Osg 1102900 Straight Flute Tap 1/2-20 Unf Bottoming Hss

Product Description

The OSG 1102900 is a straight flute bottoming tap designed for cutting 1/2-20 UNF right-hand internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel with a bright uncoated finish, it carries an H1 thread limit for close-tolerance work. The four-flute straight-flute geometry channels chips up and out of the hole, making it well suited to through-holes and shallow blind holes where chip evacuation is manageable. Overall length is 3-3/8 inches with a thread length of 1-21/32 inches and a shank diameter of 0.367 inches. Bottoming chamfer geometry allows threading to within a few pitches of the bottom of a blind hole.

This tap is used in machine shops, maintenance facilities, and field repair settings where 1/2-20 UNF threaded holes are required. Typical material applications include aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. The bottoming chamfer makes it the finishing tap in a two- or three-tap sequence after a taper or plug tap has started the thread, maximizing thread engagement depth in blind-hole applications.

Key Features

• Bottoming chamfer allows threading to near full depth in blind holes
• Four straight flutes for controlled chip flow in through and shallow blind holes
• High-speed steel construction handles a broad range of ferrous and non-ferrous workpiece materials
• H1 thread limit for tight-tolerance 1/2-20 UNF thread production
• Bright uncoated finish - no coating buildup to affect thread dimensions
• Right-hand thread direction, compatible with standard tapping heads and tap handles

Compatibility

Designed for use in any application requiring a 1/2-20 UNF right-hand internal thread in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, or medium-carbon steel. Part of OSG Series 101.

Installation Notes

This tap is installed and operated by a licensed machinist or qualified maintenance technician using a tap handle, tapping head, or machine spindle set to the appropriate speed for the workpiece material. Secure the workpiece fully before tapping and ensure the tap is properly aligned with the pre-drilled pilot hole to avoid tap breakage. Use cutting fluid appropriate for the workpiece material to extend tap life and improve thread finish. Follow standard shop safety practices and power down or de-energize any machine before changing tooling.