Below is an article by jlhufford that does a wonderful job going over the various grinding methods and each of their various advantages and disadvantages.
Coffee Grinders: Blades, Burrs, or Biceps?
In this article, we explore the different kinds of grinders, along with their advantages and disadvantages. If you plan on enjoying coffee that costs over $9 a pound, then you had better pick up some kind of grinder, so you don’t leave all that wonderful aroma in the coffee shop. The second coffee is ground, not only is a large portion of the flavor lost to the air, but the ground coffee also rapidly becomes stale, as the inside of the bean just got exposed to the outside air. The three major groups discussed will be electric blade grinders, electric burr grinders, and hand crank burr grinders. Want to better understand espresso grinders? Read this article first, then click here. So then, let’s begin.
Blade Coffee Grinders
A blade grinder like the Capresso Cool Grind uses high speed blades to grind coffee. Sounds easy enough, on to the next topic… Well, there is a bit more to it. It’s true, a blade grinder works like a dry mix blender/food processor. It chops the coffee beans into little bits. Generally, the longer you grind, the smaller the bits get. The drawback to this is the generally part. You will always get a mix of fine and coarsely ground coffee, making the electric blade grinder primarily suited for drip coffee makers that use paper filters. If you want a coarse grind, you are generally going to grind between fifteen and twenty-five seconds. We recommend using the pulse action of the grinder rather than leaving it on the whole time. You can probably get Turkish grind out of this too, but you can forget about espresso, which is more demanding of a quality and consistent grind. You can even use blade grinders to process spices, but due to volatile oils in cinnamon and other spices, it is not recommended go from spices back to coffee. So, the whole process is pretty simple, just grind longer for finer granules. Some coffee drinkers even choose to use their blender, such as a Vitamix Professional Series, to grind, but this tends to overheat the ground coffee and damage the delicate aromas. In addition to simplicity, these blade grinders are very inexpensive, ranging anywhere from $20.00 to $30.00. These are also great for travel, such as in campers, because of their small size, but for the home, you should move on to the next category: burr grinders.
Burr Coffee Grinders
This is where we get into the real meat and potatoes of coffee grinding, where sophisticated equipment stands out above the toys. Burr grinders are based on 2 hard plates (usually metal) with cutting edges that rub together. One plate is connected to a motor that turns it, and the other remains in a fixed position. Settings on the grinder allow you to adjust the space between these plates, thus determining the size (or fineness) of the ground coffee. As a coffee bean passes between the plates, it is first broken into chunks, then ground coarsely, then finely (if applicable), and then expelled from the grinding chamber by sweeping arms that turn with the plate that spins. Burrs are sized by diameter (in millimeters); the larger they are, the more coffee that can pass through in a set amount of time. Before we get too far into this, I need to get something out in the open: those boxy looking supermarket grinders in the coffee aisle are NOT burr grinders. These are more accurately called bulk grinders or mills. Great for drip, percolator, and sometimes French Press coffee; bad, bad, bad for espresso. The reason for this is in the grinding “burrs,” which we are about to dive into. Household grinders carrying the name “disk-type” or “burr mill” are miniature versions of these with the same brewing restrictions. Now that I feel better…. moving on… There are two main types of burr grinders, flat burr and conical burr, and these are classified as either household or commercial grinders. Search the internet and you will find countless arguments over which is better. Each side has valid points, but that is not our focus here. What’s important is for you to find the grinder that best suits your needs. Also, it should be noted that commercial can be used in the home setting, but not vice versa.
Once the most common type of burr grinder, the flat burr grinder is typically used to grind coffee in the home or cafe for espresso. A flat burr grinder’s plates are placed one on top of the other. They are typically made of hardened steel, though sometimes ceramic, and they are usually identical. The bottom is attached to the motor and always spins. Depending on the manufacturer, either one may be the one that is adjusted up or down for fineness. Beans enter the chamber from the top and move laterally through the burrs before being swept into the chute. As the beans are ground, the force would push the burrs apart from each other if they weren’t properly secured. For this reason, most flat burr grinders have burrs mounted onto cast metal such as brass or aluminum, and in some cases a highly durable nylon mold is used. This makes the grinder cost more, typically over $300 for home grinders and from $500 to several thousand for commercial. At JL Hufford, we tend to offer home and some light-duty commercial, but we can order any full-sized commercial grinder from the manufacturers that we sell. Flat burr grinders are almost exclusively used for fine grinds like espresso, with the exception of the critically acclaimed Baratza Vario, which has a unique fineness adjustment that has rocked the industry.
The most common household burr grinder is the conical, and it is almost always more affordable than flat burr. Mind you, this doesn’t mean it has an inferior mechanism, it just doesn’t cost as much to build. The 2 burrs in a conical grinder are not at all identical as found in the flat burrs. They consist of an outer ring burr, and an inner cone burr (hence the name). Coffee beans pass through vertically before being swept out the chute. Because of the alignment of the burrs, the force of the coffee pushes outward rather than upward. Household conical burr grinders do not require the heavy cast mountings for this reason, because the outer ring cannot be pushed outward by the force. Conical burr grinders typically spin more slowly than flat burr grinders, thus minimizing the heat generated by friction (read: keeps coffee aroma intact). Conical burr grinders produce an amazingly high-quality grind for the money, especially in the case of the burr sets used by the Ascaso I-2 and Pasquini Lux. The reason for this is that the design of the burr edges creates a larger overall cutting surface, especially in the coarse range. The tradeoff is slower output in terms of grams per second and, strangely enough, more noise. The conical burr grinder is the best choice for drip, percolator, vacuum and French Press coffee, and for the designs just mentioned above, a superior value for espresso.
As mentioned earlier, there are some grinders that would, upon simple inspection, appear to be burr grinders, but are in fact mills. The Grindmaster and Bunn grinders you see in your supermarket fall into this category. The grinding plates used have an uneven “dragontooth” design. Though they lack the consistency of fineness, these grinders are, surprisingly enough, a fantastic grinder for drip and auto drip brewing. Odds are, you won’t have one of these in your home, and since you need to grind just before brewing for the best flavor, this grinder should be your last resort or a crutch while you wait for your new grinder to arrive.
Manual Crank Grinders – Biceps
Okay, truth be told, I just wanted another “B-word”, “bicep”, in the title. This category is actually a subcategory of the burr grinder category. The major difference is that the driving force is not an electric motor, but your arm, which cranks a set of blades or burred plates. However, since most quality hand crank grinders are built with a minimum number of parts, they will outlive most electric burr models for fewer than one hundred dollars. Even better, and this one is VERY important to me, most of these grinders AREN’T PLASTIC! So, the grounds hopper doesn’t get that static-y mess of grounds all over its walls or your counter. Most of these units have a wooden or porcelain grounds hopper. The drawback (for some) is the work. And most manual grinders come with only one grinding range: Automatic Drip. But, if you have the time and energy, the grind from one of these quality mechanisms will be much more consistent than a blade grinder, and certainly less noisy. All in all, for serious coffee drinkers, a burr grinder is the way to go. And, in the past two years, great leaps have been made in burr grinder technology. But there is still a ways to go, and that way focuses primarily on robustness of the burr assembly. At the end of the day, though, even a shoddy burr grinder beats any blade grinder.