Scissors. A pair of scissors is really two knife blades joined together to form a double lever. Each blade operates as a lever of the first class (see Lever ). A pin or bolt holds the blades together and acts as their common fulcrum (support). The user squeezes the open scissors handles together to apply pressure against both sides of the material, which then is cut.
To most people, scissors and shears refer to the same instrument. But, in the hardware trade, shears refers to scissors with blades more than 6 inches (15 centimeters) long. The handles of scissors usually have rings of equal size. Most shears have a larger ring on one handle for the four fingers of the cutting hand. The thumb of the cutting hand fits through the other ring. Scissors and shears range in size from tiny manicuring scissors to giant, power-operated shears that cut scrap metal for steel-mill furnaces. Pinking shears, or pinking scissors, have sawtooth edges. They are used to give cloth a scalloped edge, which keeps the material from raveling.
Scissors developed shortly after people learned how to make knives. Sharp, sturdy scissors were developed in the late 1200’s.
