Background
I am a field service engineer who likes to drink espresso. I travel quite often, I have completed 22 international trips this year and I have one more trip to complete before Christmas. Sometimes I travel to places where good (sometimes average) espresso is readily available (places like Ethiopia, Kenya, Tanzania, Algeria and Morocco). But I also travel to places where the only option is to make your own coffee. Until now I just made french press in the hotel room.

I use an Arrarex Caravel and Faema Baby Faemina at home and use Eureka Mignon and MadebyKnock Feldwood grinders. I have taken the Baby Faemina and Feldwood with me on a few trips but because I take so many tools and instruments with me it is not always possible to take the rather bulky machine with. So in short, I like espresso and I can tell the difference between good and average espresso, but I am not a connoisseur or cup taster.

I order bicycle parts from Bike24 in Germany from time to time, and when I saw that they have the Cafflano Kompresso in stock it went straight to my basket.

Device capability
I initially had my doubts about this device, regarding the force required to achieve the correct pressure for espresso extraction. I did a few calculations and a non-scientific test and I quickly realised this device can theoretically make real espresso. There was a thread about this device which is now locked where some people claimed that is is impossible to achieve 9 bar pressure, but from my calculations it's possible.

The diameter of the cylinder is 28mm. From this it is easy to calculate that you will need a force of 554,18N exerted on the piston to reach a pressure of 9bar. Now this is where some people will say things like a small Chinese woman needs to sit on the device with all her bodyweight to achieve the correct pressure

But if you take the above mentioned force and divide it by two (two hands) you get 277,09 N per hand. This is where my non-scientific test came in. I was out in the field, and took an adjustable wrench and my luggage scale. I hooked the luggage scale hook between the two jaws and supported the other end of the wrench in my base of my palm. I then pulled the scale towards my palm with three fingers (this is similar way which you will hold and pull the device). Without too much effort I pulled the scale to its maximum of 35kg. This is equal to a force of 343N. I am sure I would have reached over 40kg without over exerting my hand. I think in the locked thread many people underestimated the strength of the human hand. Ever tried to remove a biscuit from a baby's hand?

I work with my hands for a living so it's definitely possible that my hands are stronger than those of a person who clicks a mouse for a living but I am sure that most people will be able to make espresso with this device.

Results in the cup
I've only had 4 espressos from this device so far and in my opinion the results are on par with the Faema Baby Faemina. This device will not replace a real machine and it is not ideal for daily home use, but in my opinion it is a winner for traveling, especially of you are after no nonsense straight espresso shots to fire up your engine for a long day of work. The espresso it makes has good body and crema. The crema is similar to that you get on the Baby Faemina which is a little less dense than the crema I get from the Caravel. The last photo was taken about 30 seconds after completing the shot. Directly after completing the shot it's about 75% crema and then the crema reduces (like a Guinness) until it's a 10-20% layer on the top.

I managed to fill the basket with 16g of light roasted coffee and the output was 45ml when I filled the device to the 60ml mark. I think for darker traditional espresso roasts the dose will be less, probably in the 14g region.

I got one too! I saw the Kickstarter and figured it was cheap enough to take a gamble.

I use mine at work where I can get 200deg water out of the office coffee pot. I have to bring pre-ground from my home grinder, which isn't ideal, but I can make an espresso at work and that's pretty nice. Just like any espresso maker, you have to dial in your grind. The Kompresso is forgiving though. I don't mess with a scale or anything, but I have found that it helps to invert and fill with hot water first to warm it all up before using. I have been mostly making Americanos and am happy with it for this use. Of course, its no replacement for my home machine, but its great for days when I want an espresso or Americano at work.

You can check fitness sites, the various tests shows, as in this hand grip strength page below, that for a sporty adult... 50 kg seems doable

http://www.topendsports.com/testing/tests/handgrip.htm

Thank you for the post.

I was quite excited about the prospect of something closer to an espresso being produced at my desk in the office but not quite there yet (also considered the flair espresso but this was much cheaper)

Only tried the device 3-4 times so far and have to admit I haven't spent enough time dialling my grinder for this but so far I have not managed to produced anything near some of the appearance (can't comment on taste) of some shots I've seen online. Perfectly drinkable coffee and surprisingly warm (was worried about temperature) but closer to a stronger filter than an espresso. Will keep trying for a while.

I would be really surprised if one could apply more than 20 kg to those small and thin plastic handles without bending/breaking, which would be something like 3.2 bar

One of our most exquisite barista, has his machine modified for 4.75 bars, and swear this is the secret of his coffees...

So far I was using from 2-3 to about 11 bar. You can get nice coffee with lower pressure and still some crema, just that it is different than espresso made with higher pressure

vit wrote:I would be really surprised if one could apply more than 20 kg to those small and thin plastic handles without bending/breaking, which would be something like 3.2 bar

The handles are much stronger than they appear. I estimate that I apply about 25kg per hand when I use it. That equals 50kg or 490N. With a piston diameter of 28mm a force of 490N will result in approximately 795kPa or 7,95 bar.

Could be. Did you actually try putting it on the scale ?

A scale wouldn't tell the whole story. You don't just push down. You also pull up on the corresponding handles below as an additional force multiplier.
I don't know if I'm getting 9bar, but it tastes good.

Never got anything like this from an Aeropress...