Osg 1400125905 Thread Forming Tap 1/4-20 Unc Bottoming

Product Description

The OSG 1400125905 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal threads without cutting. Unlike cutting taps, this tool displaces material to create strong, work-hardened threads with no chips to clear. It is configured with a bottoming chamfer of 1 to 1.5 threads, making it suited for threading close to the bottom of a blind hole. Built from cobalt high-speed steel and coated with TiN, it offers increased hardness and heat resistance compared to standard HSS taps. Overall length is 2.5 inches, with a thread length of 0.594 inches and a tapping depth of 0.933 inches. Shank diameter is 0.255 inches with a square size of 0.191 inches.

This tap is intended for blind hole threading applications across a range of ferrous and non-ferrous workpiece materials. Rated for use in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The H8 thread limit designates a tighter tolerance range appropriate for close-fit thread assemblies. The right-hand, 1/4-20 UNC configuration makes it a standard choice for machine shops, maintenance operations, and production environments where UNC fastener threads are required in ductile materials.

Key Features

• Thread forming design displaces rather than cuts material, producing chip-free threads with improved thread strength
• Bottoming chamfer (1 to 1.5 threads) allows threading to within a few pitches of the bottom of a blind hole
• Cobalt HSS construction provides elevated hardness and thermal resistance for tougher alloys and stainless steel
• TiN coating reduces friction and extends tool life across high-cycle applications
• H8 thread limit for precise tolerance control in close-fit assemblies
• Right-hand, 1/4-20 UNC thread form compatible with standard UNC fastener specifications

Compatibility

Designed for blind hole threading in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Material application codes P and N indicate suitability for steel and non-ferrous material groups per standard tooling classification.

Installation Notes

Thread forming taps require a specific forming drill size — use the recommended forming tap drill chart for 1/4-20 UNC to select the correct hole diameter before tapping; the hole must be larger than a standard cutting tap drill. Secure the workpiece and use a calibrated tap handle or CNC rigid tapping cycle with appropriate feed rate. Apply a suitable tapping fluid or cutting oil rated for the workpiece material. Do not reverse the tap before it has completed the forming stroke, and inspect the tap for wear or chipping before each use on hardened steels.