Osg 1601807 Straight Flute Tap 3/8-24 Unf Bottoming Hss

Product Description

The OSG 1601807 is a straight flute bottoming tap designed for cutting 3/8-24 UNF internal threads in machined components. With 4 flutes and an H3 thread limit, it produces accurate 3B class of fit threads suited to close-tolerance fastener applications. The tap is manufactured from high-speed steel (HSS) and carries a nitride/oxide combination coating that reduces friction and extends tool life in production environments. The bottoming chamfer allows threading close to the bottom of blind holes. Overall length is 2-15/16 inches with a thread length of 1-1/4 inches. Licensed machinists, tool and die makers, and maintenance technicians are the primary users.

The OSG 1601807 is suited for tapping aluminum and cast iron workpieces in both production and job-shop settings. Its straight flute geometry works well in these short-chip materials where flute evacuation is straightforward. The bottoming chamfer makes it the correct choice when thread engagement must extend to the floor of a blind hole, a common requirement in fixture plates, brackets, and machined housings. It is not designed for through-hole or interrupted-thread applications where a spiral flute tap would be more appropriate.

Key Features

• 3/8-24 UNF thread form with 3B class of fit for close-tolerance internal threads
• Bottoming chamfer allows threading to the bottom of blind holes
• H3 thread limit for consistent fit across production runs
• 4-flute straight flute design optimized for aluminum and cast iron
• High-speed steel construction with nitride/oxide coating for reduced friction and improved tool life
• Right-hand thread direction, no coolant-through requirement

Compatibility

Designed for tapping aluminum and cast iron workpieces requiring 3/8-24 UNF internal threads. Compatible with standard tap holders and chucks accepting a 0.381-inch shank diameter with a 0.286-inch square drive.

Installation Notes

Tapping should be performed by a qualified machinist following standard threading procedures. Secure the workpiece and ensure the tap is aligned perpendicular to the drilled hole before engagement. Apply an appropriate cutting fluid for the workpiece material - sulfurized oil for cast iron and a light cutting fluid or kerosene-based lubricant for aluminum. Inspect the tap for wear or chipping before each use and replace if thread form or coating shows degradation.