Hertel K007050AS Spiral Point Sti Tap 1/4-20 Unc

Product Description

The HERTEL K007050AS is a spiral point STI tap designed for cutting Screw Thread Insert (STI) threads in a 1/4-20 UNC configuration. It is manufactured from high-speed steel with a bright, uncoated finish. The plug chamfer style makes it suitable for through-hole tapping applications where the tool can advance freely through the material. With an overall length of 2-23/32 inches and a thread length of 1-1/8 inches, this tap handles typical fastener-depth requirements in metal fabrication, maintenance, and repair work. The H2 thread limit specifies the tolerance class of the cut thread. Machinists and maintenance technicians use this tap when installing Helicoil-style thread inserts to restore or reinforce stripped or damaged threads.

This tap is used in applications requiring STI UNC thread form, specifically to prepare holes for 1/4-20 thread repair inserts. Common scenarios include restoring worn threads in aluminum, cast iron, and steel components across industrial, mechanical, and field-repair settings. The 2-flute design provides chip clearance and allows the spiral point to push chips ahead of the cut, making it well suited for use in CNC machines, drill presses, or hand tapping operations on through-holes.

Key Features

• STI UNC thread form for use with 1/4-20 Helicoil-style thread inserts (Helicoil Reference Number: 4CSB)
• High-speed steel construction provides durability across a range of ferrous and non-ferrous workpiece materials
• Bright, uncoated finish suitable for general-purpose tapping applications
• Plug chamfer allows continuous chip advancement in through-hole tapping
• H2 thread limit ensures consistent thread tolerance for reliable insert fitment
• 2-flute spiral point geometry promotes efficient chip evacuation during the cut

Compatibility

Designed for use in 1/4-20 UNC STI thread repair applications using Helicoil-style inserts; Helicoil Reference Number 4CSB is cited in the product data for insert cross-reference.

Installation Notes

This tap is installed by machinists or maintenance technicians using a standard tap handle, tapping head, or CNC rigid-tapping setup. The workpiece must be secured and the pre-drilled hole must conform to the STI tap drill size specified for 1/4-20 STI threads before use. Always use cutting fluid appropriate for the workpiece material to extend tool life and improve thread quality. Ensure the tap is properly aligned with the hole axis to prevent tap breakage or off-axis threads.