Machine History Paper - IET 101 4/24/07 Due:4/26/07...

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IET 101 4/24/07 Due:4/26/07 Evolution of the Drill The earliest type of drill was known as a bow drill. This was an ancient tool usually used to make fire, but was also used for primitive woodworking and dentistry. It consisted of a bearing block or handhold, a spindle or drill, a hearth or fireboard, and a simple bow. The spindle was carved to reduce friction at one end and maximize it at the other. Another primitive type of drill was known simply as the Hand Drill. This used a method similar to the bow drill, but used a longer, thinner spindle. Also, instead of a bearing block and bow combination, the downward pressure and spinning was done by rubbing the hands together around the spindle. The invention of the first electrical drill is credited to Mr. Arthur James Arnot, in 1889. Then Wilhelm Fein invented the first portable electric drill in 1895. Early cordless drills started with interchangeable 7.2V battery packs, and over the years the battery voltage has been increased to 18V and higher, allowing these tools to produce as much torque as many mains-
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Machine History Paper - IET 101 4/24/07 Due:4/26/07...

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