Osg 0143901 Extension Tap 8-32 Spiral Flute Bottoming

Product Description

The OSG 0143901 is a spiral flute extension tap designed for threading operations in tight or deep-access applications where a standard-length tap cannot reach. Built from vanadium high-speed steel with a steam oxide finish, it cuts 8-32 UNC threads in a right-hand direction with a bottoming chamfer, making it suited for threading to the bottom of blind holes. The 30-degree helix angle promotes chip evacuation up and out of the flute. It carries an H3 thread limit and a 2B class of fit, delivering consistent thread tolerance for general mechanical fastening. Licensed machinists and toolroom professionals are the typical users.

This tap is intended for use in materials including carbon steel and stainless steel. The bottoming chamfer allows threading as close to the bottom of a blind hole as possible, which is common in precision machining, tooling, and component assembly work. The reduced shank design and extended overall length of 6 inches give access to recessed or deep-hole features that standard extension taps cannot service. With 3 flutes and a spiral flute geometry, it handles interrupted cuts and chip clearing in through and blind hole applications.

Key Features

• Spiral flute geometry with 30-degree helix angle for upward chip evacuation in blind holes
• Bottoming chamfer allows threading to the full depth of blind holes
• Vanadium high-speed steel construction for wear resistance in carbon steel and stainless steel
• Steam oxide finish reduces friction and provides light corrosion resistance during use
• Reduced shank and 6-inch overall length extend reach into deep or recessed features
• H3 thread limit and 2B class of fit for consistent, tolerance-compliant thread production

Compatibility

Designed for threading 8-32 UNC right-hand threads in carbon steel and stainless steel workpieces. Suited for use in standard drill press, CNC, or tapping machine setups accepting a 0.168-inch shank diameter.

Installation Notes

This tap should be installed and operated by a qualified machinist familiar with tapping speeds, feeds, and cutting fluid requirements for the workpiece material. Always ensure the spindle and workpiece are properly secured and aligned before starting. Use appropriate cutting fluid for the material being tapped to maximize tool life and thread quality. Do not exceed the recommended torque capacity for the tap size, and back off periodically to break and clear chips when tapping blind holes.