Hertel K008328AS Straight Flute Tap 1/4-20 Unc Hss

Product Description

The HERTEL K008328AS is a straight flute tap designed for cutting internal threads in ferrous and non-ferrous materials. Built from high-speed steel (HSS) with a bright/uncoated finish, this tap cuts a 1/4-20 UNC right-hand thread to a 2B class of fit with an H5 thread limit. It features three straight flutes and a plug chamfer, making it well-suited for through-hole applications where chips can flow ahead of the tap. Overall length is 2.5 inches and the tap weighs approximately 0.35 pounds. It is a standard production-grade tool used in machine shop, maintenance, and field service environments.

This tap is used in through-hole tapping operations on 1/4-20 UNC fastener applications. The plug chamfer — typically 3 to 5 threads of lead — is the standard choice for production tapping in through holes, providing a gradual thread engagement. The 2B class of fit is the most common tolerance class for general-purpose unified inch threads, compatible with standard 2A externally threaded fasteners. Typical applications include tapping steel, cast iron, aluminum, and similar materials in industrial and mechanical assembly work.

Key Features

• 1/4-20 UNC thread form with right-hand thread direction
• Plug chamfer for through-hole tapping with gradual thread lead-in
• H5 thread limit for precise tolerance control within 2B class of fit
• Three straight flutes for chip clearance in through-hole applications
• High-speed steel construction for durability across a range of workpiece materials
• Bright/uncoated finish — no added coating that could affect thread tolerance

Compatibility

Designed as a standard replacement or production-grade tap for through-hole applications requiring a 1/4-20 UNC thread to a 2B class of fit. Compatible with standard tap holders and machine tapping chucks sized for 1/4-inch shank taps.

Installation Notes

This tap is installed and operated by machinists and maintenance technicians using a tap wrench, tapping head, or CNC machine tool holder. Always use appropriate cutting fluid for the workpiece material to extend tool life and improve thread quality. Ensure the tap is aligned perpendicular to the workpiece before engagement. Do not force a tap that has become stuck — back off and clear chips before continuing.