Gibraltar 31331SG Steel Thumb Screw 5/16-18 Knurled Head

Product Description

The GIBRALTAR 31331SG is a steel thumb screw designed for tool-free clamping, adjusting, and securing applications in industrial, mechanical, and fixture-assembly work. It features a knurled head profile that allows firm finger-tightening without a driver. The 5/16-18 UNC thread provides reliable engagement in standard tapped holes. A swivel pad tip with a 20-degree swivel angle distributes clamping force evenly across workpiece surfaces and helps prevent marring. The black oxide finish provides mild corrosion resistance. Overall length is 1.875 inches, with a head diameter of 1.125 inches and a head height of 0.375 inches.

This thumb screw suits applications where repeated hand adjustment is required, such as fixturing, jigs, machine guards, enclosure panels, and tooling setups. The swivel pad tip is well suited for clamping against angled or irregular surfaces without scoring the material. The without-shoulder body design allows full thread engagement into the receiving component. Machinists, toolmakers, maintenance technicians, and assembly workers are the primary installers.

Key Features

• 5/16-18 UNC thread for compatibility with standard inch-series tapped holes
• Knurled head allows secure finger-tightening without tools
• Swivel pad tip with 20-degree swivel angle accommodates angled clamping surfaces
• Steel tip material provides durability at the contact point
• Black oxide finish for mild corrosion and wear resistance
• Without-shoulder design for maximum thread engagement depth

Compatibility

Designed for use in standard 5/16-18 UNC tapped holes in fixtures, jigs, machine guards, and general industrial assemblies requiring tool-free hand adjustment.

Installation Notes

Thread engagement should be sufficient to handle the applied clamping load before tightening by hand. Do not use power tools to drive this thumb screw, as the knurled head is designed for hand operation only and over-torquing can strip the thread or damage the swivel pad. Inspect the swivel pad for wear or debris before each use to ensure even force distribution on the workpiece.