Accupro T2634423 Spiral Flute Tap 1/4-28 3 Flutes

Product Description

The ACCUPRO T2634423 is a spiral flute tap designed for cutting 1/4-28 UNF internal threads in steel workpieces. It features a modified bottoming chamfer, which allows threading closer to the bottom of a blind hole than a standard plug or taper tap. The three right-hand spiral flutes with a 33-degree helix angle evacuate chips upward and out of the hole, reducing clogging during the cut. Built from 3% vanadium high-speed steel with a bright, uncoated finish, this tap is suited for general-purpose threading in a machine or hand-tapping setup. Machinists, tool-and-die workers, and maintenance technicians are the primary users.

This tap is intended for threading steel and similar ferrous materials in production and maintenance environments. The 3B class of fit produces a standard tolerance thread suitable for most general assembly applications requiring 1/4-28 UNF fastener engagement. The H3 thread limit designates the tolerance range for the finished thread, making it appropriate for standard commercial thread fits. It is well suited for blind-hole applications where depth control is important and chip evacuation from a straight-flute tap would otherwise be a concern.

Key Features

• Modified bottoming chamfer for threading near the bottom of blind holes
• 33-degree helix angle spiral flutes evacuate chips upward and out of the hole
• 3% vanadium high-speed steel construction for hardness and wear resistance in steel applications
• H3 thread limit for consistent 3B class of fit tolerance
• Right-hand thread direction, right-hand flute direction
• Bright uncoated finish — no additional coating buildup affecting thread tolerance

Compatibility

Designed for cutting 1/4-28 UNF right-hand internal threads in steel materials; compatible with standard tap holders and collet chucks accepting a 6.48 mm shank diameter.

Installation Notes

This tap should be installed in a properly sized tap holder or collet chuck rated for the shank diameter before use. Secure the workpiece firmly and apply appropriate cutting fluid for steel to extend tool life and improve thread quality. Always back the tap out periodically when hand-tapping blind holes to clear chips and prevent breakage. Inspect the tap for wear or chipping before each use, as a damaged tap can produce out-of-tolerance threads.