Osg 1012500 Straight Flute Tap 4-48 Unf 3 Flutes Plug

Product Description

The OSG 1012500 is a straight flute tap designed to cut 4-48 UNF internal threads in a range of ferrous and non-ferrous materials. Built from high-speed steel with a bright/uncoated finish, it features 3 flutes and a plug chamfer that helps guide the tap into the workpiece while distributing the cutting load across several teeth. The H2 thread limit provides controlled oversize tolerance for reliable thread fit in 2B class-of-fit applications. Overall length is 1.875 inches with a thread length of 0.5625 inches (9/16 inches), making it suited for shallow-to-moderate depth tapping operations where chip evacuation is manageable.

This tap is intended for hand or machine tapping in production and maintenance machining environments. It is well suited for threading aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The straight flute design works best in through holes or short blind holes where chips can fall away from the cutting zone. It is a common choice for toolmakers, maintenance machinists, and production shops working with fine-thread fastener sizes in the No. 4 diameter range.

Key Features

• 4-48 UNF thread form for fine-pitch fastener applications
• Plug chamfer starts threads easily and distributes cutting load
• 3 straight flutes suited for through holes and short blind holes
• H2 thread limit for 2B class-of-fit compliance
• High-speed steel construction handles a broad range of workpiece materials
• Right-hand thread direction; no coolant-through requirement

Compatibility

Designed for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces requiring 4-48 UNF internal threads to a 2B class of fit. Part of the OSG Series 102 tap line.

Installation Notes

This tap is installed by machinists and maintenance technicians using a tap wrench, tapping head, or CNC machine spindle set to the correct RPM and feed for the workpiece material. Always ensure the workpiece is securely fixtured and the tap is properly aligned with the drilled pilot hole before threading begins. Back the tap off periodically to break chips and prevent binding in the flutes. Do not force a tap that has stalled, as high-speed steel is brittle under torsional overload.