Osg 1400128605 Thread Forming Tap 1/4-28 Unf Cobalt Tin

Product Description

The OSG 1400128605 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal 1/4-28 UNF threads without cutting. Rather than removing material, it displaces it to produce stronger, work-hardened threads with no chips to clear. The modified bottoming chamfer — 2 to 2.5 thread pitches — allows threading close to the bottom of a blind hole. Built from cobalt high-speed steel with a TiN coating, this tap handles the heat and abrasion generated in demanding materials. The H6 thread limit ensures the formed threads fall within the upper range of standard tolerance, accommodating the slight spring-back that occurs after forming.

This tap is rated for blind hole threading in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. It is well suited to production machining and precision fabrication environments where thread quality, hole strength, and chip-free operation are priorities. At 2.5 inches overall length with a shank diameter of 0.255 inches and a square drive of 0.191 inches, it fits standard tapping heads and CNC rigid-tap toolholders used in machine shops and manufacturing facilities.

Key Features

• Thread forming (chipless) design strengthens threads by cold-working the material rather than cutting
• Modified bottoming chamfer (2 to 2.5P) for threading close to the bottom of blind holes
• Cobalt high-speed steel construction for elevated heat resistance in tough alloys and stainless steel
• TiN coating reduces friction and extends tool life across high-volume tapping applications
• H6 thread limit accommodates material spring-back for consistent UNF thread fit
• Right-hand thread direction; no coolant-through requirement simplifies setup

Compatibility

Designed for blind hole threading in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel (material application codes P and N). Fits standard tapping chucks and rigid-tap holders accepting a 0.255-inch shank with a 0.191-inch square drive.

Installation Notes

Thread forming taps require a specific forming tap drill size — do not use the same drill size as a cutting tap for the same thread. Secure the workpiece and ensure the tap is aligned axially to the hole before engagement. Use an appropriate tapping fluid or cutting oil rated for the workpiece material, particularly when working with stainless steel or hardened alloys. Follow machine shop safety practices and consult applicable OSHA standards for rotating tooling when operating in powered tapping equipment.