If you’re looking for a coffee grinder, it’s important to understand the difference between each type. For example, if you’re used to a blade grinder, you will notice a significant improvement in the flavor of your coffee if you switch to a burr grinder. Therefore, it’s always best to opt for the latter. Previously, we compared blade grinder vs burr grinder in detail.
However, there are flat and conical burr coffee grinders. So, how do the two types differ, and which is better? This article explores those questions to offer a clearer understanding of which burr grinder you should choose.
Conical vs Flat Burr Coffee Grinders Summary
Any discussion about the differences between flat and conical burr grinders can be a bit technical. So, before going into greater detail, below is a summary of the two options that offers an overview of their key differences.
Conical Burr Grinder
Conical burrs are quieter and slower than flat burrs. They are also less expensive. The slower grinding speed (lower RPM) means they generate less extra heat than flat burrs and create less noise. Another advantage is there’s not as much retention of coffee grounds. These pros make conical burrs an excellent choice for most home baristas. Indeed, if you grind coffee for drip coffee, pour-over, or French press, you needn’t consider anything else.
- Creates less heat
- Fewer grinds retention
- Slow compared to flat burrs
Flat Burr Grinder
Flat burrs are noticeably faster than conical burrs, but there’s a trade-off: they’re generally louder and generate more heat while grinding. This is because flat burrs need a bigger motor, which also means they’re more expensive. However, you get a more efficient grinder for the extra money, too, which is why coffee shops often favor them. The consistent grind and efficiency make them a good choice for espresso brewing.
- More efficient
- Generate more heat
- More expensive
The Mechanical Differences Between Conical And Flat Burrs
The primary function of a coffee grinder is to force the coffee beans through a gap. On either side of the gap is a burr set that cuts and crushes the beans into particles. However, the shapes of flat and conical burrs and the way they work differ.
How Do Conical Burrs Work?
Conical burrs coffee grinders have a ring and cone burr shape that fit into one another. When grinding coffee, the outer burr is steady while the inner cone spins.
The coffee beans reach the burrs from an angled entrance above. Meanwhile, the rotating inner cone pulls the beans down to a narrower channel. The process results in the whole beans breaking into smaller and smaller particles until they’re tiny enough to use for brewing.
To tweak the grind size, you alter the distance between the inner and outer burrs. Some conical burr grinders have stepped grind setting adjustments, while others are stepless. With the latter, you can make incremental adjustments, making them ideal for espresso brewing.
How Do Flat Burrs Work?
Flat burrs have two compatible shapes that sit parallel to each other. When the coffee beans descend, the burrs spin rapidly, sucking them into the grinding teeth and kicking out the grounds using centrifugal force.
Typically, flat burrs spin to 700RPM or over. Because of this, flat burr grinders need a powerful motor. This explains why there are no manual grinders with flat burrs – it’s impossible to reach the required speed by hand.
Where flat burrs are similar to conical burrs is in the grind size, which changes the size of the gap. The larger the gap, the larger the particles that will go through.
You may think that even though conical and flat burrs look and work differently, the result will be the same. However, the ways they work change the results. Let’s examine them.
Grind Retention – Flat Vs Conical Burr Grinders
The first difference is grind retention. Because of the parallel position and rapid speed of flat burrs, they retain many more grounds. However, as we mentioned earlier, flat burrs need centrifugal force to kick the grounds out. This is in contrast to conical grinders, which use gravity. Therefore, in the latter, the grounds will naturally fall. To illustrate the point, consider the Niche Zero, a conical burr grinder that claims zero grinds remaining.
Because flat burr grinders typically retain more grounds, this affects the coffee flavor because the fresh ground interacts with the older coffee in the grinding chamber. Therefore, to ensure you brew with the freshest possible coffee in a doserless grinder, it’s good practice to purge the remaining grinds by grinding some fresh beans.
This isn’t an issue for a coffee shop that uses a large number of grinds and brews large volumes of coffee each day, but when brewing at home, it will cause considerable more coffee waste over time.
Some domestic flat burr grinders, including the DF64, address the issue by placing bellows on the hopper to reduce the retention with a few puffs.
