Hertel R867175 Extension Tap 1-8 Unc H3 4 Flute Hss

Product Description

The HERTEL R867175 is a 1-8 UNC extension tap designed for threading operations that require reach beyond what a standard-length tap can provide. Built from high speed steel with a bright uncoated finish, this plug chamfer tap cuts through ferrous and non-ferrous materials in production and maintenance environments. The H3 thread limit provides a controlled tolerance class suitable for general-purpose UNC threading. With 4 flutes and an 8-inch overall length, it suits deep-hole applications where standard taps fall short. A reduced shank measuring 0.80 inches in diameter accommodates a range of tap holders and extension fixtures. At 1.07 pounds, the tool is substantial enough for rigid machine setups and hand-tapping with a T-handle or tap wrench.

This tap is used in machining, fabrication, and maintenance applications requiring 1-8 UNC internal threads at extended reach. The plug chamfer style — with its moderate lead-in — makes it suitable for through-holes and deeper blind holes where a taper chamfer is not required. It is commonly used in job shops, OEM production lines, and field maintenance settings where large-diameter, coarse-pitch threads must be cut cleanly in steel, cast iron, aluminum, and similar materials. Machinists, millwrights, and maintenance technicians are the typical end users.

Key Features

• 1-8 UNC thread form with H3 thread limit for controlled tolerance fitment
• Plug chamfer provides 3-5 thread lead-in, suitable for through-holes and deeper blind holes
• High speed steel construction provides toughness across a wide range of workpiece materials
• 8-inch overall length extends reach for deep-hole and obstructed-access threading
• Reduced shank diameter of 0.80 inches for compatibility with standard extension holders
• 4-flute design balances chip clearance and cutting edge support in general-purpose applications

Compatibility

Designed for use in standard tap holders and extension fixtures accepting a 0.80-inch reduced shank diameter. Intended for general-purpose 1-8 UNC threading applications in production and maintenance setups.

Installation Notes

Extension taps of this size are typically operated by machinists or millwrights using a rigid tapping setup, CNC machine, or heavy-duty tap wrench. Ensure the workpiece is securely fixtured and properly pilot-drilled to the correct tap drill size for 1-8 UNC before beginning the threading operation. Use appropriate cutting fluid for the workpiece material to promote chip evacuation and extend tool life. Inspect the tap for wear or damage before each use and never force a tap against excessive resistance.