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## Belt Sander 

The belt sander uses an endless abrasive belt driven by an electric motor to sand down metal parts much like the disk sander unit. The abrasive paper used on the belt comes in different degrees of grit or coarseness. The belt sander is available as a vertical or horizontal unit. The tension and tracking of the abrasive belt can be adjusted so the belt runs in the middle. [Figure 4-30] 

## Notcher 

The notcher is used to cut out metal parts, with some machines capable of shearing, squaring, and trimming metal. [Figure 4-31]  The notcher consists of a top and bottom die and most often cuts at a 90° angle, although some machines can cut metal into angles up to 180°. Notchers are available in manual and pneumatic models able to cut various thicknesses of mild steel and aluminum. This is an 

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excellent tool for quickly removing corners from sheet metal parts. [Figure 4-32] 

## Wet or Dry Grinder 

Grinding machines come in a variety of types and sizes, depending upon the class of work for which they are to be used. Dry and/or wet grinders are found in airframe repair shops. Grinders can be bench or pedestal mounted. A dry grinder usually has a grinding wheel on each end of a shaft that runs through an electric motor or a pulley operated by a belt. The wet grinder has a pump to supply a flow of water on a single grinding wheel. The water acts as a lubricant for faster grinding while it continuously cools the edge of the metal, reducing the heat produced by material being ground against the wheel. It also washes away any bits of metal or abrasive removed during the grinding operation. The water returns to a tank and can be re-used. 

Grinders are used to sharpen knives, tools, and blades as well as grinding steel, metal objects, drill bits, and tools. Figure 4-33  illustrates a common type bench grinder found in most airframe repair shops. It can be used to 

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