Osg 1591300 Straight Flute Tap 3/8-16 Unc Plug Hss

Product Description

The OSG 1591300 is a straight flute plug tap designed for cutting 3/8-16 UNC internal threads in a range of ferrous and non-ferrous materials. Built from high-speed steel with a bright, uncoated finish, this tap delivers consistent thread quality in production and repair applications. It features 4 flutes, a plug chamfer for progressive thread engagement, and an H11 thread limit classification indicating a controlled oversize of 0.005 inches for proper fit with standard tolerance nuts and threaded inserts. Overall length is 2-15/16 inches with a thread length of 1-1/4 inches.

This tap is suited for hand tapping and machine tapping operations in job shops, maintenance facilities, and manufacturing environments. The plug chamfer makes it a versatile choice for through-holes and deep blind holes where partial thread engagement on entry is acceptable. The Series 101H designation indicates it is an OSG standard production tap intended for general-purpose threading work where consistent H-limit tolerance is required across volume runs or single-piece repairs.

Key Features

• 3/8-16 UNC thread form, right-hand thread direction
• 4 straight flutes with plug chamfer for gradual thread engagement
• High-speed steel construction for durability across ferrous and non-ferrous workpieces
• H11 thread limit with 0.005 inch oversize for controlled fit
• Bright, uncoated finish suitable for use with cutting fluid across a wide range of materials
• No coolant-through requirement, compatible with standard flood or brush-applied cutting lubricants

Compatibility

Rated for use in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. Designed as a direct-fit replacement or standard production tap for 3/8-16 UNC threaded hole applications following ASME B1.1 Unified National Coarse thread standards.

Installation Notes

This tap should be installed and operated by a machinist or maintenance technician familiar with thread-cutting procedures. Always secure the workpiece and use appropriate cutting fluid for the material being tapped to prevent galling and extend tool life. When tapping by machine, verify spindle alignment and use a tapping head where applicable to prevent tap breakage. Power down and de-energize any machine tool before changing tooling per standard lockout/tagout procedures.