Hertel K008660AS 1-1/4-7 Unc Straight Flute Tap Hss

Product Description

The HERTEL K008660AS is a straight flute hand tap designed to cut 1-1/4-7 UNC internal threads in a wide range of materials. Built from high speed steel (HSS) with a bright uncoated finish, this tap delivers reliable performance in general-purpose threading applications. It features a taper chamfer for easy thread starting and four flutes for efficient chip clearance. The overall length is 5.75 inches, and the H4 thread limit ensures consistent tolerance control for Class 3B fits. It is installed by machinists, maintenance mechanics, and tool-and-die professionals working in manufacturing, MRO, and repair environments.

This tap is suited for through-hole and blind-hole threading in ferrous and non-ferrous metals where a straight flute design is appropriate. The taper chamfer, typically 8 to 10 threads long, makes it the first tap used in a threading sequence when starting a new hole. The 1-1/4-7 UNC thread size is common in heavy machinery, structural fastener applications, and large-diameter pipe fittings. Right-hand thread direction follows standard practice for the majority of UNC threaded assemblies.

Key Features

• 1-1/4-7 UNC thread form with Class 3B fit tolerance
• H4 thread limit for tight tolerance control
• Taper chamfer for easy thread engagement and starting
• 4 straight flutes for chip clearance in through-hole applications
• High speed steel construction for general-purpose cutting performance
• Bright uncoated finish suitable for use with cutting fluids

Compatibility

Designed as an OEM-style replacement or standard production tap for use in any manual or machine tapping operation requiring a 1-1/4-7 UNC straight flute taper tap with an H4 thread limit and Class 3B fit.

Installation Notes

This tap is installed by machinists or maintenance technicians using a tap wrench or machine tapping fixture. Always use a cutting fluid appropriate to the workpiece material to reduce heat and extend tool life. Secure the workpiece firmly before tapping and align the tap perpendicular to the hole to prevent thread misalignment or tap breakage. Do not apply excessive force if the tap binds — back off to clear chips before continuing.