|
History The earliest drills were probably bow drills. The invention of the electrical drill is credited to both Arthur James Arnot *, in 1889, at Melbourne, Australia and Wilhelm Fein *, in 1895, at Stuttgart, Germany. In 1917, Black & Decker patented a trigger-like switch mounted on the handle. Types There are many types of drills; some powered by hand and others using electricity or compressed air as the motive power. Drills with a percussive action (such as hammer drills, jackhammers or pneumatic drills) are usually used in hard materials such as masonry or rock. As well, drilling rigs are used to bore holes in the earth to obtain water or oil. An oil well, water well, or holes for geothermal heating are created with large drill rigs up to a hundred feet high. Some types of hand-held drills are also used to drive screws. Hand tools A variety of hand-powered drills have been employed over the centuries. Here are a few, starting with approximately the oldest: Electric Drill Hand-held electric drills are ubiquitous. They usually look like a pistol, with a trigger-like switch. They are also used for driving screws and are often provided with a hammer action which makes them capable of being used as masonry drills. In fact, screw guns or electric screwdrivers are generally suitably modified drills. These drills typically employ a universal motor with brushes. The original designs featured a single forward speed with a simple on-off action of the trigger; they could operate equally well on AC or DC power. Modern variable speed drills contain solid state phase control circuits that limit their use to AC power only. As a tradeoff, the electronics now give them variable speed, reversibility and torque control. Hammer Drill The hammer drill is similar to a standard electric drill, with the exception that it is provided with a hammer action for drilling masonry. The hammer action may be engaged or disengaged as required. Rotary hammer drill The rotary hammer drill (also known as roto hammer drill or masonry drill) is an electric drill type dedicated to drilling holes in masonry. The rotary hammer drill is a percussion drill that uses a weight to create the impact force on the masonry bit. Generally, the drill chuck of the rotary hammer drill is designed to hold SDS drill bits. Some styles of this drill are intended for masonry drilling only and the hammer action cannot be disengaged. Other styles allow the drill to be used without the hammer action for normal drilling. Cordless drills
Drill press
Geared head drill The geared head drill is identical to the drill press in most respects, however they are generally of sturdier construction and often have power feed installed on the quill mechanism, and safety interlocks to disengage the feed on overtravel. The most important difference is the drive mechanism between motor and quill is through a gear train (there are no vee belts to tension) this makes these drills suitable for the larger sizes of drill bits (16 mm or 5/8ths" upwards) which would normally stall in a drill press. Radial arm drill A radial arm drill is a geared head drill that can be moved away from its column along an arm that is radiates from the column. These drills are used for larger work where a geared head drill would be limited by its reach, the arm can swivel around the column so that any point on the surface of the table can be reached without moving the work piece. The size of work that these drills can handle is considerable as the arm can swivel out of the tables area allowing an overhead crane to place the workpiece on the fixed table. Vices may be used with these machines but the work is generally bolted to the table or a fixture Mill drill Mill drills are a lighter alternative to a milling machine, they combine a drill press (belt driven) with the x y co-ordinate abilities of the milling machines table and a locking collet that ensures that the cutting tool will not fall from the spindle when lateral forces are experienced against the bit. Although they are light in construction they have the advantage of space saving combined with versatility and are suitable for light machining which may otherwise not be affordable. Related tools See also | ||||||||||||||
|
| |||||||||||||||
 |
|
| |