Hertel K008425AS Spiral Flute Tap 5/16-24 Unf Bottoming Hss

Product Description

The HERTEL K008425AS is a spiral flute bottoming tap designed to cut 5/16-24 UNF internal threads in through and blind hole applications. Built from high speed steel (HSS) with a bright uncoated finish, it features a 3-flute fast helix design at 52 degrees that evacuates chips upward through the flute, making it well suited for threading soft and medium-hardness materials. The bottoming chamfer allows threading to the bottom of a blind hole with minimal unthreaded length remaining. This tap is ground to an H3 thread limit with a 3B class of fit, providing the tolerance control that precision assemblies require. Licensed machinists, toolroom technicians, and maintenance mechanics are the typical users.

This tap is used in production and maintenance machining environments where 5/16-24 UNF threads are required in blind holes. The fast 52-degree helix angle improves chip flow in materials such as aluminum, mild steel, and plastics. The bottoming chamfer configuration is chosen when thread depth must extend close to the bottom of the hole. It is commonly found in toolrooms, job shops, and field maintenance operations where fine-thread bottoming work demands consistent tolerance performance across repeated cuts.

Key Features

• 5/16-24 UNF thread form, right hand thread and right hand flute
• Bottoming chamfer for threading to the bottom of blind holes
• 52-degree fast helix angle promotes efficient chip evacuation
• H3 thread limit ground to 3B class of fit for precise tolerance control
• High speed steel construction for durability across a range of workpiece materials
• Bright uncoated finish suitable for use with cutting fluids on most common materials

Compatibility

Designed as a standard replacement or addition for toolrooms and machining setups requiring a 5/16-24 UNF bottoming spiral flute tap with an H3 thread limit and 3B class of fit. No coolant-through feature; standard external cutting fluid application applies.

Installation Notes

This tap is installed in a tapping chuck, tap wrench, or CNC tapping head by a machinist or toolroom technician. Always pre-drill with the correct tap drill size for 5/16-24 UNF before tapping. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread quality. Ensure the tap is aligned perpendicular to the workpiece surface before engaging to avoid tap breakage or thread distortion.