Gibraltar 831405-G Shoulder Screw 3/8 in Black Oxide Steel

Product Description

The GIBRALTAR 831405-G is a steel shoulder screw with a black oxide finish, designed for precision fastening applications that require a fixed bearing surface or pivot point. The shoulder measures 0.375 inches in diameter and 0.5 inches in length, providing a consistent cylindrical surface for bushings, bearings, or linkage components to ride against. The threaded portion is 5/16-18 UNC, driven by a 3/16-inch hex socket. Material grade 1137 steel gives this fastener good machinability and adequate strength for mechanical assemblies. Maintenance technicians and mechanical assemblers typically use shoulder screws in industrial equipment, fixtures, and machinery where controlled clearance fits are required.

This shoulder screw is suited for use in jigs, fixtures, conveyor systems, and general industrial machinery where a precision shoulder is needed to guide or retain a component. The black oxide finish provides mild corrosion resistance and reduces light reflection on the fastener surface. The hex socket drive allows installation in tight clearances where a standard wrench would not fit. It is sold individually with a minimum order quantity of 2 units.

Key Features

• Shoulder diameter of 0.375 inches provides a precise bearing surface for bushings and linkage components
• 0.5-inch shoulder length suits shallow mounting applications and thin-plate assemblies
• 5/16-18 UNC thread engages standard tapped holes in steel and aluminum components
• 3/16-inch hex socket drive allows installation with a standard Allen wrench in confined spaces
• Black oxide finish on grade 1137 steel offers mild corrosion resistance and a low-glare surface
• Head diameter of 0.5625 inches and head height of 0.25 inches provide a low-profile clamping surface

Compatibility

Designed as a standard shoulder screw for use in industrial fixtures, mechanical assemblies, and equipment requiring a 3/8-inch shoulder diameter with 5/16-18 UNC threading.

Installation Notes

Installation requires a 3/16-inch hex key or Allen driver. Ensure the mating tapped hole is clean and dimensionally correct for 5/16-18 UNC threads before installation. Do not overtighten, as the shoulder — not the thread — is the functional bearing surface; excessive torque can deform the shoulder fit. Follow applicable machinery maintenance procedures and equipment manufacturer guidelines when replacing fasteners in load-bearing assemblies.