Osg 1135400 Straight Flute Tap 7/8-9 Unc Taper Hss

Product Description

The OSG 1135400 is a straight flute tap designed to cut 7/8-9 UNC internal threads in a wide range of ferrous and non-ferrous materials. It features a taper chamfer for easy thread starting, four flutes for chip evacuation, and a bright uncoated high-speed steel construction. The H4 thread limit holds close tolerances for a 3B class of fit, making it suitable for precision threading applications in machine shops, maintenance environments, and production settings. Overall length is 4-11/16 inches with a thread length of 2-7/32 inches. This tap is installed by machinists, toolmakers, and maintenance technicians using standard tapping equipment.

This tap is suited for threading operations in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. The taper chamfer makes it a practical choice for through-hole applications and for starting threads in blind holes where a gradual thread engagement is acceptable. It performs well in both manual tapping and machine tapping setups where coolant-through capability is not required.

Key Features

• 7/8-9 UNC thread form with taper chamfer for controlled thread starting
• Four straight flutes provide chip clearance across a broad range of workpiece materials
• H4 thread limit ensures consistent 3B class of fit tolerances
• High-speed steel construction offers good wear resistance at standard cutting speeds
• Bright uncoated finish suitable for use with cutting fluids on steel and aluminum
• Right-hand thread direction; compatible with standard tapping attachments and tap wrenches

Compatibility

Designed for use in standard tapping operations on aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. Compatible with standard 7/8-9 UNC tap holders and tapping attachments. Part of OSG Series 101.

Installation Notes

Machinists and toolmakers should ensure the workpiece is securely fixtured and the tap is properly aligned with the drilled hole before beginning the threading operation. Power down or disengage the spindle before changing taps. Apply an appropriate cutting fluid for the workpiece material to extend tool life and improve thread quality. Do not reverse the tap abruptly under load, as this can cause breakage in harder materials.