Value Collection JY4870218 Straight Flute Tap 1-1/4-20 Uns

Product Description

The VALUE COLLECTION JY4870218 is a straight flute bottoming tap designed to cut internal threads in pre-drilled holes where thread engagement must extend close to the bottom of a blind bore. Manufactured from high-speed steel with a bright/uncoated finish, it produces a 1-1/4-20 UNS right-hand thread to a 3B class of fit with an H4 thread limit. The 6-flute design distributes cutting load across more edges than a standard 4-flute tap, reducing chatter and improving thread finish in moderate-to-hard workpiece materials. Overall length is 4 inches. This tap is suited for use by machinists and maintenance trades working with UNS-specified thread callouts.

This tap is intended for threading applications requiring a bottoming chamfer, meaning it begins cutting threads within 1 to 2 thread pitches of the bottom of a blind hole. It is appropriate for general metalworking, maintenance, repair, and overhaul work where UNS thread forms are specified. The H4 thread limit provides a controlled oversize tolerance to account for material springback in tougher metals. Applications include tapping threaded holes in steel, cast iron, and similar materials in industrial, mechanical, and trade-shop environments.

Key Features

• Bottoming chamfer allows threading to within 1-2 pitches of a blind hole bottom
• 6-flute configuration reduces cutting load per flute and improves thread surface finish
• High-speed steel construction provides durability across a range of ferrous and non-ferrous workpiece materials
• H4 thread limit accommodates material springback in harder metals
• 3B class of fit meets standard internal thread tolerance requirements
• Right-hand thread direction, bright/uncoated finish, no coolant-through feature

Compatibility

Designed for cutting 1-1/4-20 UNS internal threads in applications where a bottoming tap and 3B class of fit are specified. No specific compatible model or system information was provided for this product.

Installation Notes

This tap is installed and operated by machinists or maintenance technicians using a tap wrench, tapping head, or CNC machine tool with appropriate tap holders. The workpiece should be securely fixtured before tapping begins. Use a cutting fluid appropriate for the workpiece material to extend tap life and improve thread quality. Inspect the starting chamfer of the tap before each use and replace immediately if chipping or wear is observed, as a damaged bottoming tap can seize in a blind hole.