Osg 1120705 Straight Flute Tap 5/16-18 Unc Tin Hss

Product Description

The OSG 1120705 is a straight flute tap designed to cut 5/16-18 UNC internal threads in a wide range of metallic workpiece materials. Built from high-speed steel (HSS) and finished with a titanium nitride (TiN) coating, it delivers extended tool life compared to uncoated HSS taps. The plug chamfer provides a gradual thread lead-in suited to through-hole and most blind-hole applications. With 4 flutes and an H3 thread limit, this tap holds tight tolerances for a 3B class of fit, making it appropriate for precision fastener assemblies and production work. Overall length is 2-23/32 inches and thread length is 1-1/8 inches.

This tap is used in machine shop, maintenance, and fabrication environments where 5/16-18 UNC threads are required. It is suited for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The straight flute geometry is well-suited to through-hole tapping and to brittle materials where chip evacuation direction is less critical. It is installed in a tapping head, CNC machine, or manual tap handle depending on the application and production volume.

Key Features

• 5/16-18 UNC thread form with 4 straight flutes for stable cutting in ferrous and non-ferrous materials
• TiN coating increases surface hardness and reduces friction for longer tool life
• Plug chamfer allows gradual thread engagement in through-holes and most blind holes
• H3 thread limit holds 3B class of fit tolerances for standard fastener assemblies
• High-speed steel construction suitable for a broad range of material applications
• Right-hand thread direction; no coolant-through feature required for general-purpose use

Compatibility

Designed as an OEM-style replacement or direct substitute for standard 5/16-18 UNC straight flute plug taps in Series 101 applications. Compatible with aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces.

Installation Notes

This tap should be installed by a machinist or qualified tool operator familiar with threading operations. Always secure the workpiece and ensure the tapping tool is properly aligned to avoid tap breakage. Apply appropriate cutting fluid for the workpiece material, particularly when working with steel. Follow shop safety procedures and machine manufacturer guidelines when operating tapping equipment.