Osg 1142300 Straight Flute Tap 7/16-20 Unf Bottoming Hss

Product Description

The OSG 1142300 is a straight flute bottoming tap designed for threading 7/16-20 UNF holes in a wide range of ferrous and non-ferrous materials. It is ground from high-speed steel (HSS) with a bright, uncoated finish and carries a 4-flute, right-hand thread configuration. The bottoming chamfer allows threading to the bottom of blind holes where plug or taper taps cannot reach. With an overall length of 3-5/32 inches and a thread length of 1-7/16 inches, this tap suits standard machine or hand tapping operations. Thread limit is H5, indicating a Class 3B tolerance fit appropriate for precision threaded assemblies.

This tap is suited for production and maintenance tapping in machine shops, manufacturing facilities, and field maintenance environments. It is an effective choice when blind-hole threading of 7/16-20 UNF fastener holes is required. Compatible material applications include aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel, making it a versatile option across general machining and fabrication work. It is typically run in drill presses, CNC machining centers, or tapping machines, as well as with manual tap wrenches for hand operations.

Key Features

• Bottoming chamfer allows threading to the bottom of blind holes
• 4 straight flutes for chip clearance in through and blind-hole applications
• High-speed steel construction provides durability across steel and aluminum workpieces
• H5 thread limit for precise Class 3B tolerance fits
• Right-hand thread direction, 7/16-20 UNF specification
• Bright/uncoated finish suitable for use with standard cutting fluids

Compatibility

Designed for tapping 7/16-20 UNF threads in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. Part of OSG Series 101.

Installation Notes

Ensure the workpiece is securely fixtured before tapping to prevent movement and thread misalignment. Always use an appropriate cutting fluid or tapping compound matched to the workpiece material. For blind holes, clear chips frequently to prevent tap breakage, particularly with a bottoming tap that has minimal chip-ejection chamfer. Follow safe machine operation procedures and verify spindle speed and feed rate are appropriate for the tap size and material before engaging the cut.