Accupro T4677405 Spiral Flute Tap 1/4-20 3 Flute

Product Description

The ACCUPRO T4677405 is a spiral flute tap designed for cutting 1/4-20 internal threads in through-hole and modified bottoming applications. Built from 3% Vanadium High Speed Steel with a nitride finish, this tap delivers improved wear resistance and heat tolerance compared to standard HSS taps. It features a 3-flute, slow-helix spiral flute design at a 15-degree helix angle that efficiently evacuates chips upward out of the hole. The 2B class of fit produces standard tolerance threads suitable for the majority of general-purpose fastener assemblies. Machinists, toolroom technicians, and CNC operators use this tap in production and maintenance threading operations.

This tap is suited for threading cast iron workpieces, as specified by its material application rating. The modified bottoming chamfer allows threading closer to the bottom of a blind hole than a standard plug chamfer while still providing some lead-in guidance. Right-hand flute and right-hand thread geometry are standard for conventional clockwise threading operations. With an overall length of 2.5 inches and a shank diameter of 6.48 millimeters, the T4677405 fits standard tap holders and collets sized for this shank diameter.

Key Features

• 1/4-20 thread size with 2B class of fit for standard tolerance general-purpose threads
• 3% Vanadium High Speed Steel construction for improved wear resistance over standard M2 HSS
• Nitride finish reduces friction and extends tool life in ferrous materials
• 15-degree slow spiral helix evacuates chips upward, reducing clogging in blind holes
• Modified bottoming chamfer threads closer to the bottom of a blind hole than a plug tap
• Right-hand flute and right-hand thread for conventional clockwise cutting

Compatibility

Designed for threading cast iron workpieces at 1/4-20 in standard tap holders and collets accepting a 6.48 millimeter shank diameter. Thread limit H5 is appropriate for standard 2B fit threaded assemblies.

Installation Notes

This tap should be installed by a qualified machinist or toolroom technician in a properly aligned tap holder or tapping head. Always ensure the workpiece is securely fixtured and the spindle is centered before beginning the threading operation. Use an appropriate cutting fluid for cast iron to promote chip evacuation and extend tool life. Inspect the tap for wear or chipping before each use and replace if cutting edges are damaged.