Osg 1971402 M8x1.25 Straight Flute Tap Bottoming Hss

Product Description

The OSG 1971402 is a straight flute bottoming tap designed for threading M8x1.25 metric coarse holes in a wide range of ferrous and non-ferrous metals. Built from high-speed steel, it produces right-hand internal threads to a 6H class of fit with a D5 thread limit, making it suitable for applications that require tight dimensional control. The bottoming chamfer - typically 1 to 2 threads - allows threading to the bottom of a blind hole where taper or plug taps cannot finish the job. With 4 flutes and a 1-1/8 inch thread length, it provides stable cutting action and adequate chip clearance for the materials it is rated for. Overall length is 2-23/32 inches. This tap is intended for use in machine or hand tapping operations by machinists, maintenance technicians, and tool-room professionals.

The OSG 1971402 is suited for production and maintenance tapping in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. It is a strong fit for blind-hole threading operations in manufacturing, fabrication shops, and industrial maintenance environments where a bottoming chamfer is required to achieve full thread depth. The 6H class of fit is the standard tolerance for general-purpose metric fastener threads, making this tap compatible with standard M8x1.25 bolts and screws.

Key Features

• Bottoming chamfer (1-2 thread lead) enables full threading to the bottom of blind holes
• M8x1.25 metric coarse thread form to 6H class of fit with D5 thread limit
• High-speed steel construction provides durability across ferrous and non-ferrous workpieces
• 4 straight flutes deliver stable cutting and chip clearance in through and blind-hole applications
• Right-hand thread direction for standard machine and hand tapping setups
• 1-1/8 inch thread length and 2-23/32 inch overall length suit standard toolholding systems

Compatibility

Rated for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Produces M8x1.25 metric coarse internal threads compatible with standard M8x1.25 fasteners per ISO metric thread standards.

Installation Notes

This tap is installed by machinists or maintenance technicians using a tap wrench, tapping head, or CNC machine spindle. Always ensure the tap is properly aligned with the pre-drilled hole before engagement to avoid tap breakage. Power down and secure the workpiece before beginning any tapping operation. Use an appropriate cutting fluid for the workpiece material to extend tool life and improve thread quality.