Hertel R867152 Extension Plug Tap 3/8-16 Unc 4 Flute Hss

Product Description

The HERTEL R867152 is a 3/8-16 UNC extension plug tap designed for threading applications that require additional reach beyond a standard-length tap. Built from high speed steel (HSS) with a bright, uncoated finish, this tap features four flutes and an H3 thread limit, making it well suited for cutting threads in through-holes and blind holes where plug chamfer lead-in is appropriate. The overall length of 6 inches gives technicians and machinists access to deeper bores or recessed features that standard taps cannot reach. The reduced shank at 0.275 inches in diameter is designed to fit through the clearance required for extension work.

This tap is used in metal fabrication, maintenance and repair, and general machining environments where 3/8-16 UNC threads are required in hard-to-reach locations. The plug chamfer — typically 3 to 5 threads of taper — provides a balanced lead-in suitable for both through-holes and moderately deep blind holes. The 3B class of fit produces a standard commercial thread tolerance appropriate for most bolted assemblies and fastener applications. Machinists, toolmakers, and MRO technicians working on equipment with deep bosses or extended features will find this extension tap a practical solution.

Key Features

• 3/8-16 UNC thread form with H3 thread limit for consistent fit and tolerance control
• 6-inch overall length provides extended reach for deep or recessed bores
• Plug chamfer lead-in with 4 flutes for chip clearance in a range of materials
• High speed steel construction for durability in general-purpose threading operations
• Bright, uncoated finish — no coating buildup that could affect thread tolerance
• Reduced shank diameter of 0.275 inches enables use in extension tap holders

Compatibility

Designed for use in standard extension tap holders accepting a reduced shank diameter of 0.275 inches. Cuts 3/8-16 UNC threads to a 3B class of fit in ferrous and non-ferrous materials suited to HSS tooling.

Installation Notes

This tap should be installed by a qualified machinist or toolroom technician using a properly sized extension tap holder or tap wrench rated for the shank diameter. Ensure the workpiece is securely fixtured and that the tap is aligned perpendicular to the hole before starting the thread. Use a cutting fluid appropriate for the workpiece material to extend tool life and improve thread finish. Inspect the tap for wear or chipping before each use and do not force a tap that has seized, as HSS taps can fracture under torsional overload.