Gibraltar 31344SG Steel Thumb Screw 3/8-16 Knurled

Product Description

The GIBRALTAR 31344SG is a steel thumb screw with a 3/8-16 UNC thread and a knurled head designed for tool-free hand tightening in fixturing, clamping, and machine setup applications. The screw features a black oxide finish for mild corrosion resistance and a swivel pad tip that pivots up to 20 degrees to conform to angled or uneven workpiece surfaces without marring them. Overall length is 3-7/16 inches, with a head diameter of 1-1/4 inches and a head height of 7/16 inches. It ships without a shoulder, making it suitable for direct thread engagement into tapped holes. This part is typically installed by machinists, toolmakers, and mechanical assemblers.

This thumb screw is used in manual clamping fixtures, jigs, dies, and machine tool setups where repeated hand adjustment is required. The swivel pad tip is particularly useful in applications where the clamping surface is not perpendicular to the screw axis, distributing load evenly and protecting finished surfaces. It is suited to light-to-medium duty workholding in both production and maintenance environments.

Key Features

• 3/8-16 UNC thread for broad compatibility with standard tapped fixtures
• Knurled head allows secure hand tightening without tools
• Swivel pad tip pivots up to 20 degrees to seat on non-perpendicular surfaces
• Black oxide finish provides mild corrosion resistance
• No-shoulder design for direct engagement into tapped holes
• Steel construction throughout, including the swivel tip

Compatibility

Designed as a standard replacement or upgrade thumb screw for fixtures, jigs, and manual clamping assemblies using 3/8-16 UNC tapped holes.

Installation Notes

Thread engagement should be confirmed against the depth of the tapped hole before applying clamping load. Hand-tighten only — do not use a wrench or driver on the knurled head, as this can strip the thread or damage the head profile. Inspect the swivel pad tip for free rotation before installation to ensure proper surface contact. No special tools or codes are required for installation of this fastener type.