Hertel K007005AS Spiral Point Sti Tap 4-40 Unc 2 Flutes

Product Description

The HERTEL K007005AS is a spiral point STI tap designed to cut 4-40 UNC threads in pre-drilled holes intended for HeliCoil-style thread inserts. Manufactured from high-speed steel with a bright uncoated finish, this tap features a plug chamfer and two flutes. The spiral point geometry pushes chips forward ahead of the cutting action, making it well-suited for through-hole tapping operations. It measures 2 inches in overall length and carries an H2 thread limit, which specifies the tolerance class of the finished thread. Machinists, maintenance technicians, and tool-and-die tradespeople use this tap when restoring or reinforcing stripped or damaged threads in metal components.

This tap is used in applications where a standard thread has been damaged or where additional thread strength is required in softer base materials such as aluminum or cast iron. The STI thread form is oversized relative to standard UNC, creating the correct minor and major diameters needed to accept a HeliCoil or equivalent wire thread insert after tapping. It is appropriate for both production and repair work in light manufacturing, aerospace maintenance, and general machine shop environments. The Helicoil reference number for this tap is 04CSA.

Key Features

• STI UNC thread form sized for HeliCoil-style wire thread insert installation
• Spiral point geometry pushes chips forward, suited for through-hole tapping
• H2 thread limit provides controlled tolerance for consistent thread fit
• High-speed steel construction handles a range of ferrous and non-ferrous materials
• Bright uncoated finish allows visual wear monitoring during use
• 2-inch overall length fits standard tap handles and machine tool holders

Compatibility

Designed as an OEM-style STI tap for use with HeliCoil and equivalent wire thread insert systems in 4-40 UNC applications. Helicoil reference number 04CSA.

Installation Notes

This tap should be installed and operated by a qualified machinist or maintenance technician familiar with thread insert repair procedures. Always secure the workpiece and use appropriate cutting fluid for the base material being tapped. Ensure the pilot hole is drilled to the correct STI tap drill diameter before tapping, as this differs from standard UNC tap drill sizes. Follow the thread insert manufacturer's instructions for insert installation after tapping is complete.