Osg 1140800 Straight Flute Tap 5/16-18 Unc Bottoming Hss

Product Description

The OSG 1140800 is a straight flute bottoming tap designed for producing fully threaded blind holes in a range of ferrous and non-ferrous materials. Ground to a 5/16-18 UNC thread form with a 2B class of fit and H5 thread limit, it delivers consistent, accurate threads in production and maintenance applications. Constructed from high-speed steel with a bright/uncoated finish, the 4-flute design provides strength and chip control during hand or machine tapping operations. Overall length is 2-23/32 inches with a thread length of 1-1/8 inches, making it well suited for through-hole and shallow blind-hole work where maximum thread depth is required.

This tap is intended for tapping operations in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The bottoming chamfer - typically 1 to 2 threads of lead - allows threading to the bottom of blind holes where spiral or plug taps cannot reach full thread depth. It fits standard tap handles and CNC tapping attachments and is a common choice for machine shops, maintenance technicians, and fabrication environments requiring 5/16-18 UNC threads.

Key Features

• 5/16-18 UNC thread form with 2B class of fit for standard tolerance threaded holes
• Bottoming chamfer for threading to the base of blind holes
• H5 thread limit for controlled oversize tolerance
• 4 straight flutes in high-speed steel construction for durability across a broad material range
• Bright/uncoated finish - no coating to interfere with close-tolerance thread dimensions
• Right-hand thread direction; no coolant-through requirement

Compatibility

Designed as an OEM-style replacement or direct-use straight flute tap for standard 5/16-18 UNC tapping applications across production and maintenance environments. Compatible with materials including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel per OSG Series 101 specifications.

Installation Notes

Tapping operations should be performed by a qualified machinist or maintenance technician using appropriate tapping fluid for the workpiece material. Ensure the workpiece is securely clamped and the tap is properly aligned to the pre-drilled pilot hole before engagement. Power down any machine tool and confirm the spindle is locked before changing taps. Follow applicable shop safety practices and machine tool manufacturer guidelines when using power tapping equipment.