Jergens 43904 Thumb Screw 1/4-20 Knurled Head Dog Point

Product Description

The JERGENS 43904 is a 1215 steel thumb screw with a knurled head and dog point tip, designed for tool-free manual adjustment and positive positioning in jigs, fixtures, and tooling applications. Finished in black oxide for corrosion resistance, it carries a 1/4-20 UNC thread and measures 1-13/16 inches in overall length. The knurled head provides a secure grip for hand-tightening without tools, while the dog point tip seats reliably into mating locating holes for repeatable positioning. This is a standard industrial fastener installed by machinists, toolmakers, maintenance technicians, and mechanical assemblers working with fixtures and mechanical assemblies.

This thumb screw is suited for use in precision tooling, workholding fixtures, machine guards, access panels, and general mechanical assemblies that require frequent manual adjustment or removal without tools. The dog point tip is specifically selected for applications requiring indexed or located positioning, where the tip engages a drilled or bored recess in the mating component. The 1/4-20 UNC thread is one of the most common thread sizes in inch-measurement tooling and is widely used across industrial and light mechanical applications.

Key Features

• 1/4-20 UNC thread for broad compatibility with standard inch-measurement tooling and fixtures
• Knurled head design enables tool-free hand-tightening and rapid adjustment
• Dog point tip for positive seating in locating holes and indexed positioning
• Black oxide finish provides mild corrosion resistance and a clean appearance
• 1215 steel construction delivers reliable strength for standard clamping and adjustment loads
• No-shoulder configuration for straightforward through-hole or threaded insert installation

Compatibility

Designed as a standard replacement or new-installation thumb screw for jigs, fixtures, and mechanical assemblies using 1/4-20 UNC threaded holes requiring a knurled head with dog point tip.

Installation Notes

Installation requires no special tools beyond hand pressure for thread engagement. Ensure the mating threaded hole or insert is clean and free of debris before installation. Do not exceed hand-tightening torque for this style of fastener, as over-torquing a knurled thumb screw can damage threads in softer mating materials. Verify the dog point tip aligns with the locating recess in the mating part before applying clamping force.