Hertel K008650AS 1-1/8-7 Unc Bottoming Tap 4 Flutes Hss

Product Description

The HERTEL K008650AS is a straight flute bottoming tap designed for cutting unified coarse (UNC) internal threads in a 1-1/8-7 thread size. With four straight flutes and a bottoming chamfer, this tap cuts threads to the bottom of blind holes where a plug or taper tap cannot reach. It is manufactured from high speed steel (HSS) with a bright, uncoated finish. At 5.4375 inches overall length and weighing 0.85 pounds, it is sized for use in production and job-shop environments. The H4 thread limit and Class 3B fit designation make it suitable for precision threading applications where tighter tolerances are required. Machinists and tool-and-die professionals are the primary users of this tool.

This tap is used in metalworking and machining applications where a coarse 1-1/8-7 UNC thread must be cut to the bottom of a blind hole. Typical scenarios include threading bored holes in steel, cast iron, aluminum, and similar machinable materials on manual lathes, drill presses, or CNC machining centers. The straight flute geometry works best in through holes and short blind holes in materials that produce broken chips. The bottoming chamfer, which has approximately 1 to 2 lead threads, allows the tap to thread as close to the bottom of a hole as possible after initial threading with a taper or plug tap.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• 1-1/8-7 UNC thread size with Class 3B fit for precision thread tolerances
• H4 thread limit for controlled oversize tolerance in finished threads
• 4 straight flutes for efficient chip clearing in short-chipping materials
• High speed steel construction for durability across a range of machinable metals
• Bright, uncoated finish suitable for general-purpose threading applications

Compatibility

Designed as an OEM-style replacement or direct tooling selection for machines requiring a 1-1/8-7 UNC bottoming tap with a standard shank profile compatible with tap holders and tapping heads sized for large-diameter taps.

Installation Notes

This tap is installed and operated by machinists using a tap wrench, tapping fixture, or power tapping head. Ensure the workpiece is securely clamped and the tap is aligned perpendicular to the hole before starting. Use an appropriate cutting fluid for the workpiece material to reduce friction and extend tool life. Never force a tap against the bottom of a blind hole without confirming adequate chip clearance, as breakage may occur.