Accupro T2644425 Spiral Flute Tap 1/4-28 2 Flute Hss

Product Description

The ACCUPRO T2644425 is a spiral flute tap designed for cutting 1/4-28 unified fine threads in a wide range of materials. Built from 3% Vanadium High Speed Steel with a bright/uncoated finish, it delivers consistent chip evacuation in blind-hole applications. The fast helix angle of 40 degrees drives chips up and out of the hole during threading, reducing the risk of chip packing. With a modified bottoming chamfer and an H5 thread limit, this tap is suited for applications requiring threads close to the bottom of a blind hole with controlled tolerance. Machinists and toolroom technicians are the primary users of this tap.

This tap is used in machining operations where 1/4-28 UNF internal threads are required in blind holes. The modified bottoming chamfer allows threading closer to the hole bottom compared to a plug or taper chamfer. With a 40-degree right-hand spiral flute and right-hand thread direction, it is well suited for CNC machining centers and manual tapping operations on ferrous and non-ferrous workpiece materials. It is sold individually and appropriate for production or toolroom use.

Key Features

• 1/4-28 UNF thread size for unified fine thread applications
• Modified bottoming chamfer for threading near the bottom of blind holes
• 40-degree fast helix spiral flute promotes upward chip evacuation
• 3% Vanadium High Speed Steel construction for extended tool life
• H5 thread limit for controlled tolerance threading
• Bright/uncoated finish compatible with a wide range of cutting fluids and materials

Compatibility

Designed as a direct-fit spiral flute tap for standard 1/4-28 UNF blind-hole tapping operations on CNC and manual machines accepting a 6.48 mm shank diameter.

Installation Notes

This tap is installed and operated by machinists or toolroom technicians using a tap holder, tapping head, or rigid CNC toolholder. Always ensure the workpiece is securely fixtured and the spindle speed is appropriate for the workpiece material before beginning the tapping cycle. Apply a suitable cutting fluid or tapping compound to extend tool life and improve thread finish. Inspect the tap for wear or chipping before each use and replace if the chamfer or flutes show damage.