Osg 1400158908 Thread Forming Tap 1/4-20 Unc Cobalt Ticn

Product Description

The OSG 1400158908 is a thread forming tap designed for blind hole threading in metal workpieces. It cuts no chips — instead, it cold-forms 1/4-20 UNC internal threads by displacing material, producing a stronger thread form with a smooth finish. Built from cobalt high-speed steel and finished with a TiCN coating, this tap handles the heat and abrasion common in production tapping operations. The modified bottoming chamfer (2 to 2.5 chamfered threads) allows threading close to the bottom of a blind hole. Overall length is 2.5 inches with a thread length of 0.594 inches and a shank diameter of 0.255 inches. Part of the OSG HY-PRO NRT Series 14001 line, it is suited for licensed machinists and tool-and-die professionals running right-hand threaded fastener holes.

This tap is rated for use in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The TiCN coating extends tool life in abrasive and higher-hardness materials. Thread limit is H11, which accommodates plated or tight-tolerance thread fits common in precision machined components. The modified bottoming chamfer makes it well suited for blind holes where full thread engagement depth near the hole bottom is required. It does not support coolant-through delivery, so flood or spray coolant applied externally is the standard approach in production environments.

Key Features

• Thread forming (chipless) design produces stronger threads and eliminates chip evacuation concerns in blind holes
• Cobalt HSS construction provides heat resistance for tapping harder alloys and stainless grades
• TiCN coating reduces friction and wear, extending service life across abrasive materials
• Modified bottoming chamfer (2 to 2.5P) enables threading close to the bottom of blind holes
• H11 thread limit supports plated and tight-tolerance fastener fits
• Right-hand, 1/4-20 UNC thread form for standard inch-series fastener applications

Compatibility

Designed for blind hole threading in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Suitable for use in standard tapping chucks and CNC machining center toolholders accepting a 0.255-inch shank diameter with a 0.191-inch square drive.

Installation Notes

Thread forming taps require a pilot hole sized for the forming process — the recommended forming tap drill size for 1/4-20 UNC differs from a standard cut tap drill and should be confirmed against the manufacturer drill chart before use. Secure the tap in a rigid holder with appropriate torque control to prevent overload, especially in harder steels. Apply cutting fluid or tapping compound rated for the workpiece material; flood coolant is acceptable since this tap does not support coolant-through delivery. Always verify spindle speed and feed rate are set to manufacturer recommendations for the specific material being tapped.