Understanding Your Commercial Coffee Grinder

Your commercial coffee grinder is an extremely important piece of equipment. You will need to maintain it and keep it clean, and you might need to adjust it daily (or even more than that if the humidity varies) to produce consistent espresso.

In a commercial espresso bar or coffee shop, you need a heavyweight grinder that can run all day without wearing out. The purpose of this article is to explain the working components of the grinder so that you will understand how to use and adjust them.

If you use flavored coffee beans, you will need two commercial coffee grinders. You will use one of them for your flavored coffees, and the other for unflavored coffees. While some coffee shop owners claim that they can use a single grinder for both types, the flavorings will impart unwanted flavors to plain espresso. Some customers will not mind this, but espresso purists will find it offensive. If you are going to offer flavors, you should either have two commercial coffee grinders, or you should use syrups, or both.

Commercial Coffee Grinder - Body

The "body" or "base" of the grinder is what makes the grinder heavy. It houses a large electric motor that will weigh over 30 pounds. It is important to have a large motor because it can produce lots of torque at relatively low speed. This allows it to grind the beans without overheating them. This is important because heat will cause some of the flavor to dissipate, and excessive heat will give the coffee a scorched or overly bitter flavor.

It is also important to have a large motor so that it can run all day without overheating. If you try to grind many pounds of beans with a smaller grinder that is meant for personal (home) use, you will burn it out and destroy it fairly quickly.

Loading Bay, Doser, and Tamper

In the front of the body, near the base, most commercial coffee grinders will have a loading bay. This is merely a protruding adapter that will hold the group handle for easy loading. You will put the group handle (with a clean filter basket) into the loading bay, and then pull the doser lever.

Coffee grinders built for home use can either come with a built-in doser, or they can come doserless. If you are using the coffee grinder for personal use, it is probably best to get a doserless grinder, since for the doser mechanism to work correctly, you will need to grind more coffee (at least six doses) than you will likely use at any time.

This is not true of an espresso bar or a coffee shop, where you will use many doses throughout the day. Therefore, commercial coffee grinders will usually have the doser function. (The exception is commercial coffee grinders built for supermarkets or coffee stores, where the customers are not purchasing beverages, but are using the coffee grinders to grind and bag their own coffee.)

Pulling the doser lever once will deposit one dose of ground coffee into the filter basket. Pulling it twice will deposit two doses, which is used to make a Doppio (a double espresso).

Above the loading bay, most commercial coffee grinders have a built in tamper. This is merely a protruding arm attached to the body that has a disk connected to the end of it that is facing downwards. The diameter of the disk is such that it will fit into the filter basket in the group handle. After you have put the right dosage of coffee grounds (one or two pulls) into the filter basket, you can push the group handle up into this disk to compact the coffee.

We recommend that you do not tamp the coffee grounds in this way. Instead, you should tamp them by hand using a technique that is explained in another of our articles.

The Chamber

The chamber is above the base, near the top of the body. The chamber lies below the grinding mechanism, and it holds the ground coffee. The dosing mechanism is at the bottom of the chamber. It is basically a rotating cylindrical disk having (usually) six triangular dosing compartments in it. The loose coffee grounds in the chamber will fill these dosing compartments.

Pulling the dosing lever simply causes the dosing disk to rotate one sixth of a revolution (60 degrees) so as to discharge the coffee grounds in one of the six dosing compartments into the filter basket inside the group handle in the loading bay. Two pulls will cause two of the dosing compartments to discharge. A dosing compartment should hold ¼ ounce (7 grams) of ground coffee.

When closing each night, it is important to empty the chamber by repeatedly pulling the dosing lever until no more coffee grounds come out. Then clean out the chamber with a small brush to remove the remaining coffee grounds. If you leave ground coffee in to chamber overnight, the grounds will get stale, and will absorb water from the air. This will change the quality of any shots pulled from this batch in the morning. Instead, store these grounds in an airtight container, and use them to make regular or iced coffee.

The Collar

The collar is at the very top of the chamber, and it controls the distance between the grinding wheels, and hence the granularity of the grind. The collar is usually disk-shaped. It can (and should) be twisted to change the granularity of the grind as conditions change throughout the day.

Adjusting the grind is very important to the quality of the espresso extraction. In professional barista competitions, each competitor is given (usually) 15 minutes just to adjust the grinder, and to calibrate the espresso shot to the grind before he (she) starts pulling the shots that are to be judged.

The collar will have a release button somewhere that allows you to rotate the collar to change the grind. If you do not find and press the release button, the collar will stay locked in place, and you will not be able to rotate it. This is very desirable - you would not want to change your grinder setting accidentally.

The Hopper and Gate

The hopper is usually (but not always) a funnel-shaped plastic chamber. The hopper is the container that holds the coffee beans that are to be ground. In commercial coffee grinders used in espresso bars and coffee shops, the hoppers will hold a few pounds of beans at any time. The hopper sits on top of the coffee grinder.

The base of the hopper fits into the collar (see above) so that gravity will allow the beans in the hopper to fall into the grinding mechanism. The base of the hopper will have a gate that closes the hopper so that no beans will flow. It is important to shut the gate before taking the hopper off of the grinder, which you might do when adjusting the collar (if you can't remember which way to turn it), and which you will do at the end of the day.

If you forget to close the gate when you remover the hopper, you will quite literally spill the beans. After closing each night, you should remove the hopper, store the unused beans in an airtight container, and clean the hopper with soap and water. Oil from the beans will accumulate on the walls of the hopper during the day, and your coffee shop will look dirty if you let this accumulate.

It is important to leave the (cleaned) hopper off the coffee grinder to dry overnight. If you put the hopper back onto the coffee grinder while it is still wet, drops of water will get into the grinder and cause the grinding wheels to rust.