Hertel K007028AS Hand Sti Tap 8-32 Unc H3 Bottoming

Product Description

The HERTEL K007028AS is a hand STI tap designed to cut Screw Thread Insert (STI) threads in metallic workpieces. It produces an oversized internal thread that accepts helical coil inserts, restoring or reinforcing threaded holes to standard fastener dimensions. The tap is ground from High Speed Steel with a Bright finish and features 3 flutes for chip clearance in typical hand-tapping applications. With an 8-32 UNC thread form, an H3 thread limit for controlled tolerance, and a Bottoming chamfer, it is suited for threading to the bottom of blind holes. Machinists, maintenance technicians, and tool-and-die professionals install this tap by hand or with a tap wrench.

This tap applies to applications where a standard 8-32 UNC thread must be reinforced with a helical coil insert — common in aluminum, magnesium, and soft-metal assemblies where thread wear or strip-out has occurred. The Bottoming chamfer engages cut threads within 1-2 thread lengths of the hole bottom, making it appropriate for shallow blind holes. A plug or taper tap is typically used first to start the thread; the K007028AS finishes the thread to full depth. It is also used when creating new STI threads from scratch in materials that benefit from insert reinforcement.

Key Features

• 8-32 UNC thread form produces STI-oversized internal threads for helical coil insert installation
• H3 thread limit provides controlled tolerance for consistent insert fit
• Bottoming chamfer allows threading close to the bottom of blind holes
• 3-flute geometry supports chip evacuation during hand tapping
• High Speed Steel construction provides hardness and wear resistance for ferrous and non-ferrous materials
• Bright finish with no coating for straightforward inspection of tap condition

Compatibility

Designed as an OEM-style hand STI tap for use with standard 8-32 UNC helical coil thread insert systems in general metalworking, maintenance, and repair applications.

Installation Notes

Installation is performed by machinists or maintenance technicians using a tap wrench or T-handle. The workpiece should be secured and the hole drilled to the correct STI tap drill diameter before tapping begins. Use appropriate cutting fluid for the workpiece material to extend tap life and improve thread quality. Do not force the tap — back off periodically to break chips and avoid tap breakage in hard or deep holes.