The Mechanical Scales are so or more reliable than the electronics, and still today, they continue being a fundamental element inside the market of the purchase and sale. Although the electronic scales are the last invention, the mechanics have not disappeared of the market, on the contrary, they have been perfected. These scales are used to weigh big and voluminous masses. It is said that a scale is an instrument of mensuration of weight that have a bigger resolution than a gram and the balance is used to weigh small masses and it has resolutions of gram fractions.