Osg 1170100 Straight Flute Tap 1/4-20 Unc Hss

Product Description

The OSG 1170100 is a straight flute tap designed for cutting internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel with a bright, uncoated finish, it cuts a 1/4-20 UNC right-hand thread to a 3B class of fit with an H3 thread limit. The plug chamfer - typically 3 to 5 threads - allows progressive thread engagement, making this tap well suited for through-hole applications. Overall length is 2.5 inches, with a thread length of approximately 1 inch and a shank diameter of 0.255 inches. Licensed machinists, tool and die makers, maintenance technicians, and general fabricators rely on this tap for production and repair threading work.

This tap is intended for tapping operations in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The three-flute straight flute design provides chip clearance and cutting stability in shorter-chipping materials. It is suited for both manual tapping with a tap wrench and machine tapping on drill presses, mills, and CNC machining centers running at appropriate speeds and feeds for the material. It carries an H3 thread limit, placing it in a slightly oversized tolerance range that accommodates light plating or coating on the finished part where applicable.

Key Features

• 1/4-20 UNC right-hand thread, 3B class of fit with H3 thread limit for consistent, in-tolerance threads
• Plug chamfer (approximately 3 to 5 lead threads) for progressive engagement in through-hole applications
• Three straight flutes for controlled chip evacuation in short-chipping materials
• High-speed steel construction for durability across a broad range of material hardnesses
• Bright, uncoated finish - no coating buildup to affect thread tolerance
• Coolant-through: No - suitable for conventional flooded or manual lubrication setups

Compatibility

Rated for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Designated under OSG Series 103.

Installation Notes

Thread cutting should only be performed with the workpiece securely fixtured and the spindle or tap wrench properly aligned to the pilot hole center. Always apply a cutting fluid or tapping compound appropriate for the workpiece material before and during the tapping operation. When machine tapping, set spindle speed according to the material machinability rating and tap manufacturer recommendations for 1/4-20 HSS taps. Inspect the tap for chipping or wear before each use - a damaged tap can seize in the hole or produce out-of-tolerance threads.