Import BDNA-20707 Straight Flute Tap 5/16-18 Unc Hss

Product Description

The IMPORT BDNA-20707 is a straight flute plug tap designed to cut 5/16-18 UNC internal threads in through-holes and open-ended blind holes. Built from high-speed steel (HSS) with a gold oxide coating, it delivers solid wear resistance and reduced friction during hand or machine tapping operations. The plug chamfer — typically 3 to 5 threads — allows the tap to start easily in a pre-drilled hole while still cutting to near full depth. With 4 flutes and an H3 thread limit, this tap produces threads to standard tolerance for reliable fastener fit. Overall length is 2-23/32 inches. Machinists, maintenance technicians, and tool-and-die professionals reach for this style of tap for general-purpose threading across a wide range of ferrous and non-ferrous materials.

The BDNA-20707 is suited for production and maintenance threading in job shops, manufacturing facilities, and field repair environments. The 5/16-18 UNC thread form is one of the most common fastener sizes in general mechanical assemblies, HVAC equipment frames, electrical enclosures, and structural hardware. Right-hand threading matches the standard rotation of most tap handles and CNC rigid-tapping cycles. The H3 tolerance class positions the tap for use with standard class 2B fit threaded holes.

Key Features

• 5/16-18 UNC thread form — one of the most widely used coarse-thread fastener sizes
• Plug chamfer (3 to 5 threads) for easy start and near-full-depth cutting in through or open blind holes
• High-speed steel construction for durability across ferrous and non-ferrous materials
• Gold oxide coating reduces friction and provides light corrosion resistance during storage and use
• H3 thread limit for standard class 2B fit tolerance
• 4-flute design provides chip clearance and stable cutting geometry

Compatibility

Designed as a standard replacement or stock tap for 5/16-18 UNC threading applications using conventional tap handles, tap wrenches, or CNC rigid-tapping setups compatible with straight flute HSS taps.

Installation Notes

Threading operations should be performed by qualified machinists or maintenance technicians following established shop safety procedures. Always ensure the workpiece is securely fixtured before tapping. Use an appropriate cutting fluid for the material being threaded to extend tap life and improve thread finish. Inspect the tap for chipping or wear before each use — a damaged tap can seize in the hole or produce out-of-tolerance threads.