Import BDNA-20730 Straight Flute Tap 7/8-9 Unc Hss

Product Description

The IMPORT BDNA-20730 is a straight flute tap designed to cut 7/8-9 UNC internal threads in through-holes and blind holes where chip evacuation is straightforward. Built from high-speed steel with a gold oxide coating, this tap offers improved lubricity and resistance to heat buildup during threading operations. The taper chamfer on the leading end distributes cutting load gradually across the first several threads, reducing the torque required to start the cut. With four flutes and an H4 thread limit, it suits moderate-tolerance threading work in ferrous metals, cast iron, and similar materials. Machinists, tool-and-die workers, and maintenance technicians install this tap in manual tap handles or machine tapping setups.

This tap is suited for right-hand 7/8-9 UNC threading applications in general manufacturing, maintenance, repair, and overhaul environments. The taper chamfer style makes it a common choice for starting threads in new holes or when tapping manually, where a gradual lead-in reduces the risk of tap breakage. The H4 thread limit positions it for use in standard tolerance applications requiring a Class 2B or Class 3B fit.

Key Features

• Thread size 7/8-9 UNC for standard unified coarse pitch threading
• Taper chamfer distributes cutting load over the lead threads for easier start
• High-speed steel construction handles heat and wear in production tapping
• Gold oxide coating reduces friction and improves cutting performance
• H4 thread limit suits standard Class 2B and Class 3B tolerance fits
• Four flutes provide adequate chip clearance in through-hole and shallow blind-hole applications

Compatibility

Designed as a standard 7/8-9 UNC straight flute taper tap compatible with manual tap handles, T-handle wrenches, and machine tapping attachments sized for this shank diameter and square drive.

Installation Notes

This tap is installed by machinists and maintenance technicians using a tap wrench, T-handle, or machine tapping setup. Always apply cutting fluid appropriate for the workpiece material before and during tapping to reduce heat and extend tool life. Ensure the hole is drilled to the correct tap drill diameter for 7/8-9 UNC before starting. Back the tap off periodically when hand-tapping to break chips and prevent binding.