Osg 1400105400 Thread Forming Tap 4-40 Unc Cobalt

Product Description

The OSG 1400105400 is a thread forming tap designed for producing 4-40 UNC internal threads without cutting or removing material. It works by cold-forming the thread profile, which strengthens the thread form and eliminates chips in the work zone. Built from cobalt high-speed steel with a bright finish, this tap is engineered for demanding tapping applications in blind holes. It carries an H4 thread limit and a modified bottoming chamfer of 2 to 2.5 threads, making it well suited for threading close to the bottom of a blind hole. Overall length is 1.875 inches. Licensed machinists and toolroom technicians are the primary users.

This tap is part of the OSG HY-PRO NRT series, purpose-built for blind hole threading in a range of metallic workpiece materials. It handles alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The modified bottoming chamfer allows the tap to begin forming threads very close to the bottom of a drilled hole, which is critical in tight-tolerance machining work. It is commonly used in CNC machining centers, drill presses, and manual tapping setups where chip-free thread forming is preferred over conventional cutting taps.

Key Features

• Thread forming design eliminates chips and strengthens formed threads
• Cobalt construction provides heat and wear resistance in hard or abrasive materials
• Modified bottoming chamfer (2 to 2.5 threads) enables threading near the bottom of blind holes
• H4 thread limit for consistent fit class control in 4-40 UNC applications
• Right-hand thread direction, standard for UNC tooling
• No coolant-through requirement simplifies setup on standard tapping equipment

Compatibility

Designed for blind hole threading in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Part of the OSG HY-PRO NRT series (Series 14001) for 4-40 UNC thread forming applications.

Installation Notes

Thread forming taps require a properly sized forming tap drill hole, which is larger than a cutting tap drill — consult OSG or standard thread forming drill charts for the correct pilot hole diameter before tapping. Apply a suitable tapping fluid or cutting oil rated for the workpiece material to reduce galling and extend tap life. Secure the workpiece and tap driver to prevent tap breakage, especially at small diameters like 4-40. Follow shop safety practices and machine tool manufacturer guidelines when setting spindle speed and feed rate for thread forming operations.