Service Sphere on grinder selection

By Maurizio Marcocci, Director of Service Sphere.

When it comes time to setting up the right coffee equipment, the varied selection of shiny toys to consider can be quite overwhelming.

While so many people consider the espresso machine to be one of the most important pieces of café equipment, don’t underestimate the importance of selecting the right grinder and maintaining its care for optimum extractions and flavour in the cup.

The determining factor when it comes to in-cup quality is your coffee grinder.

So arguably, your grinder selection takes precedence over your coffee machine selection.

When making a purchase, there are three main things to consider when deciding which grinder will best slice and dice your beans into tiny fragments: consistency, volume requirements, and grinder version (either automatic or electronic, flat or conical burrs).

Automatic grinders will grind the whole bean into a coffee chamber for the user to then dispense through the pull of a lever. Electronic grinders however, will grind and deliver a set amount of coffee straight into a portafilter (grind on demand).

But to make the right decision, consider the following questions:

– How experienced are your staff?
If your staff are inexperienced, you will need to provide the easiest solution possible for grind adjustment (i.e. automatic grinders).

– What’s your volume of coffee per week?
The answer to this will determine a lot, as will the volume you do at a particular time of the day: whether your coffee volume is spread throughout the day, or peak periods, such as the morning, or two hours of the day. I like to recommend this rule of thumb:

High volume cafés (40 kilograms + per week) or inexperienced staff = automatic grinder

Low to medium volume (under 10 kilograms per week) = electronic grinder

The reason I recommend that high volume cafés consider an automatic grinder is because not only does it save time, but it will also improve workflow. Electronic grinders not only require a grind adjustment, but also require a dose adjustment (explained later). Also, most electronic grinders have a resting time. For example: 30 seconds on (grind), 30 seconds off (rest). Take note of this and respect it. If you don’t, the grinder motor temperature will rise and has the potential to overheat.

If you’re a high volume café, think how fast you pump out your morning coffees. Do you have 30 seconds for the grinder to  rest?

Flat vs conical burrs
There are two types of burr grinders – conical and flat. Both types will grind your coffee; the main differences between the two are their shape, surface area and consistency.

Flat burrs have two identical and parallel rings that are serrated on the sides that face each other. They are generally cheaper and have a shorter lifespan. The surface area of the flat blades have high contact with the beans.

Conical burrs are made up of two cone-shaped burrs with ridges that crush the coffee. They are generally more expensive and have a longer lifespan compared to flat burrs. Due to their shape and smaller surface area, these grinders take longer to wear in and provide a consistent grind.

Common user errors
At Service Sphere we are privy to a whole range of operational grinder issues, but a great portion of those come down to user error. It’s important to care for your grinder the way you would maintain your espresso machine. Some of the most common errors that lead to grinder faults include:
Lack of cleaning
Grind set incorrectly
Changing dose times and grind settings on grind-on-demand models

It’s important to clean your grinder, just like you would clean your espresso machine. Do it daily. Oils from the beans will build up in the hopper so it’s important to remove it and wash it with warm, soapy water, letting it dry completely before filling it with beans. It is also important to clean out your doser, by simply using a small brush. Some brands feature an anti-static mesh grid. This grid reduces build-up in the dosing chamber, prevents coffee from spraying out, and is available in different sizes for different coffees. However, if you don’t clean this grid often, coffee will build up in the mesh and cause blockages.

How frequent you change your blades will be subject to the manufacturer’s recommendation and specific brand/model, so check with your technician if you’re not sure. If you have experienced staff, removing the blades to clean and check their wear is a good idea. In some models, such as the Eureka grinders, you can take the blades out to clean them, without having to re-calibrate the grind setting once you re-insert them. However, in other brands, be aware that if you remove the blades to check or clean them, you will need to re-calibrate your grind setting. Only remove the blades for cleaning if you have the technical skills to do this. If not, leave it for a technician to do in a preventative maintenance schedule otherwise you risk further damage to your grinder.

Changing dose times
Baristas can find it difficult to understand the correlation between changing the dose versus grind adjustment. If you adjust the grind setting (to be coarser or finer), you have to adjust your dose time. As the particle size changes, so will the dose volume.

A better way to understand this is to take the rocks versus sand analogy. If you have two buckets and pour rocks (coarse coffee) into one bucket for five seconds while pouring sand (fine coffee) into the other for five seconds, your volumes will be different – your rocks will have a higher volume.

Grind setting
The ideal grind setting is about a 25 to 30-second extraction time for 25 to 30 millilitres in cup volume. Different grinders have different adjustment dials, so start by checking your particular model and understanding which way to turn the dial to make the grind coarser or finer. When adjusting, move the dial in very small increments, approximately three millimetres, which will create a three to five second change in your shot time. Always adjust the grind when your grinder is running.

Factors that will affect how often to adjust the grinder include the age of the bean, level of humidity, light exposure, and temperature in the café.

How to adjust an electronic grinder
Based on a grind-on-demand model, follow these steps to make an adjustment:
1. Decide what adjustment (finer or coarser) you require and move the collar.
2. Using the manual dose button, discard the first 10 seconds of your grind.
3. Run a test shot, still with manual dose button, keeping dose and tamp technique consistent.
4. Assess shot quality and extraction rate.
5. Repeat steps 1 to 4, if necessary, until you have achieved correct extraction.

To adjust the dose, follow the instructions based on your brand/model of grinder.

How to adjust a doser grinder
1. Adjust grind dose to required dosage grams per click.
2. Decide what adjustment (finer or coarser) you require and move the collar to gain required grind.
3. Assess shot quality and extraction rate.
4. Adjust coarser or finer until you have achieved correct extraction.

The dose quantity will always be the same.
The coffee remaining in the chamber is off the last grind adjustment.
Never fill the doser chamber when entering a quiet period or closing down for the night.
Ground coffee will only stay fresh for 30 minutes in the chamber.

Selecting the right grinder for you is more than just looking at the latest must-have technology. Consider the above factors, the skill of your barista, and the volume of coffee you produce. After all, in terms of machinery contribution, 70 per cent of a consistent quality coffee is thanks to the grinder, 30 per cent is from the machine.

However, in the end, it all comes down to personal preference.

For more information, visit

Send this to a friend