The Dormer A345 extra-length, black oxide-coated, general-purpose Morse taper shank drill bit drills holes into a wide variety of metals and synthetic materials. It can drill to a depth up to ten times the diameter of the drill size. The shank diameter is the same as the drill size.
The A345 series has a type N flute form, with a regular helix (21 to 34 degrees) angle, and performs best when drilling into magnetic soft steel or structural steel (case carburizing steel). Black oxide helps to prevent buildup and welding of material on the drill’s cutting edge when working with iron and steel. Spiral flutes act as a passageway for chip extraction from the hole and for coolant to enter the hole. Right-hand twist brings chips up and away from the cutting edge. The extra length allows for more freedom in being able to drill a wider variety of circumstances.
The principle of a Morse taper is that of the cone in the cone. The trunnion (the male portion – drill shank) and the bore (the female portion – the tool- holder) are both uniformly tapered. This system allows for torque to be transferred directly to the drill through the friction between the taper shank and the tool holder. The tang at the end of the taper is used for ejecting the drill bit from the spindle, with the aid of a drift pin.
Drilling, or hole making, is the most common metalworking operation in the world and twist drill bits are the most common type of drill bit. They can be used in hand-operated drills, standalone drill presses, or a lathe. They are made to DIN 340 industry standards, which ensure that drill bits around the world conform 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.