Osg 1405008208 Thread Forming Tap 1/4-28 Unf Modified Bottoming

Product Description

The OSG 1405008208 is a thread forming tap in the EXOTAP VP-NRT series, designed for cold-forming internal threads without cutting or producing chips. Built from powdered metal high-speed steel (PM-HSS) with a TiCN coating, this tap produces a 1/4-28 UNF right-hand thread in blind hole applications. The modified bottoming chamfer, with 2 to 2.5 chamfered threads, allows threading close to the bottom of a blind hole. At 2.5 inches overall length and a thread length of 0.5945 inches, it fits standard machine tool setups. Machinists and toolroom technicians use this tap where thread strength and surface finish are critical.

This tap is suited for production and maintenance machining in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. It is rated for blind hole threading, making it appropriate for engine components, tooling fixtures, and precision assemblies where chip evacuation is a concern. The H6 thread limit and Class 2B fit designation make it compatible with standard fastener clearances in both job shop and production environments. The TiCN coating extends tool life under demanding cutting conditions.

Key Features

• Cold-forming action eliminates chips, reducing the risk of chip packing in blind holes
• Powdered metal HSS substrate provides consistent grain structure and improved wear resistance over conventional HSS
• TiCN coating increases surface hardness and reduces friction during tapping
• Modified bottoming chamfer allows threading to within 2 to 2.5 thread pitches of hole bottom
• H6 thread limit and Class 2B fit meet standard UNF tolerance requirements
• Right-hand thread direction compatible with standard machine tapping heads and CNC tapping cycles

Compatibility

Designed for blind hole thread forming in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Intended for use in standard machine tool holders, tapping heads, and CNC machining centers capable of 1/4-inch tooling. Material application codes P, M, and N apply per the supplier specification.

Installation Notes

Thread forming taps require a properly sized forming tap drill hole, which is larger than a cutting tap drill size for the same thread — consult a forming tap drill chart for 1/4-28 UNF before setup. Use a tapping fluid or cutting oil rated for the workpiece material; dry tapping is not recommended with PM-HSS tooling. Ensure the spindle is set to the correct RPM and feed rate for the material and tap diameter before engaging the hole. Inspect the shank and square drive for wear before each use to prevent slippage in the holder.