Electro Hardware THS1139M10F21 Steel Thumb Screw 1/4-20

Product Description

The ELECTRO HARDWARE THS1139M10F21 is a steel thumb screw with a knurled head, designed for tool-free fastening in light assembly and panel applications. It features a 1/4-20 UNC thread and a brass knurled head measuring 0.5 inches in diameter and 0.25 inches in height. The with-shoulder design includes a shoulder diameter of 0.437 inches and a shoulder length of 0.125 inches, providing a positive stop against mating surfaces. The overall length is 1 inch. A zinc finish on the steel body provides corrosion resistance. Installers in HVAC, electrical, and light industrial assembly use this fastener where hand-tightening is required and tools are not practical.

This thumb screw is suited for panel covers, access doors, junction boxes, and equipment enclosures across residential and commercial applications. The knurled brass head allows for secure hand tightening without tooling, making it a common choice for frequently removed covers and serviceable assemblies. It is sold in packages of 1, with a minimum order quantity of 2.

Key Features

• 1/4-20 UNC thread for broad compatibility with standard tapped panels and enclosures
• Knurled brass head for tool-free installation and removal
• With-shoulder design provides a positive stop at 0.437 inch shoulder diameter and 0.125 inch shoulder length
• Zinc-finished steel body for corrosion resistance in light-duty environments
• Compact 1 inch overall length suits shallow panel and enclosure applications
• Meets multiple military and ASTM standards including ASTM B633

Compatibility

Designed as a standard 1/4-20 UNC thumb screw for use in panels, enclosures, and equipment covers that accept a 1/4-20 tapped hole.

Installation Notes

Installation requires no special tools due to the knurled head design. Power down or de-energize any equipment before removing or replacing panel fasteners. Verify the mating thread is clean and free of debris before installation to avoid cross-threading. Apply hand pressure only when tightening to avoid stripping the brass head or the mating thread.