A Blade Grinder for Great Espresso

Robert McKeon Aloe
Nov 15, 2019 · 7 min read

I know what you’re thinking, “How dare you even suggest using a blade grinder for espresso!” The caveat is a Kruve sifter. So, if you are a purest, read on because I’m actually aiming to challenge conventional wisdom due to technological advancements.

Theory: grinder type or quality is not important anymore due to sifting technology, particularly when pulling a staccato espresso shot.

As with any theory, I will lay out the argument and then discuss my experiment.

Grinders

There are burr grinders and blade grinders. Blade grinders are not suitable for espresso, or at least that’s what every barista will tell you. Every now and again, someone will show that if someone is in a pinch, you might be able to get decent espresso with a blade grinder, but consistency is a problem.

Blade grinders function by whirling a blade around and chop the beans to pieces. This leads to large chunks, and the particle size isn’t too consistent. Blade grinders are good for brewing coffee in ways that don’t need fine grounds like French press or drip.

https://www.coffeedetective.com/burr-coffee-grinder.html

Burr grinders progressively grind down the beans with really good consistency. They give the same distribution of grounds every time. This is really important for espresso, so any good barista will use a burr grinder.

Burr grinders, https://www.home-barista.com/repairs/bunn-lpg-bulk-grinder-rebuild-t14252.html

Burr grinders come in two types: conical and flat. I’m not quite sure if one is better than another, but per this conversation, it is irrelevant.

Blade grinders have some deficiencies particularly in particle size. There was a video by James Hoffmann where he discussed hacks to make a blade grinder work, but the caveat was that this technique wouldn’t be consistent and difficult to judge for the sake of trying to dial in a grind.

Sifting: Staccato Espresso

In early 2019, I was interested in trying the Kruve sifter. I wasn’t convinced it would help improve my espresso, but I was more interested in experimentation. I was more afraid that it would help, and I would be stuck with another step in my tedious espresso ritual. I was correct that it would length my ritual, but I underestimated the value it brought to the espresso experience.

After a week of playing around with it, I had determined that an espresso shot was improved using two or more layers of sifted coffee. At first, it was just two, but then I experimented with more. I settled on 3 layers for a time, and in the past two months, I’ve switched to 4 to 5 layers.

The layering also did not throw out any particular particle size. I found the larger particles could stay in their layer, and the superfine were good in a different layer. The order was fine on bottom, coarse in the middle, and mid-range on top. To dial in a grind, one would adjust the layers but not the grinder.

And so, the staccato espresso shot was born.

The results were out of this world. I have not seen any data contradicting the claim. I used both subjective scores (an average of 7 taste scores) and objective metrics like TDS (Total Dissolved Solids). I have collected a lot of data towards this end, but the shot preparation takes more time.

The technology isn’t there to make this method commercially available, and it would require a good bit of training and experience for a barista to repeat the preparation consistently. One day, I hope someone develops this technology, and maybe it should be me. I’m not sure what the future holds.

Buying a Grinder?

I’ve been considering buying a new grinder for the past two months. I have a manual ROK grinder and an automatic Lume grinder, but I don’t feel like manually grinding any more nor do I want to hit the button every two minutes to get enough coffee from the Lume grinders. I like the grind profiles from both though.

So, what should I buy? Grinders range from $10 to $5,000 (probably more but I haven’t see one). The main issue is that I sift my coffee grounds, so would I benefit from a $4,500 single dose, retentionless grinder? How would I know what level of quality is required to maintain good staccato shots?

To answer this question, I wanted to fail fast first. I wanted to use the very worst grinder imaginable because if sifting worked to make a good espresso shot from the worst grinder, then sifting would work for everything in between.

Design of Experiment

First, I borrowed a blade grinder. Initially, I thought I would use a large sieve to catch the larger pieces requiring more grinding, but I decided to use my usual sieves: 400um and 500um. The plan was to grind, sift, and see how much was at the finest level. I would aim for a 4:5:6 ratio (fine:mid:coarse) as that is my starting point for the layers in a staccato shot. Then I would re-grind.

I started with 31 grams of coffee. I expected to lose almost 1g from the sifter and the grinder, and I wanted to be left with 2 shots worth of coffee at 15g each. Using 4g of fine grounds meant sifting until I hit 8g in the bottom sieve.

I had to grind four times to do this, and each time, I ground for a bit longer. The issue with a blade grinder is that the superfine particles get stuck on top, and the fine particles end up below the blade. So, it requires some care. It is more time consuming than a burr grinder, so quite impractical except for an experiment like this.

Ultimately, I ended up with a good grind because of the sifter. As one can see below, the fine, coarse, and mid particles look consistent.

Here is a post-tamp shot for blade vs burr, and they look similar. Of course, looks can always be deceiving, so one should not judge on this but the actual results in the cup.

I pulled a regular shot and one staccato shot with the burr grinder, and then I pulled two staccato shots with the blade grinder. The first blade shot was slightly uneven on the tamp, but still came out very similar to the burr. The second blade shot came out more even and had similar taste and TDS numbers.

Experimental Constants:

  • Beans roasted on 10/31/2019, Congo Umoja Wetu/ Nicaragua Acopio Suyatal
  • Brewed on 11/10/2019
  • Espresso Machine: Kim Express
  • Bottomless Portafilter
  • VST 7g basket, overfilled to between 14g and 16g
  • Pre-infusion: 15 seconds
  • Bloom: 15 seconds
  • Infusion: 30 seconds, pressure pulsing
  • Pulled the first shot near a 1:1 ratio using measuring espresso glass, and let the rest into a separate cup.

Below is a chart of my scores plus coffee extracted for the shot I prefer (1:1 ratio) and the seconds (which if added to the first shot would make a 3:1 ratio shot). The first blade shot was not as well evenly tamped as the second one.

Summary of Results

The blade staccato shots were similar to the burr staccato shots between the subjective taste scores and the amount of coffee extracted. Both were a cut above a regular shot for subjective scores, and they both had a larger amount of extracts in the first bit of coffee than a regular shot.

Conclusion

Trust me, I’m not going to buy a blade grinder or start using one to make espresso. The goal of this experiment was to understand how the quality of my grinder impacted my shots considering I was pulling staccato shots. My experiment shows that the grinder quality is much less important to the quality of the shot than I previously thought.

Now, other factors like time and consistency would suggest using a burr grinder, and better burr grinders would improve on those aspects. However, I don’t think a $4,000 grinder or even a $1,000 grinder would be worth it for me. Oddly enough, if you make a coffee sifter that was automatic, it would probably be close to $500, so as technology progresses, one would still pay the same, but the quality of the espresso would go improve.

Overthinking Life

Thinking too much on Philosophy, Math, Science, Politics…

Medium is an open platform where 170 million readers come to find insightful and dynamic thinking. Here, expert and undiscovered voices alike dive into the heart of any topic and bring new ideas to the surface. Learn more

Follow the writers, publications, and topics that matter to you, and you’ll see them on your homepage and in your inbox. Explore

If you have a story to tell, knowledge to share, or a perspective to offer — welcome home. It’s easy and free to post your thinking on any topic. Write on Medium

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store