Osg 2948801 Spiral Flute Tap 9/16-18 Unf Vanadium Hss

Product Description

The OSG 2948801 is a spiral flute tap designed for cutting 9/16-18 UNF right-hand internal threads in ferrous materials. Built from 3% Vanadium High-Speed Steel with a steam oxide coating, it resists wear and runs cooler in demanding threading applications. The 4-flute spiral design with a 45-degree helix angle evacuates chips upward out of blind holes, making it well-suited for modified bottoming work where thread depth is critical. Overall length is 3-19/32 inches, with a shank diameter of 0.168 inches. Thread limit is H3, providing controlled oversize tolerance for standard-fit threaded assemblies. Licensed machinists, tool-and-die makers, and maintenance technicians are the primary users of this tap.

This tap is intended for threading alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. The modified bottoming chamfer allows threads to be cut close to the bottom of a blind hole without fully bottoming, balancing reach with cutting stability. Series 290 from OSG is a general-purpose spiral flute line suited for production and maintenance threading in manual or CNC-tapping operations. Thread length is 0.665 inches, and neck length is 0.826 inches, giving adequate clearance in most standard tap holder setups.

Key Features

• 4-flute spiral design with 45-degree helix angle for upward chip evacuation in blind holes
• 3% Vanadium High-Speed Steel construction for improved wear resistance over standard HSS
• Steam oxide coating reduces friction and provides light corrosion resistance
• Modified bottoming chamfer allows threading close to the base of blind holes
• H3 thread limit for controlled oversize fit on 9/16-18 UNF threads
• Right-hand flute direction and right-hand thread for standard tapping operations

Compatibility

Designed for cutting 9/16-18 UNF right-hand threads in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel workpieces using standard straight-shank tap holders sized for a 0.168-inch shank diameter.

Installation Notes

Install in a tap holder or chuck rated for the shank diameter before use; secure all workpieces firmly before beginning the threading operation. Apply a suitable tapping fluid for the workpiece material, particularly when threading stainless or hardened steel, to extend tap life and improve thread finish. Inspect the tap for chipping or wear before each use; a damaged tap can seize or break in the hole. Follow applicable shop safety practices and machine manufacturer guidelines for spindle speed and feed rate selection.