Import BDNA-20742 Bottoming Tap 9/16-12 Unc Hss

Product Description

The IMPORT BDNA-20742 is a straight flute bottoming tap designed to cut 9/16-12 UNC internal threads to the bottom of a blind hole. Built from high-speed steel (HSS) with a gold oxide coating, this tap provides added lubricity and surface hardness for improved performance in ferrous and non-ferrous metals. The bottoming chamfer allows threading to within one or two threads of a hole's bottom, making it well suited for applications where thread engagement depth is critical. With four flutes and an H3 thread limit, this tap maintains tight dimensional control through the threading operation.

This tap is used in machine shops, maintenance facilities, and production environments where accurate UNC threads are required in blind holes. It is appropriate for use in drill press, milling machine, or hand-tapping setups when the application calls for a bottoming chamfer. Machinists, tool-and-die makers, and maintenance technicians working with steel, cast iron, aluminum, and similar materials will find this tap suitable for general-purpose thread repair and new-hole threading tasks.

Key Features

• Bottoming chamfer allows threading to the base of blind holes
• 9/16-12 UNC thread form for standard unified coarse-thread applications
• High-speed steel construction handles a wide range of metal workpieces
• Gold oxide coating improves lubricity and reduces galling during cutting
• H3 thread limit provides controlled dimensional tolerance for consistent fit
• Four-flute design balances chip clearance and cutting support

Compatibility

Designed as an OEM-style straight flute bottoming tap for use in standard 9/16-12 UNC tapping applications across general metalworking and maintenance operations.

Installation Notes

Tapping should be performed by a qualified machinist or maintenance technician using a properly aligned tap wrench, drill press, or tapping head. Ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct tap drill diameter for 9/16-12 UNC before beginning. Apply cutting fluid appropriate to the workpiece material to reduce heat and extend tap life. Reverse the tap periodically to break chips and prevent tap breakage, particularly in deeper blind holes.