Technology and our changing world high Technology

FILING AND GRINDING
Files and grinders are used to remove metal from a workpiece toat has been shaped by some other tool, such as a chisel or hacksaw. Abrasives are used to smooth and polish metal. They will all be discussed in this unit.
Files
Files vary in length, shape, type of cut, and coarseness of cut.

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  Length. Regular files range in length from 3” to 20”. The 10” file is best for general use.
  
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  Shape. Common shapes of files are rectangular, square, round, half­round, and triangular.
  
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  Type of Cit. The type of cut indicates tire way teeth are formed on the file face. A single-cut file has the teeth cut in one direction this file is good for finishing work. A double-cut file has two rows of teeth cut in opposite directions. This file is used to remove large amounts of metal quickly. A curved - tooth file is used on soft metal, such as aluminum and copper, because its teeth do not clog easily. A rasp has separate, shaped teeth. It is used on wood and very soft metals.
  
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  Coarseness. Coarseness indicates the number of teeth on the file in relation to its length. The six common grades of coarseness are rough, coarse, bastard, second cut, smooth, and dead smooth.
  

Kinds of files
Of tire several hundred kinds and sizes of files, only a few are needed by most metalworkers.

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  The mill file (A) is used for drawfiling, finish filing, shaping, and tool sharpening.
  
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  The triangular file (B) is double cut. It is used for forming grooves, squaring holes, and filing in sharp corners.
  
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  The hand file (Q is double cut. One edge has no teeth, to allow filing in corners when one surface should notbe filed.
  
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  The half-round file (D) is double cut. It has a flat side used for filing on flat and convex (curved outward) surfaces. The rounded back is good for filing concave (curved inward) surfaces.
  
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  Vae. round file is used for dressing the inside of holes and curves.
  
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  The curved-tooth file (F) is used on copper, brass, and aluminum. The teeth are not easily clogged.
  
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  The needle, or jeweler’s, file is for very fine filing. It is made in a wide variety of shapes, sizes, and degrees of coarseness.