When searching for the best espresso grinder to start your journey into the world of espresso, there's no getting around the Delonghi KG521. The coffee grinder is available in Switzerland for as little as 120 Swiss Francs and is offered in Germany from €140. This makes the Delonghi KG521 one of the more affordable grinders in our large espresso grinder comparison.
However, "affordable" often has its limits, and with grinders at the lower end of the price spectrum, this limit often manifests in the grind size. Many grinders advertised as espresso grinders don't grind fine enough and therefore only deserve the label "coffee grinder" and not "espresso grinder."
How does the Delonghi KG521 perform here, a grinder often considered the logical counterpart to the entry-level espresso machine Delonghi Dedica EC685? We cover this and much more in our espresso grinder test and coffee video. And of course, we also provide important tips and tricks to get the most out of your grinder.
The Limits of Grind Size
Let's not beat around the bush – or should we say – too coarse coffee powder?! The Delonghi KG521 does not grind many coffees fine enough!
What does "not fine enough" mean? A typical espresso requires a brewing time of 25 seconds. Many coffees should even be brewed longer to achieve the best possible grind.
Ultimately, we tried three different coffees and with none of them did we achieve an extraction time exceeding 19 seconds. In some cases, the coffee shot into the cup in under 15 seconds. Is that bad? Well, it certainly tastes that way. Such a short extraction time leads to a strongly emphasized, unpleasant acidity in terms of taste. In technical terms, a fast extraction is also referred to as underextraction.
And even with overdosing, we didn't get any further. A higher dosage, e.g., 19 grams of coffee instead of 18, increases resistance - but it didn't help us here. With our grind setting, we were already at the finest possible grind setting of the espresso grinder.
In other words: the Delonghi KG521 failed as an espresso grinder in its basic configuration.
Tricks, Reasons, and Possibilities
The question remains why the Delonghi KG521 is nevertheless popular among espresso beginners. There's a reason for that! The grinder is sold as a counterpart to the Delonghi Dedica EC685. We also find this small espresso machine interesting. So far, we haven't found a better, cheaper espresso machine that we can recommend for beginners.
The Delonghi Dedica EC685 comes with a double-walled pressurized portafilter basket. The basket itself creates the resistance that, with classic baskets and espresso machines, is created by the particle distribution of the coffee powder. All the espresso has to be pressed through a tiny hole in these "fake baskets."
The basic idea of these baskets is to be able to prepare bad, old, or pre-ground coffee and still build espresso crema due to the excessively high artificial pressure. These baskets do their job, but they are not suitable for brewing truly good espresso. We have dedicated a video to the upgrade of the Delonghi Dedica.
The Delonghi KG521 coffee grinder alone does not achieve an espresso grind. With the help of the double-walled basket, however, a slow extraction can be created that looks as if the espresso is well-adjusted. But this trick only works for the clock and the eye. Bad still tastes bad.
So we advise another trick. For once, it's not lowered but raised.
Tuning the Grinding Mechanism - Raising the Cone
The Delonghi Dedica is a coffee grinder with a conical burr grinder. A lower cone protrudes into an upper grinding ring. The higher the cone pushes into the ring, the finer the grind. To reduce the distance, we place a washer under the lower cone. We do not guarantee anything if you replicate this modification. Modifications are to be carried out at your own risk and may void the warranty for your espresso grinder.
First, we remove the bean hopper after the remaining beans have been ground. The Delonghi KG521 is disconnected from the power supply. The grind setting is adjusted beyond coarse - this allows the upper cone to be removed for cleaning (see grinder manual).
A cloth is placed on the cone to avoid scratching it when touching it with pliers. The grinding disc is now carefully loosened with pliers by turning it clockwise. For us, this loosening was relatively easy once we had a good grip with the pliers.
The cone is unscrewed, as is the subsequent plastic suspension and the felt washer. Below them are two thin washers, which are also removed.
