Osg 2866200 Thread Forming Tap 5/16-18 Unc Bottoming Hss

Product Description

The OSG 2866200 is a thread forming tap designed for creating internal threads without cutting, using cold-forming action to displace material rather than remove chips. Sized for 5/16-18 UNC threads with a 2B class of fit, this bottoming tap features a 1.5 to 2 thread chamfer that allows threading close to the bottom of a blind hole. Manufactured from high-speed steel with a bright finish, it is built for production and maintenance threading operations where clean, strong threads are required. A right-hand thread direction and 18 threads per inch conform to standard UNC specifications.

This tap is rated for use in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel. Its bottoming chamfer design makes it well suited for blind hole threading applications where full thread depth near the hole bottom is needed. The 5/16-18 UNC size is common in light structural, mechanical, and general fabrication work across manufacturing, maintenance, and repair environments. It is typically used by machinists, tool and die technicians, and maintenance mechanics on manual or CNC tapping equipment.

Key Features

• Bottoming chamfer with 1.5 to 2 thread lead for threading close to blind hole bottoms
• 5/16-18 UNC thread form with 2B class of fit for standard tolerance internal threads
• High-speed steel construction for use across a range of ferrous and non-ferrous materials
• Right-hand thread direction compatible with standard tapping equipment
• Bright finish with no coating for straightforward inspection and regrinding
• No coolant-through requirement, simplifying setup on manual or light CNC equipment

Compatibility

Designed for blind hole threading in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel workpieces requiring 5/16-18 UNC internal threads at a 2B class of fit.

Installation Notes

Thread forming taps require proper lubrication matched to the workpiece material to prevent galling and premature wear. Ensure the tap is aligned perpendicular to the workpiece surface before starting the thread form. Use a tap wrench, tapping head, or CNC tapping cycle with appropriate feed rate for the material. Never force a bottoming tap beyond its rated tapping depth, as doing so risks tap breakage in blind holes.