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Shows the position of the grinder adjusting wheel/knob

How to find the right grind for your coffee machine Part 2 – When to adjust and problems to avoid

In this second part of our two-part series on how to find the right grind for your coffee machine – we’re addressing real scenarios to help guide you through. The previous article, part 1 of how to find the right grind for your coffee machine series, detailed the grinders functions and adjustments. It also covered the correlation between espresso and the ground coffee particle size. This post covers when & how to adjust your grinder and problems to avoid.

CAUTION! Ensure you read part 1 & part 2 posts before grinding any coffee. Especially if you’ve never used a grinder before.

Setting the right grind.

Standard espresso extraction recipe

Our definition of espresso gave you the following parameters to work with:-

Finely ground coffee dose = 7-9 gms

Water temperature = 90-97 deg. C

Water pressure = 9 bar

Extraction time = 25-30 sec’s

Extracted espresso coffee volume = 25-30ml

It’s important to adjust your grinder when any of the espresso brewing parameters are under or over exceeded.

Note: Today you’ll find espresso extraction recipes on packets of coffee. They vary depending on the brand and coffee. These may make you feel a little intimidated. At this stage, avoid stressing over them, as many people find them subjective.

I would strongly recommend you keep things real and simple, especially at the beginning. Otherwise, you’ll end up stressing over constant minute adjustments in order to set the right grind for ever changing recipes. As a result, you’ll end up wasting half the packet of coffee to achieve each recipe. I’m not against varying espresso extraction recipes, but half a gram or a couple of  seconds either way is difficult for most people to taste.

By keeping things simple and consistent, you’re getting a fair representation of all the different coffees you try. And this will allow you to understand the different flavours they offer. Once, you’re comfortable and feel like experimenting with your ground coffee dose or espresso volume, then by all means do so.

Visual guides – the Crema & coffee flow

Crema floating on top of the espresso coffee as a result of the right grind during extraction. The various patterns and shades of honey/mahogany are shown.

Perfect Espresso

Coffee flowing into cups on coffee machine showing the perfect flow. Once you set the right grind, the coffee flow will be smooth and continuous as in the photo.

Perfect Flow

The crema by default should be honey/mahogany

coloured. It may also appear to have some irregular dark brown spots & stripes on it.

In addition the crema should hold for a couple of minutes and not

dissipate quickly.

 

 

The crema & the extraction flow are your most obvious visual guides in preparing the perfect espresso.

It’s important to look and memorize how each of your coffees extraction rates flow. With a little experience, you’ll know as soon as you see the first drop, that you’ve set the right grind. Bravo! Or, that you’ll need to make an adjustment.

How to adjust your grinder

A finer grind adjustment slows the flow rate. A coarser grind adjustment speeds up the flow rate.
In order to set the right grind, refer to our standard espresso recipe. If your coffee extraction flow is a fair way off this recipe, then you will need to adjust your grinder accordingly. For example, if the extraction flow is too fast, then you’ll need to adjust your grinder towards the finer setting.
Alternatively if the extraction flow is too slow, then you’ll need to adjust your grinder towards the coarser setting.
With any adjustment of the grinder, it’s important to ensure that the grinder is not running.
As explained earlier on, there’s two types of adjusting designs. The stepped and infinite.

1. The stepped adjusting wheel.

Hand pressing down locking pin on a grinders stepped adjusting wheel to release the wheel and set the right grind.

Stepped adjustment

Press down the locking pin on the collar. Adjust the setting no more than two notches and test the extraction rate.

Ensure the locking pin clicks into the new position before turning on the grinder. Readjust if needed.

 

2. The infinite adjusting wheel/knob.

Hand turning infinite adjusting knob.

Infinite Adjustment

Turn the adjusting knob/wheel in the desired direction around 2 mm max.

Test the extraction rate. Readjust if needed.

 

 

 

Problems to avoid

Earlier on we touched on the gap between the grinding blades. We also covered how the coffee travels through this gap. So, the coffee blades (providing there’s coffee beans in the hopper) will always have ground coffee wedged between them.
Don’t assume when you stop grinding that the grinder blades are free of coffee.
Extreme caution must be taken when a finer grind adjustment is required.
For two reasons:-
  1. To prevent locking up the blades.
  2. To avoid making the blades touch each other (metal to metal).
So, it’s important ESPECIALLY when you’re adjusting your grinder in the finer direction that you adjust it in very tiny increments. Otherwise you can lock up the blades. Remember adjusting finer reduces the gap between the blades. So, what your actually doing is similar to tightening a nut. You’re squeezing the retained coffee between the blades.

 

The golden rule before adjusting your grinder.

If you’re new to grinding coffee and a coffee you’ve made is a little out of the parameters, don’t jump in and adjust your grinder. Make three coffees to ensure that none of the other variables came into play. For example your tamping pressure and the ground coffee dose.
Isolating variables will help you in finding the right grind.

