Irwin 1534 Straight Flute Tap 3/8-16 Unc 4 Flute Bottoming

Product Description

The IRWIN 1534 is a straight flute tap designed for cutting internal threads in through-holes and blind holes where a bottoming chamfer is required. Manufactured from carbon steel, it cuts 3/8-16 UNC threads with a 2B class of fit — the standard tolerance for most general-purpose fastener applications. With 4 flutes and a bottoming chamfer, it is built to thread close to the bottom of a blind hole where a plug or taper tap cannot reach. The overall length is 3 inches, with a thread length of 1.5 inches. Machinists, maintenance mechanics, and trade professionals use this tap for tapping operations in ferrous and softer non-ferrous materials.

This tap is suited for production and repair tapping in machine shops, manufacturing facilities, and maintenance environments. Its 3/8-16 UNC thread form is one of the most common unified coarse thread sizes found in structural fastening, equipment assembly, and field repair work. The straight flute design makes it well-suited for through-hole tapping and short blind-hole applications where chip clearance is manageable. The 2B class of fit produces threads that mate with standard 2A external fasteners without requiring special tolerancing.

Key Features

• Bottoming chamfer allows threading to within 1-2 threads of the bottom of a blind hole
• 4-flute straight flute design provides rigidity and clean thread form in ferrous materials
• 3/8-16 UNC thread form — one of the most common coarse-thread sizes in trade applications
• 2B class of fit for standard tolerance thread mating with 2A fasteners
• Carbon steel construction suitable for general-purpose tapping operations
• Right-hand thread direction for standard tapping with conventional tooling

Compatibility

Designed as an OEM-style replacement or standard production tap for use in 3/8-16 UNC tapping applications in machine tools, drill presses, and hand tapping setups.

Installation Notes

This tap is installed and operated by machinists or maintenance mechanics using a tap wrench, tapping fixture, or machine spindle. Always use appropriate cutting fluid for the workpiece material to extend tap life and reduce the risk of breakage. Ensure the tap is properly aligned perpendicular to the workpiece before beginning the cut. Do not force the tap — back off periodically to break chips and clear the flutes, especially in deeper blind holes.