Osg 2493503 Straight Flute Tap 1/4-28 Unf Plug 3B Hss

Product Description

The OSG 2493503 is a straight flute machine tap designed for cutting 1/4-28 UNF internal threads in through-hole and blind-hole applications. Built from vanadium high-speed steel with a nitride coating, it offers improved wear resistance and surface hardness compared to standard HSS taps. The plug chamfer configuration distributes cutting load across several leading threads, making it well suited for general-purpose tapping where hole depth is not severely restricted. With an overall length of 2.5 inches and a thread length of 0.594 inches, this tap fits standard tap holders and machines used in production and maintenance environments. Licensed machinists and toolroom technicians are the primary users.

This tap is rated for 3B class of fit with an H3 thread limit, producing threads within standard tolerance for most fastener and assembly applications. It is suited for use in aluminum and cast iron workpieces. The right-hand thread direction and straight flute geometry make it appropriate for machine tapping operations where chip evacuation can be managed by the application setup. It is commonly used in CNC machining centers, drill presses with tapping attachments, and manual tapping fixtures across job shop and production environments.

Key Features

• 1/4-28 UNF thread form with plug chamfer for general-purpose through and blind-hole tapping
• Vanadium high-speed steel construction for enhanced toughness and tool life
• Nitride coating improves surface hardness and reduces galling, especially in aluminum
• 3B class of fit with H3 thread limit for standard tolerance internal threads
• 3-flute straight geometry provides stability in short-chipping materials such as cast iron
• Right-hand thread direction; no coolant-through feature

Compatibility

Designed for use in aluminum and cast iron workpieces requiring 1/4-28 UNF internal threads. Part of OSG Series 240.

Installation Notes

This tap should be installed by a qualified machinist following standard tapping procedures. Ensure the workpiece is securely fixtured and the spindle is properly aligned before engaging the tap. Power down and de-energize any machine tool before changing or inspecting tooling. Use an appropriate cutting fluid for the workpiece material to maximize tool life and thread quality.