Hertel G837580 Extension Tap 1/4-20 Hss Plug 4 Flutes

Product Description

The HERTEL G837580 is a high speed steel extension tap designed for cutting 1/4-20 UNC internal threads in applications that require reach beyond a standard-length tap. With a 4-inch overall length and a reduced shank diameter of 0.185 inches, this tap accesses recessed or deep holes where standard taps cannot reach. The plug chamfer provides gradual thread engagement, making it well suited for through-hole tapping. Four flutes provide adequate chip clearance in most ferrous and non-ferrous materials. The H3 thread limit and 3B class of fit deliver a medium-fit tolerance appropriate for general mechanical assemblies. The bright, uncoated finish allows easy visual inspection of the cutting edges.

This tap is used in machining and fabrication shops for hand tapping or machine tapping operations where extended reach is required. Typical applications include threading blind or deep through-holes in machine components, fixtures, and structural assemblies made from steel, cast iron, aluminum, or similar materials. The 1/4-20 UNC thread form is one of the most common fastener standards in North American mechanical work, making this tap a practical addition to any toolroom or field maintenance kit. It is sold individually and is appropriate for use by machinists, maintenance technicians, and tool-and-die professionals.

Key Features

• 1/4-20 UNC thread form with H3 thread limit for consistent 3B class of fit tolerance
• 4-inch overall length with reduced shank for extended reach into deep or recessed holes
• Plug chamfer with 4 flutes for smooth thread lead-in in through-hole applications
• High speed steel construction provides good wear resistance across a range of workpiece materials
• Bright, uncoated finish simplifies edge inspection and suits general-purpose tapping without coolant buildup concerns

Compatibility

Designed as a general-purpose extension tap for 1/4-20 UNC through-hole threading operations in standard machine tapping and hand tapping setups.

Installation Notes

This tap is installed by machinists or maintenance technicians using a tap handle, tapping arm, or CNC machine with appropriate feed control. Always secure the workpiece before tapping and apply cutting fluid compatible with the workpiece material to reduce friction and extend tool life. Inspect the tap for chipping or wear before each use, as a damaged tap can seize in the hole and require extraction. Do not force the tap past its cutting capacity, as high speed steel tools are brittle under side loading.