June 28, 2021

Coffee grinder burrs: What should home consumers look for?

For home baristas, a coffee grinder is an important investment, and making an informed decision when you buy is important.

The home grinder market has exploded in recent years, not least to keep up with the incredible growth in home coffee consumption through 2020. In response, many grinder manufacturers have rolled out new models or started making improvements to existing home grinders – including to the burr sets they use.

To learn more about grinder burrs and what consumers should look for, I spoke to two Laurent Denys from Home Barista, and Bas van de Steeg, an independent home barista expert. Read on to find out what they told me. 

You might also like our article on “guest coffees”

ground coffee

Why a burr grinder?

There are two main types of coffee grinder: burr grinders and blade grinders.

Blade grinders are simpler and generally more cost-effective than burr grinders. They get their name from the sharp blades used to grind the coffee. As the blades spin for longer, the grind size gets finer and finer, meaning that your control is generally linked to duration rather than blade shape or size. 

Blade grinders are often not especially precise or accurate, as this method makes it very difficult to control and repeat a specific grind size. As you want the most even particle distribution possible when extracting coffee, repeatability, precision, and consistency are all important. 

In contrast, burr grinders are much more precise. These grind coffee between two ridged metal discs or plates (known as burrs). The grind size is determined by the distance between the two burrs – the closer they are, the finer the grind size will be, and vice versa.

Burr grinders give you the ability to make precise incremental tweaks, whereas blade grinders generally do not. This gives the user the ability to choose a grind size with much more control, and therefore a better chance to extract the flavours from their ground coffee in an even and uniform way.

Laurent says: “The most important thing for coffee lovers is the consistency of the grinder, in terms of grind size.

“Burr grinders produce ground coffee that is [closer to] uniform and more consistent. This consistency makes a huge difference in the quality and flavour [in the final cup].”

grinder burrs

What should you look for in a home grinder burr set?

Despite being a clear winner over blade grinders, not all burr grinders are created equal. Burrs can be made in different shapes and sizes, from different materials, and even aligned in different ways.

Shape

There are two main burr shapes: flat and conical. The debate over which is “better” continues to this day.

Conical burrs are often used in modern hand grinders, while flat burrs are generally more popular with the manufacturers of high-quality electric grinders.

Laurent says: “There is a slight difference in how the two types work, but in general, the results are similar. 

“Flat burrs are generally more expensive and more consistent, while conical burr grinders are often more affordable and quieter.”

Flat burrs also retain more heat. This is less likely to be an issue at home than in a coffee shop, but if you’re grinding a large number of doses in quick succession, the burrs will be more likely to heat up – which in turn affects grind consistency.

Size

Grinder burrs come in a range of different sizes. This measurement is usually given in millimetres (mm) as the diameter of the grinder’s outer (larger) burr. 

Electric home grinder burrs typically start at around 40mm, while commercial models begin around 60mm and can go upwards of 100mm. As burr size increases, so too does the size of the grinder itself.

Bas says: “Generally speaking, the larger the burrs, the better the performance. 

“Grinders with larger burrs are more stable, quicker, and more efficient, and generally require fewer grind adjustments.”

For instance, the G-IOTA grinder features 64mm flat burrs which spin at 1,400rpm. While this is quite large for a home grinder, the G-IOTA is still reasonably compact at 7kg, and can grind 18g of coffee for espresso in just 13 seconds.

Bas adds: “It isn’t just about burr size, however. Geometry and alignment are also important. 

“With larger burrs, smaller deviations are magnified. This means that with larger burrs, small changes and proper alignment matter even more compared to small burrs.”

Ultimately, most high-quality home grinders will have burrs of around 40mm and above. As you go higher, you will likely find that the grinders become more expensive and less compact for a home kitchen setup. 

grinder burrs

Alignment & accuracy

With grinder burrs, alignment and accuracy go hand in hand. If your burr set is not accurately aligned, that perfect grind size will become much harder to achieve. 

“Proper alignment is mandatory for achieving [good] particle distribution,” Bas explains. “And with larger burr sets, this matters even more.

