The Precision Twist 500-6 extra-length, aircraft extension drill bit, is a round shank bit made of HSS with a steam tempering (also called black oxide) 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. Best performance with drilling into hardened, tempered alloy steel, stainless steel, and titanium. These should be less than 30 on the Rockwell C hardness scale.
While the 500-6 series was designed for aircraft industry, they also work well for drilling into a variety of materials. The extra length and 135-degree split point drill geometry provide extra reach and ensure an accurate hole by reducing walking when the hole is started. The finish retains lubricants to aid in wear resistance and chip flow.
and away from the cutting edge. They are made to ANSI (fractional sizing) and NAS 907 type B industry standards, which helps ensure that drill bits around the world conform to the same specifications.