Hertel K008354AS 1/4-28 Unf Bottoming Tap 4 Flutes Hss

Product Description

The HERTEL K008354AS is a straight flute bottoming tap designed for cutting right-hand internal threads in a 1/4-28 UNF specification. Built from high-speed steel with a bright, uncoated finish, this tap is suited for threading operations that require the thread to run as close to the bottom of a blind hole as possible. It carries a 3B class of fit and an H3 thread limit, providing the tolerance control needed for standard fastener applications. With 4 flutes and an overall length of 2.5 inches, it is a dependable hand or machine tap for precision threading in ferrous and non-ferrous materials across maintenance, toolroom, and production environments.

This tap is used in metalworking applications where a fine-pitch unified thread is required in a blind-hole configuration. The bottoming chamfer style leaves only 1 to 2 threads of lead, allowing the tap to thread nearly to the full depth of the hole. It is appropriate for use in manual tapping, CNC tapping operations, or drill press setups where thread depth control is critical. Machinists, maintenance technicians, and tool-and-die professionals working on mechanical assemblies, fixtures, or repair work will find this tap suited to standard production and repair threading tasks.

Key Features

• 1/4-28 UNF thread form with right-hand thread direction
• Bottoming chamfer allows threading to near-full depth in blind holes
• 4 straight flutes for chip control in through and shallow blind-hole applications
• H3 thread limit for consistent tolerance in 3B class-of-fit applications
• High-speed steel construction provides durability across a range of workpiece materials
• Bright uncoated finish - no coating buildup to alter thread tolerance

Compatibility

Designed as an OEM-style straight flute bottoming tap for use in standard 1/4-28 UNF tapping applications requiring a 3B class of fit. Compatible with tap holders and tapping heads sized for standard 1/4-inch tap shanks.

Installation Notes

Bottoming taps should be used as the final step in a three-tap sequence - after a taper tap and plug tap have already formed the thread - to achieve maximum thread depth in blind holes. Always ensure the hole is drilled to the correct tap drill size and depth before starting the tapping sequence. Power down or de-energize any machine before changing or setting tooling. Use cutting fluid appropriate for the workpiece material to extend tap life and improve thread finish.