Hertel K008303AS Spiral Flute Tap 12-28 Unf Bottoming Hss

Product Description

The HERTEL K008303AS is a spiral flute bottoming tap designed for cutting 12-28 UNF internal threads in machined components. Built from high-speed steel with a bright, uncoated finish, it delivers consistent thread formation in materials suitable for HSS tooling. The 52-degree helix angle and fast flute style evacuate chips upward, making this tap well-suited for blind-hole applications where chip packing is a concern. With an overall length of 2.375 inches and a shank diameter of 0.2200 inches, it fits standard tap holders used in manual and CNC tapping operations. The H3 thread limit holds tight tolerances for 2B and 3B class-of-fit threads.

This tap is used in production and maintenance machining environments where fine unified thread forms are required. The bottoming chamfer allows threading to the bottom of a blind hole, a common requirement in fixture plates, hydraulic manifolds, precision assemblies, and mechanical components across manufacturing and industrial maintenance applications. It is installed by machinists using standard tapping chucks, T-handle tap wrenches, or CNC rigid tapping setups. Right-hand thread direction is standard for the vast majority of UNF fastener applications.

Key Features

• Bottoming chamfer enables threading to the full depth of blind holes
• 52-degree helix angle with fast flute style for efficient upward chip evacuation
• High-speed steel construction provides durability across a range of work materials
• H3 thread limit holds 2B and 3B class-of-fit tolerances
• Right-hand, 3-flute design balances cutting forces and tool rigidity at this thread size
• Bright, uncoated finish — no coating thickness to account for in tolerance-critical applications

Compatibility

Designed as a standard replacement or production tap for 12-28 UNF bottoming applications in machining operations using HSS-compatible tapping equipment.

Installation Notes

This tap is installed by machinists and toolroom technicians using a properly sized tap wrench or tapping chuck rated for the shank diameter. Ensure the workpiece is securely fixtured and that the tap is started perpendicular to the hole to prevent thread misalignment. Use appropriate cutting fluid for the work material to extend tool life and produce cleaner thread forms. Follow shop-standard speeds and feeds for HSS tapping at this thread size to avoid tap breakage in blind holes.