Osg 1110200 Straight Flute Tap 1/4-20 Unc Bottoming Hss

Product Description

The OSG 1110200 is a straight flute bottoming tap designed to cut internal threads in blind and through holes where full thread depth close to the bottom of a hole is required. Ground from high-speed steel (HSS) with a bright uncoated finish, it cuts a 1/4-20 UNC right-hand thread and carries a H2 thread limit for controlled tolerance fitment. With four flutes and a bottoming chamfer, this tap is suited for short-run and production threading operations where thread engagement must begin as low as possible in the hole. Overall length is 2.5 inches with a thread length of approximately 0.75 inches.

This tap is used in machine shop, maintenance, and field fabrication environments where 1/4-20 UNC threads are required in ferrous and non-ferrous workpieces. It performs in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The bottoming chamfer style makes it the correct choice when a partially threaded pilot hole has already been started with a taper or plug tap and full thread depth at the bottom of the bore is needed.

Key Features

• Bottoming chamfer for maximum thread depth in blind holes
• High-speed steel construction for durability across ferrous and non-ferrous materials
• H2 thread limit for consistent tolerance control in 1/4-20 UNC applications
• Four-flute design provides chip clearance and stable cutting geometry
• Bright uncoated finish suits general-purpose threading without specialty coatings
• Right-hand thread, standard UNC form - direct replacement for common 1/4-20 bottoming taps

Compatibility

Designed as a standard 1/4-20 UNC bottoming tap compatible with tapping heads, drill presses, CNC machining centers, and hand tap handles sized for the 0.255-inch shank diameter. Suitable for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel applications per the OSG Series 101 specification.

Installation Notes

A licensed machinist or qualified technician should select the correct tap drill size for 1/4-20 UNC before use; consult Machinery's Handbook or standard tap drill charts for proper drill diameter. Always ensure the workpiece is securely fixtured and the tap is properly aligned to avoid tap breakage. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. In blind-hole applications, use a taper tap first to start the thread, then follow with this bottoming tap to extend thread engagement to the bottom of the bore.