Import BDNA-20743 Straight Flute Tap 5/8-11 Unc

Product Description

The IMPORT BDNA-20743 is a straight flute bottoming tap designed for cutting right-hand internal threads in pre-drilled through or blind holes. Built from high-speed steel with a gold oxide coating, this tap is engineered for thread-cutting operations where the tool must reach close to the bottom of a blind hole. It features a 4-flute straight-flute geometry, a 5/8-11 UNC thread profile, and an H3 thread limit for consistent tolerance control. The bottoming chamfer provides minimal lead-in, allowing threads to be cut within one to two thread lengths of the hole bottom. Machinists and maintenance technicians use this tap in manual and machine tapping applications across ferrous and non-ferrous materials.

This tap is suited for production and repair threading work in machine shops, industrial maintenance environments, and manufacturing operations. The 5/8-11 UNC designation makes it appropriate for standard unified coarse-thread applications, commonly found in structural fastening, equipment assembly, and fixture fabrication. The bottoming style is the correct choice when a through tap or plug tap has already been used to start threads and final full-depth threading is needed at the bottom of a closed hole.

Key Features

• 5/8-11 UNC thread profile with right-hand thread direction
• Bottoming chamfer for threading close to the bottom of blind holes
• 4 straight flutes for chip management in manual and machine tapping
• High-speed steel construction for durability across a range of workpiece materials
• Gold oxide coating helps reduce friction and provides light corrosion resistance
• H3 thread limit ensures consistent thread tolerance for standard UNC fits

Compatibility

Designed as a standard-style replacement or service tap for 5/8-11 UNC bottoming thread applications in manual tap handles, T-handle wrenches, and compatible machine tapping heads.

Installation Notes

This tap is installed by a machinist or maintenance technician using a tap wrench, T-handle, or machine tapping attachment. Ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct tap drill size for 5/8-11 UNC threads before beginning. Apply appropriate cutting fluid for the workpiece material to reduce heat and extend tool life. When using a bottoming tap, a plug or taper tap should be used first to establish threads before the bottoming tap is run in to complete the thread depth.