Why Grind My Own Coffee Beans? 

As a child, I remember accompanying my grandmother to a small grocery store.  About halfway down the third aisle sat a large red coffee grinder and a few bins of beans.  My grandmother would pour a couple scoops of beans in the top of the machine and close the lid.  It was my job to flip the switch!   The machine would grind away and the aroma of freshly ground coffee seemed to fill the entire store. On the way home, the aroma from that little bag would slowly begin to dissipate. By the next day, my grandmother’s pantry smelled like it did before we went shopping.

If you have ever been near a grinder, you know exactly what I am talking about.  As soon as the grinding begins, the aroma fills the room.  Immediately after coffee beans are ground, however, they begin to loose their aroma.  Further, oils are released, carbon dioxide escapes and the flavor begins to decline.  Therefore, if you want the most luscious, robust, crema-capped shot, you have to extract the shot immediately after grinding it. 

In espresso production, grinding is important for another reason too.  The grind size is perhaps the most important adjustable variable you have.  See Making Better Espresso. If you grind your own beans and the extraction time is a bit long, you can decrease the grind size.  If the extraction is a bit short, you can increase the grind size.  If you purchase your beans already ground, some of your ability to dial in an optimum shot is lost.

Does the Grinder Really Matter?

YES.  In espresso production, the grinder is crucial.  In fact, many say it is more important than the espresso machine.  The grinder must be capable of making very small adjustments to the grind size and it must be able to produce a uniform and consistent grind size.

Types of Grinders  There are basically two types of coffee grinders: blade grinders and burr grinders. 

1.)  Blade Grinder – To their benefit, blade grinders are the least expensive type of grinders and they do an adequate job grinding coffee for drip coffee makers.  The coffee beans are placed in the grinder and the grinder is turned on.  A metal blade spins around like a lawn mower blade and cuts the beans.   The longer you leave the grinder on, the finer the grind becomes.  In other words, there is no adjustment mechanism for changing the grind size. When the grinder is turned off, it’s not uncommon to find an inconsistent grind.  Some beans may be cut to powder while others remain in larger chunks.  The job is considered adequate for drip coffee makers because the paper filter brewing method is more forgiving of minor inconsistencies in grind size than the espresso brewing method. The blade grinder, however, is not recommended for making espresso.  Recall that espresso requires a very specific and uniform grind size. 

2.)  Burr Grinder  - The benefit of the burr coffee grinder is its ability to produce a consistent grind.  Burr grinders have two burrs.  Once the motor is turned on, the beans are pulled between the stationary and the moving burr and they are crushed to a predetermined size.  In addition to grinding consistently, a burr grinder grinds much more slowly than a blade grinder.  This means that less heat is transferred to the beans, creating less potential to harm the aroma and flavor.  The burr grinder is recommended for espresso brewing because of its ability to produce a uniform sized grind.   

Types of burrs  There are two types of burrs: flat-plate burrs and conical burrs.

1.)  Flat-Plate Burr – The flat-plate burr (wheel burr) grinder utilizes two flat, disc-like burrs that sit one on top of the other. Each disc has ridged edges that face each other.  When the grinder is turned on, the beans are pulled between the flat plate burrs and are crushed to a predetermined size.  

2.)  Conical Burr – The conical burr grinder utilizes two cone shaped burrs with ridges.  Like the flat-plate burrs, one bur remains stationery while the other spins.  Both burr types produce consistent grind sizes and can be found on both commercial and home grinders. The conical burr is most often found on the very low speed grinder while the high-speed grinders use flat-plate burrs.  However, low speed grinders can come with either flat or conical burrs. 

Other Factors to Consider

1.) Grinder Speed  The grinder speed is a factor perhaps more important than the type of burr.  The low speed burr grinder is considered the best because it is quieter, less messy, transfers less heat and is far less likely to bog down or clog up when grinding oily or flavored coffees. 

2.) Stepped or Stepless Grind Adjustments Burr grinders are referred to as “stepped” or “stepless” depending upon how they adjust for varying grind sizes.  On a stepped adjustment grinder, the adjustments points are preset to stop at a specific number of adjustment settings.  On a stepless grinder, there are no preset points.  Because there are no predetermined settings, you can make the smallest adjustments to the grind size.  This is ideal for really dialing in your espresso grind. 

3.) Doser or Doserless A doser is what holds the coffee immediately after it is ground.  Beans are placed in the hopper and are ground by the burrs. The ground coffee then travels through a chute and enters the doser.  The doser is a staging area of sorts. It collects the grounds and divides them into six equal amounts ranging from 5.5 to 9 grams, depending on the grinder. Often these amounts are preset and can not be adjusted.  When you pull a handle, one of the six compartments releases the preset amount of grounds into a receptacle, such as a portafilter. As the name suggests, doserless grinders do not have a doser. A doserless grinder is designed to release the grinds either directly into a portafilter or into any other container.