The Weber Key espresso grinder, in the MK2 version, is a high-end single-dosing grinder from Weber Workshops. It costs around 2,200 euros from stock in Germany! A hefty sum of money, though not entirely surprising. At Weber Workshops, their elegant BIRD French press also costs over 300 euros.
Every product from Weber is an investment, and every product we have looked at so far has been well-crafted and manufactured to a very high standard. And that also applies to the Weber Key!
And while the grinder does many things well, not everything convinced us. As you will find out in this review, we are of the opinion that the Weber Key does not perform its main task well: The taste performance during espresso preparation did not convince us.
Quality and Impression
The Weber Key Mk2 in your own coffee corner is a statement of quality, aesthetics, and willingness to invest. It looks different from other espresso grinders on the market and also sets a high bar in terms of build quality. However, it is noticeable that Weber does not communicate the exact material of the housing anywhere. At least we were not able to find this information.
Technical Data
- Dimensions: Depth 248mm x Width 109.2mm x Height 349.6mm
- Weight: 9 kg
- Power supply: 90-240V (globally compatible)
- Power: 350W max
- 83mm conical burrs by Mazzer with TiN coating
- Variable speed range of 30-150 RPM
The grinder is available in white and black, and the wooden elements can be customized.
Weber has revised the grinder compared to Model 1. Today's model has higher torque and is intended to be able to grind lighter beans without any problems. We had no issues with the grinder getting stuck, even with very light roasts.
The Magic Tumbler has also been improved, enlarged, and equipped with a different lid. However, we cannot say exactly what led to which improvements, as we have only examined the MK2 model. This test report is therefore based solely on our experience with the Weber Mk2.
Weber Key Mk2 Noise Level
The Weber Key is the quietest espresso grinder we have measured to date. We measured only 67 decibels. That is a very low value, given that many grinders are over 80 decibels.
As a rule, espresso machines are quieter than grinders. The Weber Key is one of the few grinders that is quieter than many espresso machines even when grinding beans.
retention, Speed, and Construction
In its design, the Weber Key resembles a large manual grinder. The 83mm conical burr set is driven via a central shaft. The Weber Key shares the low retention with a manual grinder. We measured a total of only 0.2 grams of absolute retention. That is truly very, very little, especially since we found no permanent retention at all. We have never experienced that before! Technically speaking, the low temporary retention of 0.2 grams is already halfway into the portafilter. It gets stuck in the Magic Tumbler: partly on the wire distribution tool and partly on the edge of the tumbler. Once again: That is almost nothing. However, it is still unattractive because these 0.2 grams sometimes fall out of the grinder at a later time and then dust the surface around the grinder.
Due to its design and the low retention, the grinder is extremely consistent and reliably outputs the amount of coffee put in from shot to shot. Thanks to the way the grinder is built, we can also quickly take it apart and clean it completely without any effort. However, the low retention makes this rarely necessary.
The Weber also shares the slow grinding speed with a manual grinder, which is of course related to the low RPM. If we put 18 grams into the grinder, it takes 25 seconds to grind the coffee completely at 90 RPM. If we fill the hopper completely and grind for 10 seconds, we get an output of 8.1 grams. This puts the grinder in the slowest category of all coffee grinders tested so far. This test is always carried out with the same espresso and set recipe.
The grinder owes its lack of heat buildup during grinding to its slow grinding speed. We measure an average temperature of 30.92 °C for five shots in a row, which we take every 20 seconds. There is therefore no risk that sensory properties will change due to the heating of the coffee grounds.
Particle Distribution and Espresso Performance
In the most important category of our test, the Weber Key shows a peculiarity that leads to a negative test result. After seasoning each grinder, we take samples for comparative particle distribution analyses. For this, we adjust each grinder to the Apas Espresso with the same recipe every time and take a sample (T4). We then set the grinder to Ristretto (T5) and Lungo (T6) and then return to the original espresso (T7). We send these samples to the Zurich University of Applied Sciences (ZHAW). The particle distribution is measured there at the Coffee Excellence Center.
In recent years, we have examined and compared over 60 grinders and correlated the particle distribution curves with our sensory perception. Before testing the particle curves, we were already puzzled by the taste of the espresso shots. We felt that our coffees, which we know very well through daily brewing, were noticeably lacking in precision. They tasted less structured, the acidity was rather unpleasant, and the balancing sweetness was missing.
This result matched the particle distribution measurements. The Weber Key delivers a very, very broad main peak of over 447 micrometers! For comparison: In the past, we have talked about a main peak starting at 320 micrometers being broad and leading to less structured cups and less clarity in the coffee.
A broad main peak means that a grinder delivers less precise grounds of a single size. With the Weber Key, we find many particles, especially in the coarse side range of the main peak. There is a distinct right flank.
This is particularly evident in comparison to other grinders we have currently measured. The Weber Key shows a particle distribution that we otherwise only know from very inexpensive espresso grinders. And no, this has nothing to do with the conical burr set. See, for example, the comparison with the Niche Zero in the chart above.
Extraction Comparison
To better understand the extraction behavior, we carried out several series of measurements. We performed extractions with the same recipe using both a medium roast (Apas, Brazil) and a lighter roast (Limontitla, Mexico) and measured the TDS. As a comparison grinder, we used a relatively inexpensive one, the Eureka Specialità.
The extractions and the strength of the Specialità were significantly higher for both coffees. Especially with the darker roast, the extraction yield was on average almost two percent higher! The TDS was 0.7% higher on average. This is possible due to the more uniform grounds of the Specialità as well as the lower number of boulders (coarse particles).
A high extraction yield is desirable for high-quality coffees!
For the lighter roast, the difference was less pronounced, but still significant. Here, too, we are talking about about 1.2% more extraction yield!
Conclusion: Who is the Weber Key MK2 the right grinder for?
The Weber Key is manufactured to a high standard. We see few reasons why the grinder should not last for several decades on a home barista bar. The low noise level also extends its range of use. As the quietest grinder measured to date, the Weber Key makes a good impression alongside very quiet machines like the Sanremo You or Maro Model 1 in offices or medical practices, as well as in households that place great value on aesthetics and high quality.
The retention is exceptionally low, and the consistency of the grinder is very good. Changing recipes is also possible without any problems, although smaller steps would be desirable. It is important that you are aware of the slow speed. The Weber Key Mk2 is one of the slowest grinders on the market!
While the importance of speed is a matter of taste, we assess the actual espresso performance of the grinder as limited. We were often disappointed by the espresso results, especially with lighter specialty coffees. The huge main peak in the particle distribution is responsible for this. We only know such a broad main peak from very inexpensive grinders. As a result, our espressos were often unharmonious in taste, less sweet, and could not keep up with the results of other, even significantly cheaper, grinders. What often led to unpleasantly dominant acidity in lighter roasts can manifest itself positively in some darker espressos. We would therefore see the Weber Key Mk2 more in the range of darker roasts. It has this in common with a grinder like the Pico from La Marzocco.
Since the Weber Key Mk2 did not convince us in terms of taste, this review also concludes on a disappointed note. High-quality workmanship and the reputation for creating great materials precede Weber Workshop. During the test of the Weber Key Mk2, these expectations were not met for us.