Using your grinder for the first time

If your seller hasn’t offered to prime and settle in your grinder, you’ll need to do it yourself. Refer to our post How to adjust a new coffee grinder.
It’s very important that settle the grinding blades and prime your grinder before making any coffee!
I know you’re now excited, but it’s important to finish reading this post before attempting to find the right grind.
If you feel this is all too much for you, then we encourage you to book our Barista Training course and bring your grinder along.

How to stop going around in circles looking for the right grind.

By keeping all variables constant will take out the frustration and help you in adjusting your grind particle size.

Most coffee machines are preset with the water temperature and pressure. In saying that, there are now coffee machines that allow the user to vary the water temperature. There’s also a few that offer variable water extraction pressure options.

Caution!

Most coffee grinders tend to retain a small amount of ground coffee within the grinding discs housing. To avoid over correcting your grind setting, it’s important to remove the retained coffee (which is at the previous setting). So, firstly adjust the grinder collar/knob. Then grind a small amount of coffee (say enough for one coffee, approx. 9 grams) and discard.

So now, the coffee retained in the grinding disc collar is the new adjusted particle size. Hence now, when you grind coffee, what comes out represents the new grind setting particle size. If you forget to follow this step, the ground coffee that will come out will be from the previous ground particle size. And, as a result will give you an inaccurate indication of your flow rate. You’ll be overcorrecting. What this means is that your jumping one step ahead in your adjustments and you’ll get frustrated.
Place the discarded ground coffee in a container to be used for priming after back flushing your coffee machine. Please respect the number of people along the coffee production chain and our environment and remember ‘Tomorrow Matters’ – ‘Aim to sustain’ – ” Do not throw away coffee!”
Caution: ensure you firstly set the grind texture and then grind and discard around 9 gms of coffee. And then grind coffee for testing.

When and which way to adjust your grinder

Now, let’s look at this scenario. You’ve just purchased the perfect espresso blend. You grind it and it runs so fast there’s no ‘crema’ on your espresso. What does this mean? It’s time to adjust.

Your grinder should be adjusted only when you see that the extraction rate is way below 18 seconds and above 40 seconds for a 30 ml espresso shot.

A woman drinking her well made coffee. She's in her own world of satisfaction.

Coffee Lover

So, unless you see that the coffee you’ve just made is way out of the standard parameters, please take the time to drink the coffee and decide if you like it. I insist on keeping coffee real, avoid wasting coffee.
What I’m trying to explain is that coffee itself has variables. So, don’t assume that if your espresso shot was 2 seconds off the recipe, that it’s not acceptable. You’ll be amazed at how flavoursome many coffees are even if they’re a little off target. And you’ll be the judge of that. So, relax, pull a shot and enjoy.
Time the extraction rate as soon as you press the brewing button. (not when the actual coffee starts dripping).
Any grinder adjustments are for the sole purpose of improving the flavour of your espresso.

Scenario 1.

Coffee being extracted with a very coarse grind setting. It shows how wavy the coffee flow is pouring and there's hardly any crema on the espresso.

Flow too fast

Let’s say you’ve made an espresso and it took 12 seconds to extract around 30 mls and the the crema is a touch pale and dissipates quickly. In this case, I would adjust my grinder in the finer direction around 2mm on a infinite grinder and 1-2  notches max. on a stepped grinder.

I would then run the grinder for around 8 seconds to remove the retained coffee in the grinders housing which is still at the previous grind setting. Discard this coffee in a container. Then, grind coffee and retest.
Repeat until you set the right grind.
If the new grind you’ve tested is close to our standard parameters, don’t readjust your grinder. Make at least another two coffees and if the results are the same, then make a tiny adjustment. Remember to keep your ground coffee dose constant.
A good idea, would be to taste all coffees. Hence, grasp a feel for the importance of the right grind setting.

Senario 2.

Showing espresso flowing very slow and as a result the a thin stream of coffee flows.

Flow too slow

Let’s say you’ve made an espresso and it took 45 seconds to extract around 30 mls and the the crema is dark. What this means is that the grind is too fine. In this case, adjust your grinder in the coarser direction around 2mm on a infinite grinder and 1-2 notches on a stepped grinder.

Then run the grinder for around 8 seconds to remove the retained coffee in the grinders housing which is still at the previous grind setting. Discard this coffee in a container. Then, grind coffee and retest. Repeat until you set the right grind.
Depending on the direction you turn the adjusting wheel, you’re increasing or decreasing the distance between the blades. By increasing this gap you’re making the coffee coarser which will speed up the flow rate. Alternatively by decreasing the gap you’re making the coffee grind finer which will slow down the flow rate.

Your now ready to set the right grind with your grinder.

We’ve seen that in order to make great espresso coffee there are many variables that need to be controlled. Once that’s done we perfect our extraction by adjusting the ground coffee particle size. So use the tips and pointers in this guide to nail your grind and help you make great coffee day in day out.
NOTE: If your grinder is brand new it’s important that you read our step by step post – How to adjust a new coffee grinder, to prevent any damage to the blades.
If you are still having difficulty with your grind, contact us to arrange a spot in our Barista Training Course.
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