Roasted coffee is sold in beans so as not to alter its taste and to maintain its fragrance. Considering that espresso means “made on the spot“ the grinding of each dose must occur immediately prior to the actual brewing of the coffee. The tool used for this operation is the grinder.

The most important part of this machine are the blades. There are two discs, one rotates while the other, mounted on a toothed ring nut, controls the degree of grinding.

There are two types of blades. Flat grinder blades and conical grinder blades.

There are two reasons why the conical blades are normally preferred. Up to 1000kg of coffee can be ground without signs of wear, while flat blades must be changed after 400kg. Conical blades avoid overheating as the rotating speed is lower.

As soon as blades show signs of wear it is essential they are changed.

The degree of grinding is directly related to the extraction time of the espresso. If the grind is optimal, an espresso is extracted between 20 to 30 seconds. If the extraction time is lower than that, the grind is too course. An extraction time exceeding 30 seconds indicates that the grind is too fine.

Another main component of the grinder is the doser. This devise determines the exact dose of coffee needed for an espresso.

Its design is such that the volume of coffee released is measured. The weight of the dose varies depending on the characteristics of the coffee used.