Precision Twist Drill 5997784 Cobalt Jobber Drill No. 40

Product Description

The PRECISION TWIST DRILL 5997784 is a No. 40 wire-gauge cobalt jobber-length drill bit designed for heavy-duty drilling in ferrous and non-ferrous metals. It carries a 135-degree split point with web thinning, which reduces the force needed to start a cut and helps prevent walking on hard surfaces. The bit measures 2.3750 inches overall length with a 1.3750-inch flute length and a 0.0980-inch diameter straight shank. The straw oxide finish provides additional lubricity and surface hardness. This bit is installed by machinists, maintenance technicians, and metalworking tradespeople working with drill presses, CNC machines, and hand-held power drills.

This jobber drill is suited for general-purpose drilling in steel, stainless steel, cast iron, aluminum, and non-ferrous alloys, consistent with its P, M, K, N, and S workpiece material codes. The cobalt high-speed steel construction handles elevated cutting temperatures better than standard HSS, making it appropriate for work in harder steels and production drilling where heat buildup is a concern. The regular spiral flute and tapered web configuration promote efficient chip evacuation in standard through-hole and blind-hole applications. It conforms to ANSI and NAS 907 standards and belongs to the R10CO-R15CO-R18CO series.

Key Features

• Cobalt high-speed steel construction for improved heat resistance in hard-metal drilling
• 135-degree split point with web thinning reduces thrust and prevents bit walking
• Straw oxide finish adds lubricity and surface protection
• Regular spiral flute with tapered web for consistent chip evacuation
• Right-hand cutting direction, straight cylindrical shank for standard chuck compatibility
• Meets ANSI and NAS 907 standards for heavy-duty drill bit performance

Compatibility

Designed as an OEM-compatible replacement or direct addition for applications requiring a No. 40 wire-gauge cobalt jobber drill bit. Part of the PRECISION TWIST DRILL R10CO-R15CO-R18CO series. Compatible with standard 3-jaw drill chucks accepting a 0.0980-inch straight shank.

Installation Notes

Installation and use of this drill bit should be performed by qualified machinists or tradespeople familiar with proper workholding and drill press or power-tool safety procedures. Secure the workpiece firmly before drilling and confirm chuck grip on the full shank diameter before operation. Do not exceed the recommended maximum drilling depth of 1.3750 inches without retracting to clear chips. Coolant-through is not supported on this bit; use appropriate cutting fluid applied externally when drilling harder steels to manage heat.