Precision Twist Drill 5999998 Reduced Shank Drill Bit

Product Description

The PRECISION TWIST DRILL 5999998 is a reduced shank cobalt drill bit designed for drilling into ferrous metals and a wide range of secondary materials. It carries a 63/64 inch (0.9844 inch decimal) cutting diameter with a 1/2 inch straight-cylindrical reduced shank, allowing it to seat in standard 1/2 inch chucks while running a larger cutting diameter. The 118-degree split point starts on contact without a center punch, reducing walking on hard surfaces. Built from cobalt steel, the bit handles the heat generated in tough ferrous applications better than standard HSS tooling. This is a right-hand cut bit with a bright, uncoated finish and regular spiral flutes. Machinists, fabricators, and maintenance mechanics are the primary users.

The 5999998 is suited for production drilling and maintenance work in ferrous metals including steel and cast iron, as well as secondary materials such as aluminum, copper, magnesium, nickel, titanium, and synthetic materials. The reduced shank design makes it practical where only a 1/2 inch chuck is available but a larger hole diameter is required without stepping up to a larger drill press or machine. It is equally at home in a floor-standing drill press or a heavy-duty benchtop machine. No coolant-through capability is present, so flood or mist cooling at the tool tip is standard practice for extended production runs.

Key Features

• Cobalt steel construction provides heat and wear resistance over standard HSS in ferrous metal drilling
• 118-degree split point reduces thrust and eliminates the need for center punching on most surfaces
• Reduced shank at 1/2 inch fits standard chucks while cutting a 63/64 inch diameter hole
• Right-hand cut with regular spiral flutes for positive chip evacuation
• Bright, uncoated finish — no coating to chip or delaminate in high-heat applications
• ANSI standards compliance for dimensional consistency

Compatibility

Designed as a Series R56CO reduced shank cobalt drill bit compatible with any drill press or machine tool equipped with a 1/2 inch or larger chuck. Suitable for ferrous metals, aluminum, copper, magnesium, nickel, titanium, cermet, and synthetic workpiece materials per supplier specifications.

Installation Notes

Installation is performed by machinists or maintenance mechanics following standard machine tool practices. Secure the 1/2 inch reduced shank fully into the chuck jaws and verify runout before beginning a cut. Ensure the workpiece is clamped securely — an unsecured workpiece can grab and rotate at breakthrough on large-diameter bits. Apply cutting fluid or mist cooling at the tip when drilling ferrous metals in production volumes to extend tool life; this bit has no internal coolant channel.