E-z Lok 335-4 Thread Locking Insert 1/4-20 Unc Carbon Steel

Product Description

The E-Z LOK 335-4 is a self-locking threaded insert designed to create a secure, vibration-resistant internal thread in drilled or tapped holes. It features a 1/4-20 internal thread and a 1/2-13 external thread, both cut to UNC standard. The insert is machined from C12L14 carbon steel with a smooth, rolled finish, delivering a tensile strength of 5,285 pounds. At 31/64 inches overall length, it installs into standard tapped holes using a conventional tap. Licensed HVAC techs, millwrights, maintenance mechanics, and plumbers use this type of insert to repair stripped threads or to anchor fasteners in softer base materials.

This insert is suited for light industrial, mechanical, and trade service applications where a permanent, load-bearing internal thread is needed. The self-lock wall design creates interference between the insert and the parent material, eliminating thread movement under dynamic or vibrational loads. Typical installations include sheet metal frames, cast housings, equipment panels, and structural assemblies where standard tapped holes are insufficient or have been damaged. A standard 1/2-13 tap prepares the host material for installation.

Key Features

• 1/4-20 internal thread and 1/2-13 external thread, both UNC standard
• Self-lock wall design resists loosening under vibration and dynamic load
• C12L14 carbon steel construction with 5,285-pound tensile strength
• 31/64 inches overall length for compact, low-profile installation
• Internal thread class of fit 2B, external thread class of fit 2A
• Installs with a standard tap - no special tooling required

Compatibility

Designed as an OEM-style replacement or new-installation thread repair insert for applications requiring a 1/4-20 internal UNC thread in a 1/2-13 tapped hole across a wide range of mechanical and trade assemblies.

Installation Notes

Installation is performed by mechanics, millwrights, or licensed tradespeople with threaded fastener repair experience. The host material must be tapped to 1/2-13 UNC using a standard tap before the insert is driven in. Power down or de-energize any equipment before beginning thread repair work on live assemblies. Do not exceed the rated tensile load of 5,285 pounds when specifying fasteners for this insert.