Accupro T4677162 Spiral Flute Tap 4-40 2 Flute Nitride

Product Description

The ACCUPRO T4677162 is a spiral flute tap designed for cutting 4-40 unified inch threads in through-hole and modified bottoming applications. Manufactured from 3 percent vanadium high speed steel (HSS), it delivers increased wear resistance and edge retention compared to standard M2 HSS. The nitride finish reduces friction and resists galling during the tapping cycle. With a 2-flute, right-hand spiral flute configuration and a 15-degree helix angle, this tap efficiently evacuates chips out of the hole, making it well suited for blind-hole work in ferrous materials. Overall length is 1.87 inches.

This tap is rated for Class of Fit 2B and 3B, covering the full range of standard and close-tolerance 4-40 threaded assemblies. It carries a Thread Limit of H2, which accommodates most standard 4-40 tapping applications in cast iron and similar ferrous workpiece materials. Typical applications include tapping small fastener holes in machined components, fixtures, and enclosures where a compact, accurate thread form is required. The modified bottoming chamfer allows threading closer to the bottom of blind holes than a plug-style tap while still providing adequate lead-in for alignment.

Key Features

• 4-40 unified inch thread size, right-hand thread direction
• 3 percent vanadium HSS construction for extended tool life in cast iron and ferrous materials
• Nitride finish reduces friction and improves chip flow
• 2-flute right-hand spiral flute with 15-degree helix angle for efficient chip evacuation in blind holes
• Modified bottoming chamfer for threading close to the bottom of blind holes
• H2 thread limit, Class of Fit 2B and 3B

Compatibility

Designed for use in cast iron and general ferrous workpiece materials requiring a 4-40 unified inch internal thread. Suitable for CNC tapping centers, drill presses, and hand-tapping applications where a 2B or 3B class of fit is specified.

Installation Notes

This tap is installed by machining professionals and toolroom technicians using standard tapping equipment or tap handles. Ensure the workpiece is securely clamped and the tap is properly aligned to the drilled hole before starting the thread. Use a cutting fluid or tapping compound appropriate for the workpiece material to extend tool life and improve thread finish. Inspect the tap for wear or chipping before each use and replace if cutting edges show damage.