Precision Twist Drill 5997740 No. 51 Cobalt Jobber Drill Bit

Product Description

The PRECISION TWIST DRILL 5997740 is a No. 51 wire-size cobalt jobber drill bit designed for production and maintenance drilling in ferrous metals and hard alloys. The bit measures 2 inches in overall length with a 1 inch flute length and a 135-degree split-point geometry that reduces walking and decreases thrust on entry. Cobalt construction provides heat resistance beyond standard high-speed steel, making this bit suitable for interrupted cuts and harder workpiece materials. An oxide and straw coating reduces friction and helps extend cutting life in repetitive drilling applications. The straight cylindrical shank seats directly into standard chucks without adapters.

This drill bit is intended for use by machinists, maintenance technicians, and trade professionals drilling steel, stainless, cast iron, and similar ferrous or high-temperature alloys. It is well suited to handheld drill motors, drill presses, and CNC machining centers where a 0.0670 inch diameter hole is required. The 15xD flute-to-diameter ratio and regular spiral flute geometry promote chip evacuation in both shallow and moderate-depth holes up to 1 inch maximum drilling depth. Web-thinned construction reduces cutting force at the chisel edge.

Key Features

• No. 51 wire size, 0.0670 inch diameter for precise small-hole work
• 135-degree standard split point reduces walking and entry thrust
• Cobalt construction for improved heat and wear resistance in hard metals
• Oxide and straw coating reduces friction and extends service life
• Web-thinned tapered web configuration lowers cutting force at the chisel edge
• Right-hand cut, regular spiral flute promotes clean chip evacuation

Compatibility

Designed for use in standard straight-shank drill chucks on handheld, bench, and CNC drilling equipment. Meets ANSI standards and NAS 907 specification. Fits Series R10CO-R15CO-R18CO tooling configurations. Primary workpiece material codes P, M, K, N, and S cover steel, stainless, cast iron, non-ferrous, and heat-resistant alloys.

Installation Notes

Installation is performed by machinists and maintenance technicians. Secure the straight shank fully into the chuck and confirm concentricity before drilling. Power down and de-energize or lock out any machine before changing bits. Follow applicable ANSI B11 machine safety standards for the drilling equipment in use. Coolant through is not supported on this bit; apply cutting fluid externally as needed for the workpiece material.