Precision Twist Drill 5997678 Cobalt Jobber Drill Bit

Product Description

The PRECISION TWIST DRILL 5997678 is a wire size No. 10 cobalt jobber-length drill bit engineered for heavy-duty drilling in ferrous and non-ferrous metals. Measuring 0.1935 inches in diameter with a 135-degree split-point angle and a web-thinned tip, this bit starts on contact without a center punch and reduces walking on hard surfaces. The straw oxide finish provides additional surface hardness and corrosion resistance. At 3.625 inches overall length with a 2.4375-inch flute length, it delivers the reach and chip clearance needed for through-hole work in structural steel, alloy steel, stainless, cast iron, and non-ferrous materials. Licensed contractors and tool-and-die machinists are the primary users.

This bit is suited for production drilling in steel and other primary workpiece materials coded P, M, K, N, and S — covering carbon steels, stainless steels, cast iron, non-ferrous metals, and heat-resistant superalloys. The regular spiral flute and tapered web geometry maintain chip flow across a range of feed rates. The straight cylindrical shank, measuring 0.1935 inches in diameter and 1.1875 inches in length, fits standard three-jaw chucks and keyless drill chucks found on benchtop drill presses, hand drills, and CNC drilling stations. The series R10CO-R15CO-R18CO designates the cobalt-content family, appropriate for harder workpiece materials where high-speed steel alone is insufficient.

Key Features

• Cobalt construction for heavy-duty drilling in hard and abrasive metals
• 135-degree split point with web thinning for reduced thrust and no center-punch requirement
• Straw oxide and bronze coating adds surface hardness and corrosion resistance
• Regular spiral flute at 13xD flute-to-diameter ratio promotes efficient chip evacuation
• Straight cylindrical shank fits standard chucks without modification
• Meets ANSI and NAS 907 standards for consistent dimensional accuracy

Compatibility

Designed for use in standard three-jaw and keyless chucks accepting a 0.1935-inch straight shank. Part of the R10CO-R15CO-R18CO cobalt jobber series.

Installation Notes

Installation and use should be performed by a qualified machinist or tradesperson familiar with cutting tool safety. Secure the workpiece firmly before drilling and confirm the chuck is fully tightened before operation. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve cut quality. Do not exceed the rated maximum drilling depth of 2.4375 inches in a single pass without retracting to clear chips.