Osg 2407903 Straight Flute Tap 1/2-20 Unf Plug Nitride Hss

Product Description

The OSG 2407903 is a straight flute machine tap designed to cut right-hand internal threads to a 1/2-20 UNF specification. Built from vanadium high-speed steel with a nitride coating, it delivers improved wear resistance and heat tolerance compared to standard uncoated HSS taps. The plug chamfer (5-6 thread lead) makes it well suited for through-hole applications where the tap can advance progressively into the workpiece. With 4 flutes and an H3 thread limit, the 2407903 holds tight tolerances for a 3B class of fit. Machinists and tool-and-die technicians are the primary users of this tap in production and maintenance environments.

This tap is intended for machine tapping operations in materials including aluminum and cast iron. The straight flute geometry works best in shorter-chipping materials where chip evacuation through the flutes is manageable. It is suited for use in CNC machining centers, drill presses, and dedicated tapping machines running with appropriate cutting fluid or coolant applied externally. Coolant-through is not available on this model. The Series 240 designation places it within OSG's standard production tap line for inch-thread applications.

Key Features

• 1/2-20 UNF right-hand thread form, 3B class of fit with H3 thread limit for controlled tolerance
• Vanadium high-speed steel construction for improved toughness and wear resistance over standard M2 HSS
• Nitride surface coating reduces friction and extends tool life in moderate-speed applications
• Plug chamfer (5-6 lead threads) optimized for through-hole tapping in production runs
• 4 straight flutes designed for short-chip materials such as aluminum and cast iron
• OSG Series 240 — a standard machine tap series for inch UNF thread forms

Compatibility

Designed for machine tapping of 1/2-20 UNF through holes in aluminum and cast iron workpieces. Suitable for use with standard tap holders and floating tap collets sized for a 0.367-inch shank diameter.

Installation Notes

Installation should be performed by a qualified machinist using a rigid or floating tap holder appropriate for the machine type. Ensure the spindle speed and feed rate match the manufacturer recommendations for the material being tapped — nitride-coated HSS taps are not intended for dry running in cast iron or hard alloys. Apply a suitable cutting fluid to the tap and workpiece before engagement. Inspect the tap for chipping or wear before each use, as a damaged tap can tear threads and damage the workpiece.