Accupro T1620422B Spiral Point Tap 1/4-28 Vanadium Hss

Product Description

The ACCUPRO T1620422B is a spiral point tap designed for threading 1/4-28 UNF holes in demanding materials, including stainless steel. Built from 3% vanadium high-speed steel (HSS-E), it delivers increased wear resistance and edge retention compared to standard HSS taps. The plug chamfer allows progressive thread engagement over several leading threads, making it well suited for through-hole tapping applications. With 3 flutes and a right-hand thread direction, the spiral point geometry pushes chips forward ahead of the cutting zone, reducing chip congestion in the flute. The oxide finish provides a base level of lubricity and corrosion resistance during storage and use. Overall length is 2.5 inches with a thread length of 19 millimeters.

This tap is used in machine shop, maintenance, and field repair applications where 1/4-28 UNF threads are required in through-hole configurations. It is particularly suited for stainless steel and other difficult-to-machine materials where a vanadium-grade HSS tool provides improved tool life over standard M2 HSS. Typical users include machinists, tool and die technicians, industrial maintenance mechanics, and fabricators working with threaded fastener repairs or original equipment production. The 2B class of fit produces standard commercial-grade internal threads compatible with 2A class fasteners.

Key Features

• 1/4-28 UNF thread size with 2B class of fit for standard commercial thread tolerances
• 3% vanadium HSS-E construction for improved wear resistance in stainless steel and alloy materials
• Spiral point geometry pushes chips forward, reducing packing in through-hole applications
• Plug chamfer with 3 flutes for progressive thread engagement and balanced cutting action
• Oxide finish provides surface lubricity and corrosion protection
• Right-hand thread direction, no coolant-through requirement

Compatibility

Designed for cutting 1/4-28 UNF right-hand internal threads in through-hole applications, with a stated material application of stainless steel. Compatible with standard tap holders and chucks accepting a 6.48 millimeter shank diameter.

Installation Notes

This tap is installed by machinists and maintenance technicians using a tap wrench, tapping head, or CNC rigid tapping setup. Before tapping, verify the correct drill size for a 1/4-28 UNF thread and ensure the workpiece is securely clamped. Use appropriate cutting fluid for the workpiece material, particularly when threading stainless steel, to reduce heat buildup and extend tool life. Do not reverse the tap under power without confirming the machine is set up for rigid tapping to avoid tap breakage.