“If there is too much [space] between the burrs, it becomes impossible to get [perfect] particle distribution. And smaller and larger particles extract differently, so you don’t want variance in the cup – otherwise this leads to under and overextraction at the same time, making a well-balanced cup of coffee impossible.”

If your burrs aren’t properly aligned, consistency decreases and you will be able to taste it in the cup – even if every other part of your grinder is working perfectly.

Laurent adds: “The main issue with pretty much all grinders on the market is that they are generally not designed to be realigned or even checked for alignment. 

“If you can’t test whether a grinder runs true or not, you’re going in blind and guessing. We’re not saying that people shouldn’t try and align burrs themselves – just that there’s no way to assess how good the method of alignment really is.” 

As well as this, burrs also shift over time and through regular use, causing them to become slightly misaligned. This is much more of an issue in a café setting rather than at home, as a commercial grinder is likely to see a lot more use.

“Every grinder should be properly aligned out of the box,” Bas adds. For instance, with the G-IOTA, a precision accuracy is used to calculate alignment, no matter whether a custom or stock burr set is used.

burr set

Material

Coffee grinder burr sets are generally either metal or ceramic. Metal burrs are more durable, more expensive, and often more precise, while ceramic burrs retain less heat.

However, even with metal burrs, different materials and finishes can be used to keep temperatures lower and combat heat retention.

Laurent says: “[From my experience], I would always try to avoid a ceramic burr set.

“Yes, they are cheaper, and they do grind the coffee, but ceramic teeth are generally not very sharp and their edge holding capability is poor. They produce too much dust and they affect particle size and distribution, resulting in a ‘masked’ taste profile in your cup.”

Some grinders will also allow you to change the burrs if the stock set isn’t suitable for you.

For instance, Laurent says that the G-IOTA uses stock 64mm flat burrs made from hardened steel, designed by Italmill. However, these can be replaced with aftermarket burrs manufactured by a specialist such as Sung Sim Precision (SSP). These premium aftermarket burrs are often treated in a unique way to improve their performance.

“A solid cup always starts with a steel burr set. It really doesn’t matter that much if it is a flat or conical burr set,” Laurent says.

“Normal steels are relatively easy to cut, but they will oxidise and rust. To make your burrs last and and keep them sharp, they should be hardened through heat treatment or coated with a thin layer of a harder substance (such as titanium).”

burr set

Upgrading or replacing your burr set

Generally speaking, home grinders will come equipped with a standard or “stock” burr set. However, more experienced home baristas who want more control over their equipment may want to upgrade the burr set to really improve grind consistency.

Over time, burrs can also rust or wear if they are not properly maintained, meaning that they might need to be replaced.

In either case, you can choose to replace or upgrade your burr set, which means that you don’t need to buy a whole new grinder. Furthermore, when upgrading, better materials, coatings, and even burr realignment can all help you improve consistency.

“Changing burrs is not a difficult job on most grinders, and some users change their burrs because they want to upgrade their grinder and change the taste profile,” Bas says.

Those looking to upgrade their grinder with higher-quality burrs can even choose to purchase “aftermarket” burrs from specialist manufacturers, such as SSP

“Many grinders can be equipped with different SSP burrs,” Bas explains. “My G-IOTA has ‘unimodal’ SSP burrs. I can use it to grind high-quality filter roast, and get a pleasant cup with clarity and acidity. But if I try [the same with another grinder] then the cup is undrinkable.”

While this is not likely to be necessary for those who are at the beginning of their specialty coffee journey, upgrading or replacing your grinder burr set can be a way for experienced home baristas to improve the quality and consistency of an existing grinder.

coffee burr grinder

Choosing a grinder for your home coffee setup is by no means a simple decision. There are so many details and factors to consider, from price point and quality to consistency.

While the burr set is not the only thing you should consider, it’s a key component to keep in mind, and knowing more about what you should look for in your grinder burrs will help you make a more informed decision.

Understanding how the size, material, alignment, and shape of your burr set affect the grinder will ultimately give you a better idea of the grinding process, and help you make a more informed decision.

Enjoyed this? Then try our article on the evolution of hand grinders.

Photo credits: Nicholas Lundgaard, Home Barista, Bas van de Steeg

Please note: Home Barista is a sponsor of Perfect Daily Grind.

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