Osg 2985605 Spiral Flute Tap 1/4-20 Unc Bottoming Tin Hss

Product Description

The OSG 2985605 is a spiral flute tap designed for cutting 1/4-20 UNC internal threads in a bottoming configuration. It features a 50-degree helix angle and three right-hand spiral flutes that evacuate chips back through the flute toward the shank, making it well-suited for blind-hole threading applications. The tap is manufactured from high-speed steel and finished with a titanium nitride (TiN) coating to improve wear resistance and reduce friction during cutting. At 2.5 inches overall length with a 2B class of fit, it delivers accurate, production-ready threads. Machinists, tool and die technicians, and maintenance mechanics install this tap by hand or machine in metalworking operations.

This tap is rated for use in aluminum and carbon steel. The bottoming chamfer style allows threading close to the bottom of a blind hole, making it appropriate for applications where full thread depth is required near a hole bottom. It is commonly used in CNC machining centers, manual lathes, and drill press setups where controlled tapping cycles are available. The right-hand thread direction and right-hand flute direction are standard for conventional tapping operations.

Key Features

• Bottoming chamfer allows threading to within a few threads of a blind hole bottom
• 50-degree helix angle promotes upward chip evacuation in blind-hole applications
• TiN coating improves wear resistance and extends tool life in steel and aluminum
• High-speed steel construction withstands elevated cutting temperatures
• 2B class of fit produces standard tolerance threads for general fastener assembly
• Three flutes provide a balance of strength and chip clearance for the 1/4-20 thread size

Compatibility

Rated for threading aluminum and carbon steel workpieces. Designed as an OEM-style replacement or standard-stock spiral flute tap for any tapping setup that accepts a straight-shank tap with a 0.255-inch shank diameter and standard square drive.

Installation Notes

This tap should be installed by a qualified machinist or tooling technician familiar with tapping feeds, speeds, and cutting fluid requirements for the workpiece material. Ensure the spindle or tapping head is powered down and fully stopped before loading or changing the tap. Use an appropriate cutting fluid or tapping compound for the material being threaded; dry tapping is not recommended for steel. Verify tap alignment with the drilled hole axis before applying cutting torque to prevent tap breakage.