Kennametal 4131291 Hand Tap 1/4-20 Unc Bottoming Hss

Product Description

The KENNAMETAL 4131291 is a straight-flute hand tap designed for cutting internal threads in through-holes and blind holes where a bottoming chamfer is required. Built from high-speed steel with a bright, uncoated finish, this tap cuts 1/4-20 UNC right-hand threads to a 3B class of fit with an H3 thread limit, making it suitable for applications that require close thread tolerances. The straight flute geometry is well matched to short-chipping materials. With a 2.5-inch overall length and a 1-inch thread length, this tap is sized for general-purpose hand tapping operations in a variety of shop and field settings. Installation is performed by a machinist or skilled tradesperson using a standard tap wrench.

This tap is used in metalworking applications involving cast iron and non-ferrous metals, including aluminum, brass, and copper alloys. The bottoming chamfer - typically 1 to 2 threads of taper - allows threading to the bottom of a blind hole after a plug or taper tap has already started the thread. Typical applications include repair tapping, fixture work, and production threading where full thread depth in a blind hole is required. It carries the Series 5305 and 5303 designations from KENNAMETAL.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• High-speed steel construction for durability across cast iron and non-ferrous metals
• Bright, uncoated finish suited to general-purpose tapping
• 3-flute straight flute geometry for short-chipping materials
• 3B class of fit with H3 thread limit for close-tolerance threads
• Right-hand, 1/4-20 UNC thread form

Compatibility

Compatible with cast iron and non-ferrous metals per manufacturer specification. Intended for use in applications requiring 1/4-20 UNC internal threads to a 3B class of fit. Part of KENNAMETAL Series 5305 and 5303.

Installation Notes

Hand taps of this type are installed using a standard tap wrench and require a properly sized tap drill hole prior to use. For blind holes, a taper or plug tap should be used first to start the thread before switching to this bottoming tap. Apply cutting fluid appropriate to the workpiece material to extend tool life and improve thread quality. Follow standard shop safety practices and secure the workpiece before tapping.