A blasting machine or shot exploder is a portable source of

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movi ...

to reliably fire a

blasting cap A detonator, frequently a blasting cap, is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the last two being the most common. The commercial use of explosives uses electri ...

to trigger a main

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

charge. It is mostly used in

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the econom ...

and

demolition Demolition (also known as razing, cartage, and wrecking) is the science and engineering in safely and efficiently tearing down of buildings and other artificial structures. Demolition contrasts with deconstruction, which involves taking a bu ...

. The use of the term "machine" dates from early designs that used an

electrical generator In electricity generation, a generator is a device that converts motive power ( mechanical energy) or fuel-based power ( chemical energy) into electric power for use in an external circuit. Sources of mechanical energy include steam turbines, ...

operated by winding a rotary handle or pushing down a T-handle. Modern blasting machines are battery-powered and operated by key switches and push-buttons, and do not resemble the older designs. A typical "capacitive discharge" blasting machine works by charging a

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

from a

battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...

, then discharging the capacitor through an external circuit, called the firing line, to fire the blasting cap. While the machine is idle, an "internal shunt" is connected across the output terminals so that any stray voltages induced in the external circuit, for example by nearby radio transmitters, are harmlessly short-circuited without triggering the

. The machines also typically include an "abort" feature to discharge the internal capacitor without firing the cap. The first satisfactory magnetic induction blasting machine was constructed in 1878 by Henry Julius Smith of Mountain View, New Jersey.See: * Smith, H. Julius
"Improvement in magneto-electric machines"
U.S. Patent no. 201,296 (January 17, 1878). * Smith, H. Julius

U.S. Patent no. 353,827 (December 7, 1886). * Smith, Henry Julius, [http://pdfpiw.uspto.gov/.piw?Docid=00534289&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D0534289.PN.%2526OS%3DPN%2F534289%2526RS%3DPN%2F534289&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page "Art of blasting"], U.S. Patent no. 534,289 (February 19, 1895). * Krehl, Peter O. K., ''History of Shock Waves, Explosions and Impact: A Chronological and Biographical Reference'' (Berlin, Germany: Springer, 2009), p. 365. Its mechanism consisted of a T-handle that was pushed down; the lower end of the handle was a rack that drove a pinion, which in turn drove a high-voltage magneto, which generated the high voltage that is required to detonate the blasting cap.

In popular culture

Despite the older "T-Handle" design no longer being used, this design of blasting machine is most closely associated with

Looney Tunes ''Looney Tunes'' is an American animated comedy short film series produced by Warner Bros. starting from 1930 to 1969, concurrently with its partner series '' Merrie Melodies'', during the golden age of American animation. ...

, and the character

Wile E. Coyote Wile E. Coyote and the Road Runner are a duo of cartoon characters from the ''Looney Tunes'' and ''Merrie Melodies'' series of animated cartoons, first appearing in 1949 in the theatrical cartoon short '' Fast and Furry-ous''. In each episode, ...

, due to his penchant for attempting to use explosive materials to capture or incapacitate the Road Runner; often ending in disaster for the Coyote as the explosive either backfires, the machine does not work properly, or the T-handle gets stuck.

References

External links

*
Inside an Arbra dynamite exploder
bigclivedotcom Youtube {{Mining equipment Mining equipment Demolition