Keo 907-000-121 Combo Drill Countersink Size 4 Cobalt

Product Description

The KEO 907-000-121 is a combination drill and countersink designed for drilling and countersinking in a single pass. Built from cobalt high-speed steel with a bright, uncoated finish, this tool handles harder materials and higher heat better than standard high-speed steel. The body measures 5/16 inches in diameter with a 1/8-inch drill point diameter and a 6-inch overall length, making it well-suited for long-reach applications. The 118-degree drill point angle and 60-degree included countersink angle are standard configurations for machine screws and fastener seating in metal fabrication and maintenance work. It cuts right-hand and is sized as a trade size 4.

This combo drill countersink is used in metalworking, maintenance, and fabrication environments where countersinking for flathead fasteners or deburring operations are common. The double-end style and long-length designation make it appropriate for applications that require extended reach or where two usable ends extend tool life. Machinists, millwrights, and maintenance technicians working with steel, stainless steel, and other ferrous alloys are the primary users. It is suited for bench drill presses, milling machines, and handheld power tools where a secure chuck grip on the 5/16-inch body is possible.

Key Features

• Cobalt high-speed steel construction for improved heat and wear resistance in hard metals
• Bright, uncoated finish for general-purpose metalworking applications
• 118-degree drill point angle - standard geometry for drilling into steel and ferrous materials
• 60-degree included countersink angle for standard flathead fastener seating
• Double-end design provides two usable cutting ends, extending tool service life
• Long-length at 6 inches overall for extended-reach drilling and countersinking
• Right-hand cutting direction compatible with standard drill chucks and CNC spindles

Compatibility

Designed as a standard trade size 4 combo drill countersink suitable for use with bench drill presses, milling machines, and handheld power drills equipped with a chuck capable of holding a 5/16-inch diameter shank.

Installation Notes

This tool is installed and operated by machinists, maintenance technicians, or fabricators with appropriate machine tool training. Secure the body firmly in the chuck before operating and confirm the spindle speed is appropriate for the tool diameter and workpiece material before starting the cut. Always wear appropriate eye protection and secure the workpiece before drilling. Do not use this tool on materials beyond its rated hardness range for cobalt tooling.