Osg 1703908 Spiral Flute Tap 5/16-18 Unc 3 Flute

Product Description

The OSG 1703908 is a spiral flute tap designed for threading 5/16-18 UNC holes in demanding materials. It features a modified bottoming chamfer, a 2B class of fit, and a powdered metal construction with a TiCN coating for extended tool life. The 3-flute, right-hand spiral design efficiently evacuates chips upward out of the hole, making it well suited for blind-hole tapping. With an overall length of 2.938 inches and a 15-degree helix angle, this tap is built for precision threading in production and job-shop environments. Licensed machinists and tool-and-die professionals are the primary users.

This tap is intended for use in materials including alloy steel, stainless steel, hardened steel, titanium, and high-nickel alloys. The modified bottoming chamfer allows threading closer to the bottom of a blind hole than a standard plug tap, making it a practical choice where thread depth is critical. It is suited for CNC machining centers and manual tapping operations requiring consistent 2B thread tolerance across production runs.

Key Features

• 5/16-18 UNC thread form, right-hand direction, 2B class of fit
• Modified bottoming chamfer for threading close to the base of blind holes
• 3-flute right-hand spiral design promotes upward chip evacuation in blind holes
• Powdered metal substrate with TiCN coating for wear resistance in hard and abrasive materials
• 15-degree helix angle balances chip flow and cutting stability
• H5 thread limit for consistent tolerance control in precision threading applications

Compatibility

Rated for use in alloy steel, stainless steel, hardened steel, titanium, and high-nickel alloys. Designed as an OEM-style replacement or direct-use spiral flute tap for 5/16-18 UNC threading applications in standard tapping chucks and holders accepting a 0.381-inch shank diameter.

Installation Notes

This tap should be installed by a qualified machinist familiar with threading speeds, feeds, and tap holder requirements for the workpiece material. Always ensure the tap holder is properly aligned to avoid tap breakage, particularly in hardened or high-nickel alloy workpieces. Use an appropriate cutting fluid or coolant for the material being tapped; this tap does not support through-coolant. Follow shop safety procedures and machine lockout protocols before tool changes.