Osg 1761801 Spiral Flute Tap 3/8-16 Unc Modified Bottoming

Product Description

The OSG 1761801 is a spiral flute tap designed for cutting 3/8-16 UNC internal threads in a range of ferrous materials. Built from vanadium high-speed steel and finished with a steam oxide coating, it is engineered for durability and chip evacuation in through-hole and blind-hole applications. The spiral flute geometry, running at a 45-degree helix angle, pulls chips up and out of the hole, making it well suited to tougher materials like stainless steel where chip packing is a concern. With a modified bottoming chamfer, this tap threads close to the bottom of a blind hole while still entering cleanly. It carries a 2B class of fit and an H7 thread limit, targeting standard commercial tolerance threads.

This tap is intended for use in machining, fabrication, and maintenance environments where 3/8-16 UNC threads are required in stainless steel, high-carbon steel, medium-carbon steel, and low-carbon steel. The modified bottoming chamfer makes it appropriate for blind holes where full thread depth near the bottom is needed. It is part of OSG Series 303 and is sized for use in standard tap holders and CNC or manual tapping setups. Licensed machinists, tool-and-die makers, and maintenance mechanics are the primary users.

Key Features

• 45-degree right-hand spiral flute geometry evacuates chips upward, reducing packing in blind holes
• Modified bottoming chamfer allows threading close to the bottom of a blind hole
• Vanadium high-speed steel construction provides increased wear resistance over standard HSS
• Steam oxide coating reduces friction and provides light corrosion resistance during storage and use
• H7 thread limit and 2B class of fit meet standard commercial tolerance requirements
• No coolant-through design; suitable for use with external cutting fluid application

Compatibility

Rated for use in stainless steel, high-carbon steel, medium-carbon steel, and low-carbon steel. Designed as an OEM-style replacement or direct-use tap for any application requiring 3/8-16 UNC threads at 2B class of fit.

Installation Notes

This tap should be installed by a qualified machinist or maintenance technician familiar with tapping operations and appropriate cutting speeds for the workpiece material. Always apply a suitable cutting fluid for the material being tapped, particularly when working with stainless steel. Secure the workpiece firmly before tapping and ensure the tap is aligned perpendicular to the drilled hole to avoid tap breakage. Follow shop safety procedures and OSHA standards for machine tool operation.