Osg 1135901 Straight Flute Tap 7/8-14 Unf 4 Flute Hss

Product Description

The OSG 1135901 is a straight flute tap designed for cutting 7/8-14 UNF internal threads in a variety of ferrous and non-ferrous materials. Built from high-speed steel with an oxide finish, this tap delivers reliable performance in production and maintenance threading applications. The bottoming chamfer allows threads to be cut close to the bottom of a blind hole, making it well suited for close-tolerance work. At 4-11/16 inches overall length with a thread length of 2-7/32 inches, the 1135901 fits standard tap holders and is appropriate for use on manual machines, drill presses, and CNC machining centers.

This tap is intended for use in materials including aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. The 4-flute straight flute geometry provides good chip control in through-hole and shallow blind-hole applications across these material types. It carries a 3B class of fit and an H4 thread limit, making it appropriate for standard tolerance threaded assemblies in industrial, maintenance, and manufacturing environments. Installation is performed by machinists and toolroom professionals on tapping machines or by hand.

Key Features

• Bottoming chamfer for threading close to the bottom of blind holes
• 4 straight flutes for consistent chip evacuation in a range of materials
• High-speed steel construction for heat and wear resistance
• Oxide finish for improved lubricity and corrosion resistance during use
• H4 thread limit with 3B class of fit for standard tolerance assemblies
• Right-hand thread direction for conventional tapping operations

Compatibility

Designed as a standard replacement or production tap for 7/8-14 UNF threading operations in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces.

Installation Notes

This tap should be installed in a properly sized tap holder or chuck rated for the shank diameter before use. Always apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread quality. Ensure the workpiece is securely fixtured and the spindle is properly aligned before beginning the threading cycle. Follow shop safety practices and manufacturer recommendations for speed and feed selection appropriate to the material being tapped.