A typical commercial coffee bean grinder consists of 5 main parts each of which we will now explore in more detail.

Bean Hopper - The sits on top of the main body of the unit and obviously contains the roasted coffee beans that by means of gravity feed beans directly to the grindstones. A hopper that can comfortably contain a typical one kilogram bag of coffee beans is typical for commercial grinders. Most grinders these days have an automatic cut off feature that cuts the power to the grinder if the hopper lid has been removed.

For general maintenance purposes the hopper should be removed, washed with warm soapy water, rinsed and dried on a weekly basis.

Motor - The grinder motor on commercial grinders are large robust electric motors usually operated by a start/stop switch on the base of the casing. The motor should be designed so that it avoids the grindstones overheating and scorching the coffee.

Grounds Reservoir and Doser - Good quality grinders usually contain a sensor in the reservoir that senses when the coffee grounds are running low and automatically tops up the reservoir. At the base of the unit a segmented wheel or lever device allows the user to dose the correct amount of ground coffee into the filter handle of a typical espresso machine. The coffee doser is usually calibrated to dispense between six and eight grams of coffee. Beneath the doser is a cradle to hold the filter handle in the correct position beneath the dispensing hatch.

The doser should be completely emptied, cleaned with soapy water, rinsed and dried on a regular basis.

Grindstones - Located between the base of the hopper and the top of the motor are the grindstones. The top stone fits to a finely graduated screw type adjuster, set within the casing. The bottom stone is fixed to the motor drive. The distance between the two grindstones is increased or decreased by the adjuster screw mechanism. Only a very small adjustment is needed to dramatically alter the degree of grind.

Tamper - Tampers range from grinder to grinder, but are usually fixed stubs or plungers on the body of the doser. Some professional baristas prefer to use stand alone tampers made of wood or aluminium. The purpose of the tamper is to assist the operator in compacting the coffee in the filter handle so it produces a compacted wad of coffee for use in the espresso machine.

General maintenance procedures dictate that the grindstones are dismantled and thoroughly cleaned of all coffee residues, using a long stiff brush and a clean cloth.

Grindstones have a limited life and will need replacing after approximately 300-500 kilograms of coffee beans have been used.