Drill
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Hand held
Bit_and_brace.JPG
A drill is a tool with a rotating drill bit used to bore holes. The twist drill is most common form, and consists of a cylindrical metal rod with two helical flutes or grooves spiralling along its length. Straight flutes are also used. The drill bit is gripped by the chuck of the drill at one end, with the other end pressed against the target material and rotated. The earliest drills were probably bow drills.
The tip of the drill bit does the work of cutting into the target material, slicing off thin shavings or grinding off small particles. This debris is carried up and away from the tip of the drill by the fluting, falling out of the helical grooves once it has been lifted clear of the hole. Lubricants and coolants (i.e. cutting fluid) are also sometimes used, with the fluting providing channels for these as well.
Modern
ElectricDrill.JPG
A drill press (aka pillar drill) is a drill mounted so that the drill can only move in the direction of the drill bit.
DrillPress.jpg
Drills are commonly used in woodworking and metalworking, especially softer metals such as iron. Straight fluting is used for copper or brass, as this exhibits less tendency to "dig in" to the sides of the hole than helical fluting. For heavy feeds and comparatively deep holes oil-hole drills can be used, with a lubricant pumped to the drill head through a small hole in the bit and flowing out along the fluting. A conventional drill press arrangement can be used in oil well drilling, but is more commonly seen in automatic drilling machinery in which it is the workpiece that rotates rather than the drill bit.
A drill can also bore holes in the earth to obtain water or oil. An oil well, water well, or holes for geothermal heating are created with a large drill rig up to a hundred feet high.
History
The electrical drill was invented in 1895, by Wilhelm Fein, in Stuttgart, Germany.
In 1917, Black & Decker patented a trigger-like switch mounted on an handle.
See also
External link
- air drill or pneumatic drill (http://ober.nease.net/ober_tools.htm)de:Bohrmaschine
fr:Chignole nl:boor (gereedschap) ja:ドリル pl:Wiertarka fi:pora