Best Cobalt Drill Bits

The Drill America DWD29J-CO-PC Qualtech jobber length drill bit set contains 29 cobalt steel drill bits with gold oxide finish in inch sizes 1/16" to 1/2" (1/64" increments). A self-centering 135-degree split point penetrates hard material without a pilot hole and produces smaller chips that reduce clogging compared to a 118-degree point. Cobalt steel provides extended tool life compared to high-speed steel drill bits, and maintains the tool's toughness and hardness in high drilling temperatures. A gold oxide finish acts as a lubricant and provides wear resistance, and the round shank accommodates most drill chucks. The set comes in a plastic index case with labeled compartments for identification and organization. Drill bits conform to American National Standards Institute (ANSI) standards.Drill bits are cutting tools used to make holes in a range of materials using machines such as handheld portable drills, machining centers, and lathes. Drill bits come in a variety of lengths and types, the most common of which is the twist drill bit. The round, twisted shaft of the twist drill bit typically has two cutting edges and flutes. The helical twist of the flutes brings chips up and away from the cutting edges and allows for coolant to reach the cutting edges. Jobber length twist drill bits, the most common length of twist drill bit, offer a good compromise of length and reach to work with the widest range of materials and applications. Mechanic's length twist drill bits (also called maintenance length) are a little shorter than jobber length and less prone to deflection when drilling. Short length twist drill bits (also called stub or screw-machine length) are the shortest and stiffest twist drill bits, helping to reduce the chance of deflection or breakage when drilling. Reduced shank drill bits (also called Silver and Deming drill bits) have a shank that is smaller in diameter than its shaft, permitting drilling machines with either a 1/2" or 3/4" drill chuck to crea... [Read More]