The Precision Twist 500-12 extra-length, aircraft extension drill bit, is a round shank bit made of HSS with a Steam Tempering finish. It is suitable for drilling to a depth up to four times the diameter of the drill. The shank diameter is the same as the drill size. For best performance, use for drilling into hardened, tempered alloy steel, stainless steel, and titanium, all of which should be less than 30 on the Rockwell C hardness scale.
While the 500-12 series was designed for the aircraft industry, it also works well for drilling into a variety of materials. The extra length and 135-degree split-point drill geometry provide extra reach and ensure a more accurate hole by reducing walking when the hole is started. The finish retains lubricant to aid in wear resistance and chip flow.
Drilling, or hole making, is the most common metalworking operation in the world. Twist drill bits are the most common type of drill bit used. Twist drill bits can be used in hand-operated drills, standalone drill presses, or a lathe. The flutes of the drill bit act a passageway for chip extraction from the hole and for coolant to enter the hole. These drill bits have a right-hand twist that brings the chips up and away from the cutting edge. They are made to NAS 907 type B industry standards, which ensure that drill bits around the world, confirm to the same specifications.
Together, the Precision Twist and Dormer brands represent a strong tool brand for high-productivity carbide and high-speed steel drill and tap products. Precision was founded in 1952 in Crystal Lake, IL. Dormer Tools, founded in 1913 in Sheffield, England, is known for innovative metalworking products.