Gibraltar 31333LG Steel Thumb Screw 5/16-18 Knurled

Product Description

The GIBRALTAR 31333LG is a C-12L14 steel thumb screw designed for manual clamping and adjustment applications where tool-free operation is required. It features a knurled head for secure hand-grip tightening and a swivel pad tip that pivots up to 20 degrees to accommodate angled or uneven clamping surfaces. The black oxide finish provides moderate corrosion resistance and reduces light reflection in machining and fixturing environments. At 2.985 inches overall length with a 5/16-18 UNC thread, this screw suits fixture builders, machine operators, and maintenance technicians working with standard inch-thread assemblies.

This thumb screw is commonly used in workholding fixtures, jigs, machine tool setups, and light industrial clamping applications. The swivel pad tip distributes clamping force evenly against workpiece surfaces, minimizing marring. The knurled head diameter of 1.125 inches provides enough contact surface for adequate hand torque without tools. It is a standard inch-series fastener suited for production, maintenance, and toolroom environments where frequent manual adjustments are made.

Key Features

• C-12L14 free-machining steel construction for consistent thread quality and dimensional accuracy
• Knurled head design allows tool-free tightening and loosening by hand
• Swivel pad tip pivots up to 20 degrees to conform to angled clamping surfaces
• Black oxide finish reduces surface corrosion and minimizes light glare in shop environments
• 5/16-18 UNC thread standard ensures compatibility with standard inch-thread fixtures and components
• Steel swivel pad tip provides durability under repeated clamping cycles

Compatibility

Designed as an OEM-style replacement or direct-fit component for fixtures, jigs, and clamping assemblies using 5/16-18 UNC inch-series threaded fasteners.

Installation Notes

Installation requires no special tools — thread the screw by hand into a mating 5/16-18 UNC tapped hole or threaded insert. Ensure the swivel pad tip is properly seated against the clamping surface before applying load. Do not use power tools to drive this thumb screw, as over-torquing can damage the knurled head or strip the thread. Verify thread engagement depth is sufficient for the clamping load of the application before use.