Hertel R837679 Extension Tap 7/16-20 Hss Spiral Point

Product Description

The HERTEL R837679 is a spiral point plug extension tap designed for cutting unified fine threads in through-hole applications. It features a 7/16-20 UNF thread form with an H3 thread limit, making it suitable for applications that require controlled fit and precise thread tolerance. The spiral point geometry pushes chips forward ahead of the tap, keeping the flute area clear during cutting. Built from high speed steel with a bright uncoated finish, this tap delivers consistent performance in ferrous and non-ferrous materials. The overall length of 6 inches provides reach in recessed bores and extended-depth applications where standard-length taps cannot access the work zone. It is a go-to tool for machinists, maintenance mechanics, and production shops.

This extension tap is intended for through-hole tapping operations in components where the thread starting point is recessed or offset from the surface. The 3-class B fit (3B) produces a standard commercial thread that mates with 3A external threads across a wide range of fastener and assembly applications. The reduced shank design allows use in standard tap holders and extension adapters. Common installation contexts include machine shops, maintenance and repair operations, and production floor tapping on fixtures, frames, housings, and structural components.

Key Features

• Spiral point geometry pushes chips forward for clean through-hole tapping
• 7/16-20 UNF thread size with H3 thread limit for controlled tolerance fits
• High speed steel construction for use across a broad range of workpiece materials
• 6-inch overall length provides extended reach into recessed or deep bore locations
• Plug chamfer allows easy thread starting and progressive cut engagement
• 3B class of fit produces standard commercial threads compatible with 3A fasteners

Compatibility

Designed as an OEM-style replacement or direct-use extension tap for 7/16-20 UNF through-hole tapping applications. Fits standard tap holders and extension adapters that accept reduced-shank taps.

Installation Notes

Extension taps should be installed in a tap holder or drill press adapter rated for the shank diameter before use. Ensure the workpiece is securely fixtured and the tap is aligned perpendicular to the hole axis to prevent tap breakage. Apply appropriate cutting fluid for the workpiece material to extend tap life and improve thread finish. Machinists and tool and die professionals familiar with tapping operations are the intended users for this tooling.