Osg 2866408 Thread Forming Tap 5/16-24 Unf Bottoming Ticn

Product Description

The OSG 2866408 is a thread forming tap designed for blind hole threading in ferrous and non-ferrous metals. Manufactured from high-speed steel with a TiCN coating, this tap forms internal threads through material displacement rather than cutting, which produces stronger threads and eliminates chip management concerns. It is sized for 5/16-24 UNF threads with a 2B class of fit and features a bottoming chamfer of 1.5 to 2 threads, allowing threading close to the bottom of a blind hole. Overall length is 2.719 inches with a 0.665-inch thread length and a shank diameter of 0.318 inches. Machinists, tool-and-die makers, and maintenance technicians handling precision threading work install this tap in standard tapping equipment.

This tap is suited for blind hole threading applications in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel. The bottoming chamfer design makes it the correct choice when full-depth thread engagement is required near the base of a non-through hole. It carries the OSG HY-PRO NRT trade designation and is part of OSG Series 285. Right-hand thread direction applies. The TiCN coating reduces galling and extends tool life particularly in aluminum and steel applications common in automotive, general machining, and maintenance repair environments.

Key Features

• Thread forming (chipless) design displaces material to form stronger threads and eliminates chip extraction in blind holes
• TiCN coating improves wear resistance and reduces friction during tapping in aluminum and steel
• Bottoming chamfer (1.5 to 2 threads) allows threading to the full depth of blind holes
• High-speed steel construction provides toughness and heat resistance for general shop use
• 5/16-24 UNF 2B class of fit for standard unified fine-thread applications
• Right-hand thread direction compatible with standard tapping equipment and CNC machining centers

Compatibility

Rated for use in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel. Material application codes P and N per OSG classification. Designed for blind hole threading where a bottoming chamfer is required to achieve full thread depth.

Installation Notes

Thread forming taps require the correct tap drill size for the material and desired thread engagement percentage — consult a thread forming tap drill chart before drilling the pilot hole, as the required drill diameter is larger than for a cutting tap of the same thread size. Use a tapping fluid or cutting oil appropriate for the workpiece material, particularly for steel applications. Ensure the tap is held square to the workpiece to prevent thread distortion or tool breakage. Power down or disengage the spindle before manually backing the tap out of a blind hole.