Kennametal 4129998 Hand Tap 1-1/4-7 Unc Bottoming Hss

Product Description

The KENNAMETAL 4129998 is a straight-flute hand tap designed for cutting 1-1/4-7 UNC internal threads in a bottoming configuration. Manufactured from high-speed steel with a bright, uncoated finish, it is built for threading operations where the tap must cut close to the bottom of a blind hole. The 4-flute design provides even chip distribution and thread accuracy. With an overall length of 5.75 inches and a thread length of 2.563 inches, this tap is sized for production and maintenance threading in metalworking environments. It carries a Class of Fit 3B and Thread Limit H4 for consistent, tolerance-controlled thread output. Licensed machinists, toolroom technicians, and maintenance mechanics are the primary users.

This tap is suited for hand tapping operations in cast iron and non-ferrous metals. The bottoming chamfer allows threading to within one to two threads of the bottom of a blind hole, making it the correct choice when full thread depth is required near the hole base. It is commonly used in repair, fabrication, and production environments where UNC 1-1/4-7 threads must meet 3B fit tolerance. Part of the KENNAMETAL Series 5305 and 5303 tap families.

Key Features

• Bottoming chamfer for threading close to the bottom of blind holes
• High-speed steel construction for durability across cast iron and non-ferrous metal applications
• 4-flute straight flute design for even chip load and thread consistency
• Bright, uncoated finish — no coating buildup to affect thread tolerance
• Class of Fit 3B, Thread Limit H4 for controlled tolerance output
• Right-hand thread direction, standard UNC thread form

Compatibility

Designed for 1-1/4-7 UNC threading applications in cast iron and non-ferrous metals. Compatible with standard tap wrenches and machine holders sized for a 1.021-inch shank diameter. Part of KENNAMETAL Series 5305 and 5303.

Installation Notes

This tap is intended for use by qualified machinists or maintenance technicians. Before use, secure the workpiece and ensure the tap wrench or holder is properly sized for the 1.021-inch shank. Apply appropriate cutting fluid for the workpiece material to reduce wear and improve thread finish. Inspect the tap for damage before each use — a chipped or worn tap in a blind hole can result in breakage and workpiece loss.