Osg 1986401 M8x1.25 Spiral Flute Bottoming Tap 6H Hss

Product Description

The OSG 1986401 is a spiral flute bottoming tap designed for cutting M8x1.25 metric coarse internal threads to a 6H class of fit. Manufactured from high-speed steel with a steam oxide coating, it features three right-hand flutes with a 50-degree helix angle that efficiently evacuate chips upward out of the hole during tapping. The bottoming chamfer allows threading to the very bottom of blind holes. With an overall length of 2-23/32 inches and a thread length of 18 mm, this tap is suited for production and maintenance applications where accurate metric threading is required.

This tap is intended for use in machining and metalworking operations involving blind-hole threading. The 50-degree spiral flute geometry and steam oxide surface finish make it well suited for cutting threads in a range of ferrous and non-ferrous materials. It is commonly used by machinists, toolmakers, and maintenance technicians on manual mills, drill presses, and CNC machining centers where controlled chip flow out of the hole is critical.

Key Features

• M8x1.25 metric coarse thread profile with 6H class of fit for standard tolerance threading
• Bottoming chamfer for threading to the bottom of blind holes
• 50-degree right-hand spiral flute geometry promotes upward chip evacuation
• High-speed steel construction provides durability across a range of workpiece materials
• Steam oxide coating reduces friction and helps resist corrosion during use
• No coolant-through requirement simplifies setup on standard equipment

Compatibility

Rated for use in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. Designed as a standard M8x1.25 bottoming tap suitable for use with compatible tap holders and tapping attachments accepting a round shank with square drive.

Installation Notes

This tap is installed and operated by qualified machinists or maintenance technicians. Before tapping, verify the correct drill size for an M8x1.25 thread and ensure the workpiece is securely fixtured. Use appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. When using a tap wrench or tapping head, apply steady, even pressure and back off periodically to break chips and prevent tap breakage in blind holes.