Accupro T1620403 Spiral Point Tap 1/4-20 3 Flute

Product Description

The ACCUPRO T1620403 is a spiral point plug tap designed for cutting right-hand internal threads in through-hole applications. Built from vanadium high-speed steel with an oxide finish, it holds an H3 thread limit and a 3B class of fit, making it well suited for work in stainless steel and other demanding materials. The tap measures 2.5 inches overall length with a 19 mm thread length and a shank diameter of 6.48 mm. Machinists and tool and die tradespeople rely on this geometry for production tapping where chip pushing ahead of the cut keeps flutes clear in through-hole work.

This tap is a standard trade-shop tool for threading 1/4-20 holes in ferrous and non-ferrous metals, with particular suitability for stainless steel as noted in the manufacturer application data. The spiral point geometry drives chips forward, reducing clogging in through-hole setups on mills, drill presses, and tapping machines. Its 3-flute, plug chamfer configuration provides a good balance of strength and cutting efficiency across both manual and machine tapping operations.

Key Features

• 1/4-20 thread size with 3B class of fit for standard tolerance through-hole applications
• Vanadium high-speed steel construction for toughness and wear resistance in stainless steel
• Oxide coating reduces friction and provides light corrosion protection during storage and use
• H3 thread limit ensures consistent fit across production runs
• Plug chamfer (3-5 thread lead) for use in through-hole tapping where chip clearance is needed
• Right-hand cut, 3-flute spiral point design compatible with standard tapping machines and hand tapping

Compatibility

Designed as a standard 1/4-20 spiral point plug tap for use in through-hole tapping applications across general machining, maintenance, and fabrication work.

Installation Notes

This tap is installed by qualified machinists or maintenance technicians using a tap wrench, tapping head, or CNC tapping cycle. Ensure the workpiece is securely fixtured and the hole is drilled to the correct tap drill size before threading. Use appropriate cutting fluid for the workpiece material, especially when tapping stainless steel, to reduce heat buildup and extend tool life. Do not force the tap if resistance increases unexpectedly, as breakage can result and may require EDM extraction.