Import BDNA-20746 Straight Flute Tap 1-8 Unc Bottoming

Product Description

The IMPORT BDNA-20746 is a straight flute bottoming tap designed to cut 1-8 UNC right-hand internal threads in blind and through holes. Built from high-speed steel (HSS) with a gold oxide coating, it resists wear and reduces friction during cutting. The bottoming chamfer style allows threading to the bottom of a blind hole, making it well suited for applications where full thread depth is required close to the hole floor. Four flutes provide chip clearance and cutting stability in a range of metals and materials. Machinists and maintenance technicians reach for this tap when a threading job demands tight, bottom-of-hole thread engagement.

This tap is used in general machining, maintenance and repair, and fabrication environments where 1-8 UNC coarse-thread fasteners are standard. The 1-8 UNC designation covers large-diameter, coarse-pitch threading common in structural hardware, heavy equipment, and industrial machinery. The bottoming style makes it a follow-up tap in a standard tap set sequence, used after a taper or plug tap has started the thread, or as a standalone tool when thread runout space is minimal.

Key Features

• Bottoming chamfer cuts threads to the base of blind holes
• 1-8 UNC thread form, 8 threads per inch, right-hand direction
• High-speed steel construction handles a wide range of workpiece materials
• Gold oxide coating reduces friction and improves tool life
• 4 flutes provide chip evacuation and cutting stability
• H4 thread limit for controlled fit in standard UNC tapped holes

Compatibility

Designed as a standard 1-8 UNC bottoming tap suitable for use in manual tap handles, T-handle wrenches, and machine tapping setups that accept the appropriate square-drive shank size for this thread class.

Installation Notes

Tapping should be performed by a qualified machinist or maintenance technician. Always secure the workpiece and use a properly aligned tap handle or tapping head to prevent tap breakage. Apply cutting fluid appropriate to the workpiece material throughout the operation. For blind holes, clear chips frequently to prevent packing and tap failure.