Hertel K008040AS 2-56 Unc Bottoming Tap 3 Flute Hss

Product Description

The HERTEL K008040AS is a straight flute tap designed to cut 2-56 UNC internal threads in a bottoming configuration. Built from high-speed steel with a bright, uncoated finish, this tap is suited for threading close to the bottom of blind holes where full thread engagement is required near the hole floor. It features three flutes and carries a 2B class of fit, producing threads within standard commercial tolerance for general-purpose fastener applications. Overall length is 1.75 inches. The H2 thread limit designation indicates a controlled tap oversize, helping achieve consistent 2B fit across production runs. Machinists and tool-and-die professionals are the primary users.

This tap is applied in machine shop and production environments where small-diameter UNC threads must be cut to the bottom of blind holes. The 2-56 thread size is common in instrument assembly, electronics enclosures, optical equipment, and precision mechanical subassemblies. The bottoming chamfer - typically 1 to 2 threads of lead - requires a starter or plug tap to have already roughed the hole before this tap finishes the thread to depth. Right-hand thread direction is standard for conventional drive setups.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• High-speed steel construction for general-purpose tapping in steel, aluminum, and similar materials
• 2B class of fit with H2 thread limit for controlled, repeatable tolerance
• Three straight flutes for chip clearance in through and shallow blind hole applications
• Bright, uncoated finish - suitable for use with cutting oil or tapping fluid
• Right-hand thread, 2-56 UNC - matches standard inch-series fastener specifications

Compatibility

Designed as a standard replacement or production tap for 2-56 UNC bottoming thread applications in manual or CNC tapping operations using a compatible tap holder or tapping head sized for the shank.

Installation Notes

A licensed machinist or experienced toolroom operator should perform thread tapping operations following applicable shop safety procedures. Ensure the workpiece is securely fixtured and the spindle or tap wrench is properly aligned with the drilled pilot hole before engaging the tap. Always use an appropriate cutting fluid to extend tool life and improve thread quality. Back the tap out periodically to clear chips, and never force a bottoming tap into an unprepared hole - use a taper or plug tap first to rough the thread.