Hertel K033012AS Spiral Flute Tap 1/4-28 Unf Hss

Product Description

The HERTEL K033012AS is a spiral flute tap designed for cutting internal threads in materials that produce stringy or continuous chips. It uses a right-hand, fast-flute spiral design with a 52-degree helix angle to efficiently evacuate chips up and out of the hole during the tapping operation. The tap is ground to a 1/4-28 UNF thread profile with an H3 thread limit and a 3B class of fit, suitable for standard-tolerance threaded holes. Manufactured from high-speed steel with a bright, uncoated finish, it measures 2.5 inches overall length. Machinists and tool-room technicians use this tap in CNC machining centers, manual mills, and drill presses.

This tap is suited for through-hole and blind-hole applications in ferrous metals, aluminum, and similar materials where chip evacuation is a priority. The plug chamfer style provides 3 to 5 lead threads, making it appropriate for through-hole tapping or as a follow-up pass after a taper tap in blind holes. It is commonly used in production machining, job shop work, and maintenance-repair-operations environments requiring consistent 1/4-28 UNF threads.

Key Features

• 52-degree helix angle promotes efficient chip evacuation in through-hole applications
• H3 thread limit for 3B class of fit — consistent tolerance on internal threads
• High-speed steel construction for durability across a range of common workpiece materials
• Plug chamfer with 3 flutes balances thread-starting ease and cutting load
• Bright, uncoated finish compatible with a wide range of cutting fluids
• Right-hand thread and right-hand flute direction for standard tapping setups

Compatibility

Designed as a standard replacement or production-use spiral flute tap for applications requiring 1/4-28 UNF internal threads with a 3B class of fit and H3 thread limit.

Installation Notes

This tap should be installed in a tapping chuck or collet that provides axial float to prevent thread distortion. Always use an appropriate cutting fluid for the workpiece material and ensure the tap is properly aligned with the pilot hole before engaging. Secure the workpiece firmly before beginning the tapping cycle. Replace the tap at first signs of wear or thread-form degradation to maintain tolerance.