Osg 1011105 Straight Flute Tap 2-56 Unc Bottoming Tin Hss

Product Description

The OSG 1011105 is a straight flute bottoming tap designed to cut internal threads in blind and through holes requiring full thread depth close to the bottom. Built from high-speed steel with a titanium nitride (TiN) coating, it produces clean, accurate threads in a 2-56 UNC configuration at 56 threads per inch. The bottoming chamfer allows threading to within a few threads of the bottom of a blind hole. At 1.75 inches overall length with a 0.437 inch thread length, this compact tap fits standard tap holders and T-handle wrenches used in machining and assembly work. Class of fit is 2B with an H2 thread limit for consistent dimensional results.

This tap is suited for small-fastener tapping operations in light manufacturing, precision machining, electronics assembly, and maintenance work. The 2-56 UNC thread size is common in miniature hardware, instrument panels, circuit board standoffs, and small enclosures. Material applications include aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. It is part of OSG Series 102 and is intended for use where a bottoming chamfer is required to maximize thread engagement depth in a confined hole.

Key Features

• Bottoming chamfer allows full thread depth at the bottom of blind holes
• TiN coating reduces friction and wear, extending tool life in steel and aluminum
• High-speed steel construction handles a broad range of workpiece materials
• 3 straight flutes for chip clearance in through and shallow blind holes
• 2B class of fit with H2 thread limit for standard tolerance internal threads
• Right-hand thread direction, no coolant-through requirement

Compatibility

Designed for tapping 2-56 UNC internal threads in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces. Compatible with standard tap holders, T-handle wrenches, and machine tap adapters accepting a 0.141 inch shank diameter.

Installation Notes

This tap is installed and used by machinists, toolmakers, and assembly technicians. Always drill the correct tap drill size for a 2-56 UNC thread before tapping, and ensure the workpiece is secured before starting. Apply cutting fluid appropriate for the workpiece material to reduce heat and improve thread finish. Do not force the tap if resistance increases sharply, as breakage of small-diameter taps is common when over-torqued.