Kennametal 1542145 Hand Tap 1/4-20 Unc Plug 4-flute Hss

Product Description

The KENNAMETAL 1542145 is a straight-flute hand tap designed for cutting 1/4-20 UNC internal threads in a wide range of workpiece materials. Built from high-speed steel (HSS) with a bright, uncoated finish, it delivers reliable thread-forming performance in cast iron and non-ferrous metals. The plug chamfer — 3 to 5 threads of lead — makes it suitable for through-hole applications where the tap can advance progressively through the work. With 4 flutes and an H2 thread limit, this tap holds tight tolerances for standard commercial threading work. Overall length is 2.5 inches, and thread length is 1 inch. It is used by machinists, maintenance mechanics, and tool-and-die tradespeople working in manual tapping operations.

This tap is suited for hand-tapping operations on cast iron components and non-ferrous metals such as aluminum, brass, and copper alloys. The straight-flute design makes it appropriate for through-holes and shorter blind holes where chip clearance is manageable by reversing the tap. The H2 thread limit provides a tolerance range that works well with standard class 2B threaded hole requirements common in general manufacturing, maintenance, and repair applications. It is sold individually and fits standard tap wrench collets sized for the 0.255-inch shank diameter.

Key Features

• 1/4-20 UNC thread form, right-hand cutting direction
• Plug chamfer (3-5 thread lead) for through-hole and open blind-hole threading
• 4-flute straight-flute geometry suited for cast iron and non-ferrous metals
• H2 thread limit for standard class 2B fit tolerances
• High-speed steel construction with bright (uncoated) finish
• 0.255-inch shank diameter fits standard tap wrenches and holders

Compatibility

Designed for use in standard hand-tapping applications requiring 1/4-20 UNC threads. Listed under KENNAMETAL Series 5305 and 5303. Compatible with tap wrenches and holders accepting a 0.255-inch shank diameter.

Installation Notes

Hand taps should be installed and driven using a properly sized tap wrench to maintain axial alignment with the pilot hole. Ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct tap-drill diameter for 1/4-20 UNC before starting. Apply appropriate cutting fluid for the workpiece material to extend tap life and improve thread quality. Back the tap off periodically to break chips and prevent binding, especially in deeper holes.