Mechanical tools

  Drilliing machine(portable type) . the different types of portable drilling machines .distinctive features and uses Necessity Portable hand drills of different types are used for certain jobs which cannot be handled on stationary drilling machines. Types There are  two types of portable drilling machines, power operated and hand operated. Power operated drilling machines Electric hand drill(light duty) These are available in different forms. The electric hand drills has a small electrical motor for driving the drill. On the end of the spindle, a drill chuck is mounted. Electric hand drills used for light duty will have, usually, a single speed. Electric hand drill (heavy duty) This drill  has an additional features,the drill speed can be varied through a system of gears. This is particularly used for  drilling larger diameter holes. Pneumatic hand drill This type of drill is operated by compressed air. An air driven motor is housed in the casing, and a handle is fi...