Osg 1986400 Spiral Flute Tap M8x1.25 Bottoming 6H Hss

Product Description

The OSG 1986400 is a spiral flute bottoming tap designed for threading M8x1.25 metric coarse holes in a wide range of ferrous and non-ferrous materials. Built from high-speed steel with a bright uncoated finish, it features a 3-flute spiral design with a 50-degree helix angle that efficiently evacuates chips up and out of the hole during tapping. The bottoming chamfer allows threading close to the bottom of blind holes where plug or taper taps cannot reach. With an overall length of 2-23/32 inches and a D5 thread limit, this tap is suited for production and maintenance tapping operations performed by machinists and tool-and-die professionals.

This tap is intended for use in blind-hole applications across a broad spectrum of materials including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. It carries a 6H class of fit, making it appropriate for standard metric fastener applications in both production shop and field repair environments. The right-hand thread direction and right-hand flute direction suit conventional tapping setups on CNC machining centers, drill presses, and hand tapping fixtures.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• 50-degree helix angle promotes upward chip evacuation in blind-hole tapping
• High-speed steel construction provides durability across a broad material range
• 6H class of fit meets standard metric thread tolerance requirements
• D5 thread limit for consistent sizing across production runs
• Bright uncoated finish suitable for use with cutting fluids on most common metals

Compatibility

Designed for M8x1.25 metric coarse blind-hole tapping in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces.

Installation Notes

This tap is installed by machinists using a tap wrench, tapping head, or CNC rigid tapping cycle. Always use an appropriate cutting fluid matched to the workpiece material to extend tool life and improve thread finish. Secure the workpiece firmly before tapping and ensure the tap is started square to the hole axis to avoid tap breakage. Inspect the tap for wear or chipping before each use, as a damaged tap can damage the workpiece thread.