Osg 1651000 Straight Flute Tap 10-24 Unc Bottoming Lh Hss

Product Description

The OSG 1651000 is a straight flute bottoming tap designed for cutting left-hand internal threads in a wide range of metals. Built from high-speed steel with a bright, uncoated finish, it produces 10-24 UNC threads with a 2B/3B class of fit. The bottoming chamfer allows threading close to the bottom of a blind hole, making it the right choice when thread engagement must extend deep into the bore. With 4 flutes and an H3 thread limit, this tap is suited for precision tapping operations where dimensional consistency matters. It is sized at 2.375 inches overall length with a 0.875-inch thread length and a shank diameter of 0.194 inches.

This tap is intended for use in machine shop, maintenance, and production environments where left-hand threads are required. Typical applications include tapping blind holes in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The bottoming chamfer style makes it particularly useful as a finishing tap following a taper or plug tap in a blind-hole sequence. It is well suited for use in manual tapping setups or CNC machining centers running left-hand operations.

Key Features

• Left-hand thread direction for reverse-thread applications
• Bottoming chamfer for threading to the base of blind holes
• H3 thread limit for controlled fit in 2B and 3B tolerance applications
• High-speed steel construction suitable for steel, cast iron, and aluminum
• 4-flute design for chip control and thread quality in through and blind holes
• Bright, uncoated finish - no coolant-through requirement

Compatibility

Compatible with materials including aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. Designed as an OEM-style replacement or direct-use tap for any application requiring 10-24 UNC left-hand internal threads.

Installation Notes

This tap is installed and operated by machinists or tool-and-die professionals using a tap wrench, tapping head, or CNC spindle configured for left-hand rotation. Always ensure the correct pilot hole diameter is drilled per UNC tap drill charts before threading. Power down or disengage the spindle before tool changes, and secure the workpiece firmly to prevent movement during tapping. Use cutting fluid appropriate for the workpiece material to extend tool life and improve thread finish.