Osg 1703901 Spiral Flute Tap 5/16-18 Unc Modified Bottoming

Product Description

The OSG 1703901 is a spiral flute tap designed for cutting internal right-hand threads in a wide range of demanding materials. It produces a 5/16-18 UNC thread profile to a 2B class of fit, with a modified bottoming chamfer that allows threading close to the bottom of blind holes. Built from powdered metal and finished with a steam oxide coating, this tap is suited for use in alloy steel, stainless steel, hardened steel, titanium, and high-nickel alloys. The 3-flute spiral design directs chips up and out of the hole, reducing the risk of chip packing. Licensed machinists and tool-and-die tradespeople are the typical installers.

This tap is applied in precision machining environments where blind-hole tapping in hard or gummy materials is required. The modified bottoming chamfer with approximately 1 to 2 lead threads allows threading to within a few threads of the hole bottom, making it well suited for workpieces with limited thread depth. The H5 thread limit provides a controlled oversize tolerance appropriate for 2B fit assemblies. It is commonly used in production tapping operations on CNC machining centers and manual tapping setups across aerospace, industrial, and general metalworking applications.

Key Features

• 5/16-18 UNC thread form, 2B class of fit, H5 thread limit for controlled tolerance
• Modified bottoming chamfer for threading close to the base of blind holes
• 3-flute right-hand spiral design evacuates chips upward out of the hole
• Powdered metal construction for improved wear resistance in hard and abrasive materials
• Steam oxide coating reduces friction and provides light lubrication retention
• Rated for alloy steel, stainless steel, hardened steel, titanium, and high-nickel alloys

Compatibility

Designed for tapping 5/16-18 UNC right-hand threads in alloy steel, stainless steel, hardened steel, titanium, and high-nickel alloy workpieces. Part of OSG Series 313.

Installation Notes

Installation is performed by qualified machinists using a tapping head, CNC spindle, or manual tap wrench. Always ensure the tap is properly aligned to the pre-drilled pilot hole to prevent tap breakage. Apply appropriate cutting fluid for the workpiece material, especially when working with stainless steel, titanium, or high-nickel alloys. Power down and secure the workpiece before changing or inspecting taps.