Irwin 6540 Hex Rethreading Die 7/16-20 1 Inch Hex

Product Description

The IRWIN 6540 is a hex rethreading die designed to restore damaged or corroded external threads without removing the fastener or fitting from service. The die cuts a 7/16-20 UNF thread profile in the right-hand direction and seats in a standard 1-inch hex holder or tap wrench for controlled torque application. Built from carbon steel, it delivers the hardness needed to chase threads on steel fasteners, bolts, and fittings commonly found in mechanical, plumbing, and HVAC assemblies. Weighing 0.5 pounds, the 6540 is a compact, single-piece tool suited for field service kits and shop toolboxes alike.

This rethreading die is used wherever a 7/16-20 UNF external thread needs to be cleaned up or restored — including hydraulic fittings, threaded fasteners, and machine bolts found in residential and light commercial mechanical systems. It is a practical addition to any service technician's thread restoration set when dealing with corroded or impact-damaged threads that do not require full thread cutting from blank stock.

Key Features

• 7/16-20 UNF thread profile restores fine-pitch external threads
• Right-hand thread direction for standard fastener applications
• 1-inch hex body fits standard hex holders and adjustable tap wrenches
• Carbon steel construction provides hardness for thread chasing on steel fasteners
• Compact single-piece design suits field service and shop use

Compatibility

Designed as an OEM-style rethreading die for use on 7/16-20 UNF right-hand external threads on bolts, studs, and fittings requiring thread restoration.

Installation Notes

Thread rethreading dies are typically used by machinists, pipefitters, HVAC technicians, and plumbers performing field repairs. Always de-energize, depressurize, and isolate the assembly before working on threaded connections. Apply cutting oil or thread lubricant to the die before use to reduce heat buildup and improve thread quality. Do not force the die past resistance — back off periodically to clear chips.