stainless steel fasteners. Do not exceed the torque rating for the fastener size and material grade — consult a standard fastener torque table for 1/4-20 18-8 stainless specifications.