Import BDNA-20737 Straight Flute Tap 1/4-20 Unc Bottoming

Product Description

The IMPORT BDNA-20737 is a straight flute bottoming tap designed for cutting internal 1/4-20 UNC right-hand threads in through-holes and blind holes where full thread depth close to the bottom of the hole is required. Manufactured from high-speed steel and finished with a gold oxide coating for added lubricity and corrosion resistance, this tap features 4 flutes and an H3 thread limit for consistent tolerance control. It is sized for 1/4-20 UNC thread standard and is suited for production and maintenance threading operations performed by machinists, pipefitters, and general trade professionals working with ferrous and non-ferrous materials.

This bottoming tap is used in applications where a taper or plug tap has already started the thread and the final pass must extend fully to the bottom of a blind hole. Common install scenarios include machine shop production runs, field repair threading on equipment, and bench work in industrial or mechanical maintenance environments. The 4-flute straight flute design is best suited for threading softer materials and shorter chipping operations.

Key Features

• 1/4-20 UNC thread size with 20 threads per inch for standard inch-series fastener compatibility
• Bottoming chamfer style allows threading to the full depth of blind holes
• High-speed steel construction provides durability across a range of workpiece materials
• Gold oxide coating improves surface lubricity and reduces galling during threading
• H3 thread limit ensures consistent fit within standard UNC tolerance ranges
• 4-flute straight flute geometry suited for short-chip and softer materials

Compatibility

Designed as a standard replacement or stock tap for 1/4-20 UNC bottoming applications across general machining, maintenance, and fabrication work. Verify hole diameter and material hardness prior to use to confirm suitability.

Installation Notes

This tap is installed by machinists or qualified trade professionals using a tap handle, T-handle wrench, or machine tapping setup. Always ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct tap drill diameter for 1/4-20 UNC threads before tapping. Apply cutting fluid appropriate for the workpiece material to extend tool life and improve thread quality. A bottoming tap should be used only after a taper or plug tap has already established the thread lead in blind hole applications.