For the upgrade of our grinder, we bought a third washer at a screw specialty store. (If anyone finds a link to a suitable washer online, please send it. Thanks!) A washer of the same diameter, which is a total of 1/3 thicker than the existing washers, will also work. The installed washers have an inner diameter of 10mm and an outer diameter of 13.5mm. They are so thin that our caliper could not provide an accurate result. They are approximately 0.4mm.
We put the three washers back, reassembled the other removed parts, and tested the grinder. It's important not to directly apply the finest grind setting, but to slowly work your way towards it. The grind range now shifts entirely towards finer. Going too quickly to the finest grind risks metal-on-metal rubbing and dulling the burrs.
How does the espresso taste after tuning?
It's quite astonishing: a tiny washer brings the Delonghi KG521 back into the game. The double espresso, brewed with 18 grams of finely ground coffee and 45 grams of Apas Espresso (try in Germany or Switzerland) in the cup, tasted 10 points better on our rating scale.
Retention, Speed and Consistency
The Delonghi KG521 doesn't suddenly become a good espresso grinder with tuning. But it does become an option in the entry-level espresso segment, and at a relatively low price.
Some arguments also speak in favor of the grinder. At 86.2 decibels, the KG521 belongs to the group of grinders with medium noise levels. In terms of retention, the grinder even performs well with only 1.4 grams. With a residual amount of only 0.2 grams when dosed individually and ground for over 30 seconds, the Delonghi KG521 is even suitable as a grinder for single dosing/single portions. However, with a coffee output of 17.1 grams for a 10-second grinding time, the grinder is one of the slower espresso grinders.
Regarding consistency and especially usability, a poor impression remains. Although the consistency with a standard deviation of 0.28 grams of coffee to the average dose is acceptable, it is often impossible to program the desired amount of coffee.
The dosing setting on the rotary dial on the right side of the grinder only allows for coarse adjustments in four to six-gram increments. A further "Light - Normal - Strong" scale then allows for fine-tuning in two-gram increments. With the dial set to 5, we got 22 grams of coffee in the bean hopper at the Strong setting. Normal yielded 20 grams, and Light resulted in a ground amount of 18.2 grams. If the desired amount had been 19 grams, achieving it would not have been possible with the coarse grind amount setting of this grinder.
Precision and Particle Distribution
We performed our particle distribution measurements with the grinder without tuning. On the one hand, we had not yet discovered the possibility of manipulation. On the other hand, we initially tested all grinders and espresso machines in their as-delivered state, because that is how you receive the equipment. From our perspective, customers should not be expected to go to a hardware store or specialty shop and improve a grinder with tools and non-supplied implements.
Our grinds were correspondingly coarse, and the fine particle content was correspondingly low compared to other grinders. But as stated, this was due to the grinder's limited adjustment options. Nevertheless, we were able to draw one conclusion from the particle distribution measurements.
In Test 4, we set the grinder to the finest possible grind. Test 5 was the Ristretto setting for other grinders, which was obviously not possible with the KG521. In Test 6, a Café Crème was set. In Test 7, we set the grinder to the finest grind again. We expected the grinder to precisely reproduce the same particles and a corresponding particle distribution curve. After all, we could simply set the grind slider back to 1 or the finest grind. However, the curve taught us otherwise. There was a surprisingly large difference between the two curves, which resulted in a lack of precision over several extractions.
Delonghi KG521 Coffee Grinder Conclusion
We are looking for a recommendable espresso grinder in the lowest price category. The Delonghi KG521 is not this grinder. In its factory state, the grinder does not reach the desired grind range even at the finest grind setting. The grinder grinds too coarsely. Only with an upgrade does espresso-fine grinding become possible.
Therefore, the grinder is only recommended if the home barista enjoys pulling out pliers and searching for a suitable washer. Then the Delonghi KG521 is indeed an option in the range of affordable espresso grinders.
We like that the grinder performs well as a single-dose grinder. This is a nice option for home use. The usability and adjustment of the coffee quantity are impractical, but play a minor role when used for single portions.
To all further tests and the other espresso machines in the price range of 80 - 150 Euros.
