Import BDNA-20790 Straight Flute Tap 7/16-20 Unf Bottoming

Product Description

The IMPORT BDNA-20790 is a straight flute bottoming tap designed for cutting 7/16-20 UNF right-hand internal threads in blind and through holes. Built from high-speed steel (HSS) with a gold oxide coating, this tap provides improved lubricity and surface hardness for extended tool life in production and maintenance threading applications. The bottoming chamfer style — with only 1 to 2 threads of taper — allows threading to the bottom of blind holes where plug or taper taps cannot reach. The 4-flute design provides good chip control and thread finish in a range of machinable materials. Thread limit is H3, indicating a tolerance suited to Class 2B and Class 3B fit assemblies.

This tap is used in machine shops, maintenance facilities, and manufacturing environments where 7/16-20 UNF threaded holes are required. Common applications include repair threading of existing blind holes, threading fixture components, and production threading of steel, aluminum, brass, and similar materials. It is appropriate for use in manual tapping operations as well as low-speed machine tapping setups. Licensed machinists and maintenance technicians are the primary users.

Key Features

• Bottoming chamfer allows threading to the full depth of blind holes
• High-speed steel construction withstands heat generated during threading operations
• Gold oxide coating reduces friction and improves tap longevity
• 4-flute configuration promotes chip control and clean thread finish
• H3 thread limit suitable for Class 2B and Class 3B UNF fit requirements
• Right-hand thread direction, 20 threads per inch, 7/16-20 UNF specification

Compatibility

Designed as an OEM-style replacement or production tap for any application requiring a 7/16-20 UNF internal thread in machinable metals and plastics.

Installation Notes

Always secure the workpiece and use a properly aligned tap wrench or tapping head to avoid tap breakage. Apply cutting fluid appropriate to the workpiece material before and during tapping. For blind holes, clear chips frequently by backing out the tap to prevent chip packing and tap failure. Inspect the tap for wear or chipping before each use and replace if thread quality is compromised.