Osg 1662500 Straight Flute Tap 5/8-11 Unc Left Hand Hss

Product Description

The OSG 1662500 is a straight flute tap designed to cut internal left-hand threads in a range of metals. Built from high-speed steel with a bright, uncoated finish, it produces 5/8-11 UNC threads to a 3B class of fit with an H3 thread limit. The plug chamfer — typically 3 to 5 threads — makes this tap best suited for through-hole tapping applications where chip flow is not a primary constraint. With a 1-13/16-inch thread length and a 3-13/16-inch overall length, it fits standard tap handles and machine setups used by machinists and maintenance technicians in fabrication and industrial service environments.

This tap is intended for use in through-hole applications across a broad range of ferrous and non-ferrous workpiece materials. It cuts left-hand threads, making it the correct choice for applications where reverse-torque loading or counter-clockwise shaft rotation would cause a standard right-hand thread to loosen over time. Typical use cases include spindle components, turnbuckle hardware, and mechanical assemblies requiring left-hand fastening. The 5/8-11 UNC thread form is a common coarse-pitch size used throughout industrial and structural applications.

Key Features

• Left-hand thread direction for counter-clockwise fastening applications
• 5/8-11 UNC thread form, 3B class of fit, H3 thread limit for controlled tolerance
• Plug chamfer (3-5 lead threads) optimized for through-hole tapping
• High-speed steel construction — suitable for aluminum, cast iron, and low-, medium-, and high-carbon steels
• Bright, uncoated finish — no coating variables to account for during setup
• 4 straight flutes with a 1-13/16-inch thread length and no coolant-through requirement

Compatibility

Compatible workpiece materials include aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. This tap is part of the OSG Series 101L and is designed for standard through-hole tapping in manual tap handles or machine tapping setups accepting the 0.48-inch shank diameter.

Installation Notes

This tap produces left-hand threads — confirm thread direction requirements before use, as it will not produce a usable thread in a right-hand-tapped hole. Secure the workpiece fully before starting; misalignment at entry will damage the tap and the hole. Use a tapping fluid or cutting oil appropriate to the workpiece material to extend tool life and improve thread quality. Follow your shop safety procedures for rotating or hand-driven cutting tools.