Hertel K008370AS Spiral Flute Tap 1/4-28 Unf Plug Hss

Product Description

The HERTEL K008370AS is a spiral flute tap designed for cutting internal threads in ferrous and non-ferrous materials where chip evacuation is critical. Built from high-speed steel, this tap features a right-hand spiral flute configuration with a 52-degree helix angle that pulls chips up and out of the hole during the tapping operation. The plug chamfer provides a gradual lead-in with roughly 3 to 5 threads of taper, making it well suited for through-holes. Overall length is 2.5 inches, and the tap is ground to an H3 thread limit with a 3B class of fit for standard tolerance threading applications.

This tap is intended for machinists, maintenance technicians, and tool-and-die professionals working with 1/4-28 UNF fine-thread fastener requirements. The fast flute style and 52-degree helix angle make it particularly effective in blind-hole applications where conventional straight-flute taps struggle to clear chips. Typical applications include threading tapped holes in steel, aluminum, and cast iron components on manual lathes, drill presses, and CNC machining centers. It is sold individually.

Key Features

• 1/4-28 UNF right-hand thread, ground to H3 thread limit and 3B class of fit
• 52-degree helix angle with fast flute style for efficient upward chip evacuation
• Plug chamfer provides gradual lead-in suitable for through-hole applications
• High-speed steel construction for general-purpose threading in a range of workpiece materials
• 2.5-inch overall length compatible with standard tap holders and tapping heads
• No coolant-through feature; apply cutting fluid externally as required

Compatibility

Designed as a standard-shank spiral flute tap for use with 1/4-28 UNF threading applications; fits conventional tap holders and collet chucks sized for 1/4-inch taps. No specific machine or system compatibility was provided in the product data.

Installation Notes

Installation should be performed by a qualified machinist or maintenance technician familiar with threading operations. Ensure the workpiece is securely fixtured and the spindle or tapping head is properly aligned before engagement. Apply an appropriate cutting fluid or tapping compound to extend tool life and improve thread finish. Inspect the tap for wear or chipping before each use and replace if flute edges show damage.