Kennametal 4131384 Hand Tap 1/4-20 Unc Bottoming Hss

Product Description

The KENNAMETAL 4131384 is a 1/4-20 UNC straight-flute hand tap designed for cutting internal threads in through-holes and blind holes requiring a bottoming chamfer. Built from high-speed steel (HSS) with an oxide finish, this tap handles threading in cast iron, ductile iron, and steel. The 4-flute straight-flute design provides rigid cutting action and is well-suited for hand tapping operations. With an H3 thread limit and a 3B class of fit, it produces threads within the standard tolerance range for most general-purpose fastener applications. The bottoming chamfer style leaves only 1 to 2 thread leads without full form, allowing threading to the bottom of a blind hole.

This tap is used in maintenance, repair, and production threading applications across metalworking shops, toolrooms, and field repair environments. It is appropriate for ferrous materials including cast iron, ductile iron, and steel. The right-hand thread direction and UNC thread standard make it compatible with standard fractional fastener systems commonly found in industrial and mechanical assemblies. Machinists, millwrights, and maintenance technicians typically reach for this tap when a bottoming finish is required in a blind bore.

Key Features

• Bottoming chamfer for threading close to the bottom of blind holes
• High-speed steel construction for durability in ferrous materials
• Oxide finish for mild corrosion resistance and reduced friction during cutting
• 4-flute straight-flute geometry for stable, rigid thread cutting
• H3 thread limit with 3B class of fit for standard general-purpose tolerances
• Right-hand thread direction, no coolant-through requirement

Compatibility

Rated for material applications including cast iron, ductile iron, and steel. Suitable for standard 1/4-20 UNC threaded hole applications requiring a bottoming tap in those material types.

Installation Notes

This tap is installed by hand or with a tap wrench; secure the workpiece before beginning. Ensure the correct tap drill size for 1/4-20 UNC is used prior to tapping. Apply cutting fluid appropriate to the workpiece material to extend tap life and improve thread quality. Back the tap out periodically to break chips and prevent binding, especially in blind holes.