Value Collection JY4838751 Hand Tap 12-40 Uns Bottoming Hss

Product Description

The VALUE COLLECTION JY4838751 is a bottoming hand tap designed for cutting 12-40 UNS internal threads in through-holes and blind holes where full thread depth is required close to the bottom. Manufactured from high speed steel (HSS) with a bright, uncoated finish, this tap delivers consistent thread form across a range of workpiece materials. It features a 4-flute straight flute geometry and a right-hand thread direction. The overall length is 2-3/8 inches, and it is ground to a Class 3B fit with an H2 thread limit for close-tolerance threading work. Machinists, toolmakers, and maintenance technicians are the typical users.

This tap is suited for hand tapping operations in machine shops, maintenance and repair environments, and production settings where 12-40 UNS threads are specified. The bottoming chamfer — typically 1 to 2 thread leads — allows threading to within one or two threads of a blind hole bottom. It is used after a taper or plug tap has started the thread, completing the thread profile at full depth. Applications include fastener holes in precision assemblies, jigs, fixtures, and tooling components where the UNS thread standard applies.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• High speed steel construction for durability across common workpiece materials
• Bright, uncoated finish suitable for general-purpose hand tapping
• 4-flute straight flute design for balanced cutting action and chip clearance
• Class 3B fit with H2 thread limit for close-tolerance internal threads
• Right-hand thread direction, 12-40 UNS thread form

Compatibility

Designed for cutting 12-40 UNS internal threads. Intended for use with a standard tap wrench or T-handle for hand tapping operations. Typically used as the final tap in a taper-plug-bottoming tap sequence for blind holes.

Installation Notes

This tap is installed using a tap wrench sized appropriately for the square shank drive. Secure the workpiece before tapping and apply cutting fluid to reduce heat and extend tap life. Use moderate, consistent torque and back off periodically to break chips. Inspect the tap for wear or chipping before each use — a damaged tap can seize in the hole and cause the tap to break.