Osg 1662000 Straight Flute Tap 1/2-20 Unf Bottoming Hss Left Hand

Product Description

The OSG 1662000 is a straight flute bottoming tap designed for cutting left-hand internal threads to a 1/2-20 UNF specification. Built from high-speed steel with a bright/uncoated finish, it delivers consistent thread form in a range of ferrous and non-ferrous materials. The bottoming chamfer allows threading to the bottom of blind holes where plug or taper taps cannot reach. With 4 flutes and an H3 thread limit, the 1662000 holds tight tolerances appropriate for a 3B class of fit. Overall length is 3.375 inches with a thread length of 1.153 inches, making it suited to moderate-depth tapping applications in production and maintenance machining environments.

This tap is used in applications that require left-hand threaded blind holes in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces. It is appropriate for manual hand tapping as well as machine tapping setups where a straight flute geometry is preferred for through-chip clearing in shorter thread lengths. The bottoming chamfer makes it the correct choice for finishing a blind hole after an initial pass with a plug or taper tap.

Key Features

• Bottoming chamfer for threading to the base of blind holes
• Left-hand thread direction - 1/2-20 UNF
• 4 straight flutes for stability and consistent chip formation
• H3 thread limit for controlled 3B class-of-fit tolerances
• High-speed steel construction with bright/uncoated finish
• Compatible material range includes aluminum, cast iron, and carbon steels

Compatibility

Designed for tapping left-hand 1/2-20 UNF threads in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Part of the OSG Series 101L straight flute tap line.

Installation Notes

Installation is performed by a machinist or maintenance technician using a tap wrench or tapping head configured for left-hand rotation. Power down and secure the workpiece before starting. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. For blind holes, use a plug or taper tap first to establish the thread, then finish with this bottoming tap - forcing a bottoming tap into an unprepared hole risks tap breakage.