Osg 1145800 Straight Flute Tap 7/8-14 Unf Plug Hss

Product Description

The OSG 1145800 is a straight flute tap designed to cut internal 7/8-14 UNF right-hand threads in a range of ferrous and non-ferrous materials. Built from high-speed steel with a bright, uncoated finish, this plug-chamfer tap is suited for through-hole and moderate-depth blind-hole applications where chip evacuation is managed manually or with cutting fluid. It carries a 2B class of fit and an H6 thread limit, producing threads within standard tolerance for general mechanical assemblies. Overall length is 4-11/16 inches with a thread length of 2-7/32 inches, making it compatible with standard tap holders and machine spindles used in production and maintenance environments.

This tap is intended for machinists, tool-and-die makers, and maintenance technicians working in job shops, manufacturing facilities, and MRO settings. It is well suited for tapping aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces. The plug chamfer - typically 3 to 5 threads of lead - makes it a practical choice for starting threads in through holes or as a follow-up tap after a taper tap in blind holes. It is part of OSG Series 101 and is sold as a single unit.

Key Features

• 7/8-14 UNF thread form with right-hand cutting direction
• 4 straight flutes for use in through holes and shallow blind holes
• Plug chamfer provides controlled thread lead-in and balanced cutting load
• H6 thread limit and 2B class of fit for standard tolerance assemblies
• High-speed steel construction with bright, uncoated finish - compatible with cutting oils and water-soluble coolants
• No coolant-through feature; external flood or brush lubrication required

Compatibility

Designed as an OEM-style replacement or direct-use tap for applications requiring a 7/8-14 UNF, 2B class of fit, H6 thread limit in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Part of OSG Series 101.

Installation Notes

This tap is installed by qualified machinists using a standard tap wrench, tapping head, or CNC rigid-tap spindle sized for the 0.697-inch shank diameter. Always secure the workpiece and align the tap perpendicular to the hole before applying cutting pressure. Use an appropriate cutting fluid for the workpiece material to extend tool life and maintain thread quality. Reverse the tap periodically when hand-tapping to break chips and prevent binding.