Hertel K010369AS Thread Forming Tap 1/4-20 Unc Bottoming Hss

Product Description

The HERTEL K010369AS is a thread forming tap designed for blind hole threading in 1/4-20 UNC applications. Unlike cutting taps, thread forming taps displace material rather than cut it, producing stronger threads with no chips to clear from the hole. This tap is made from high-speed steel with a bright uncoated finish and features a bottoming chamfer of 1 to 2 threads, making it well-suited for threading close to the bottom of a blind hole. Overall length is 2.5 inches, with a thread length of 1 inch and a shank diameter of 0.255 inches. It is installed by machinists, tool and die makers, and maintenance technicians working with ferrous and non-ferrous metals.

This tap is used in production and maintenance environments where blind hole threading is required and thread quality is critical. The bottoming chamfer allows the tap to form threads as close to the bottom of the hole as possible, which is especially useful in short-blind-hole situations. The H4 thread limit designation indicates the tolerance class of the formed thread, guiding selection for close-tolerance work. Typical applications include fixture fabrication, machine component repair, and production threading in metals compatible with thread forming.

Key Features

• Bottoming chamfer with 1 to 2 chamfered threads for threading close to hole bottom
• Thread forming design displaces material, producing chip-free, stronger threads
• High-speed steel construction for durability across a range of metalworking applications
• H4 thread limit for consistent tolerance control in close-fit threading
• Right-hand thread direction, standard UNC specification
• Bright uncoated finish suitable for use with cutting fluids

Compatibility

Designed as an OEM-style replacement or direct-use thread forming tap for 1/4-20 UNC blind hole threading applications in compatible materials.

Installation Notes

Thread forming taps require a larger pilot hole diameter than cutting taps - consult a thread forming drill chart for the correct hole size before tapping. Apply appropriate cutting or forming fluid for the workpiece material to reduce friction and extend tap life. Secure the workpiece firmly and use a calibrated tap wrench or machine tapping setup to maintain proper alignment. Follow applicable shop safety practices and machine guarding requirements during all tapping operations.