Grind Quality And Grind Consistency
It’s hard to tell any difference between the grounds produced by a flat or conical burr grinder at first glance. However, there is undoubtedly a different feel between the two. If you touch grounds produced by a flat burr grinder, you’ll notice they are slightly softer and finer than those produced by a conical burr grinder.
However, as long as you’re using a high-quality burr coffee grinder, you’ll get pleasingly consistent grounds regardless of whether it has flat or conical burrs, particularly compared to the results from vastly inferior blade grinders. This means you can expect excellent filter or espresso coffee using either.
Nevertheless, it is more complex and technical when grinding for espresso. The distribution of grounds produced by conical burrs is bimodal. So, if you were to observe grounds from a conical burr under a microscope, you would see two particle sizes – large and small. This is a good thing for espresso because the smaller particles restrict the water flow, allowing the larger particles more extraction time.
However, flat burrs have unimodal distribution, leading to more consistent grounds. With unimodal particle distribution, you can alter the grind settings to pull longer shots. This helps creatively manipulate the espresso flavor.
Coffee’s Quality And Flavor
Because flat and conical burrs produce differences in particle distribution, each is likely to produce different flavor profiles in your espresso shots.
Usually, conical burr grinders offer bright flavors that are floral and fruity with pleasant acidity. Meanwhile, flat burr grinders bring out the darker notes like chocolatey, nutty flavors with muted acidity.
Most espresso drinkers are unlikely to notice these subtle differences unless they have conical and flat burr grinders and can sample coffee from each one after the other. However, even if you have a refined palate, the flavor can be subjective. In truth, it’s difficult to state which grinder offers the better flavors. Ultimately, it will depend on your preferences and the beans you’re using.
As we mentioned earlier, conical burrs are far slower than flat burrs. For example, the conical burr Niche Zero grinds at 330RPM, but the DF64, which has a flat burr, grinds at 1400RPM. Similarly, the conical burr Baratza Encore has a speed of 550RPM, but the flat burr of the Eureka Mignon Specialita has a 1350RPM motor.
Unsurprisingly, the more powerful the motor, the noisier it will be. So, while this might not be a distraction in a cafe, it’s something to keep in mind for domestic grinding.
Flat burrs produce more heat than conical burrs, too. Higher RPMs produce more friction, causing more heat build-up between the burrs.
So, the more rapidly the burrs spin, the more friction there will be, creating more heat while grinding. This can be an issue because heat makes the grinds less consistent, which changes the coffee flavor.
Conical burrs are normally less expensive than flat burrs. For example, it’s not unusual to find a high-end conical burr grinder for less than half the cost of a premium-quality flat grinder.
This is partly because conical burr grinders have smaller motors than flat burr grinders. However, the mechanism in a conical burr is far less complex than a flat burr, which also helps keep the price lower.
Also, many premium hand grinders offer high-quality burr sets and outstanding grind consistency at a more affordable price compared to electric grinders. That is possible since there’s no electronic part in the grinder so the cost goes to a higher quality burr set. If you don’t mainly grind for espresso, manual coffee grinders work pretty well.
Final Thoughts – Conical vs Flat Burrs: Which One To Purchase
Even though some technical differences between conical and flat burr grinders affect the overall coffee flavor, they both still make excellent coffee. In the end, which you prefer will likely come down to your taste preference.
Nevertheless, other differences are easier to pinpoint. For example, conical burrs don’t suffer from as much grounds retention as flat burr grinders. Also, conical burrs produce less noise because of their slower speed, meaning they’re less likely to disturb others. Finally, conical burr grinders won’t generate as much heat while grinding as flat burr grinders, so they’re less susceptible to heat-related inconsistencies and flavor deterioration.
On the other hand, flat burrs offer more control over the grinding process and generally produce more consistent grinds. But, of course, the larger motor of flat burr grinders leads to more noise and a higher cost.
Despite their differences, whether you choose a conical or flat burr grinder, you should see far better grind consistency than you’d get with a blade grinder. And most important of all? You’ll have far more beautiful coffee, too!