Precision Twist Drill 5997746 Cobalt Jobber Drill No. 31

Product Description

The PRECISION TWIST DRILL 5997746 is a cobalt jobber-length drill bit designed for heavy-duty drilling in steel and other demanding materials. Sized at wire gauge No. 31 (0.1200 inches decimal), it features a 135-degree split point with web thinning for fast, accurate starts without center-punching. The straw oxide finish reduces friction and extends tool life in production drilling environments. At 2.75 inches overall length with a 1.625-inch flute, this two-flute, right-hand spiral bit meets ANSI and NAS 907 standards and is built for the rigors of metalworking shops and field fabrication. Licensed machinists, millwrights, and metal trade technicians are the primary users.

This bit is suited for drilling steel, cast iron, aluminum, and non-ferrous metals in general-purpose and production applications. It falls within the R10CO-R15CO-R18CO series and fits straight-chuck drill presses, hand drills, and CNC drill heads accepting a 0.1200-inch straight cylindrical shank. Workpiece material codes P, M, K, N, and S indicate broad metal-type compatibility. The 14xD flute-to-diameter ratio supports standard jobber-length drilling depth up to 1.625 inches without parabolic flute geometry.

Key Features

• Cobalt high-speed steel construction for heat resistance in steel drilling
• 135-degree split point with web thinning for self-centering starts
• Straw oxide finish reduces friction and resists corrosion
• Right-hand spiral flute with regular spiral geometry for consistent chip evacuation
• Meets ANSI and NAS 907 specifications for dimensional accuracy
• Tapered web configuration adds rigidity at the cutting tip

Compatibility

Part of the PRECISION TWIST DRILL R10CO-R15CO-R18CO cobalt jobber series. Fits any chuck or collet accepting a 0.1200-inch straight cylindrical shank. Suitable for workpiece materials designated P, M, K, N, and S per ISO material classification.

Installation Notes

Installation is performed by machinists and metalworking tradespeople using standard drill presses, hand drills, or CNC spindles. Secure the straight shank fully in the chuck or collet before operation and verify zero runout when precision is required. Always wear appropriate eye protection and secure the workpiece before drilling. Allow the bit to cool between deep passes in hard steel to avoid overheating the cobalt substrate.