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David Schomer’s Blog | Cutting-edge espresso technique and equipment review

Equipment Review Compak K-10 WBC grinder

Daer Reader,

The espresso machine has been largely perfected with the advent of the Synesso Cyncra and the LaMarzocco GB-5.  (Among many excellent new designs.) The fragrance of a Northern Italian roast can now be enjoyed as a flavor/aroma experience with great fidelity-at least for a few shots. What is now missing is a grinder capable of a fine cut in high volume conditions.

So, I was justifiably excited to see Compak, a Spanish company, making conical burr machines with a head speed of 300 rpm. For my test I chose the WBC (World Barista Contest) model.

The grinder turns a 68mm full conical burr at 300 rpm and grinds 17 grams in about 6 seconds. A bit fast by my standards but the first few shots offered full flavor and a thick, velvet mouthfeel which is the signature of conical burrs compared to flat burrs.  (The reason for this is the production of micro-particles in the powder produced by conical burrs.)

 

As my test continued however, the grind was a moving target, each shot reequired a finer grind than the last shot to remain within the required extraction time of about 25 seconds for a little under 2 oz. of crema.

Back on the bench the reasons became clear.

coffee trapped in dosing fins is heated by the motor

coffee trapped in dosing fins is heated by the motor

Chambered ground coffee is present in most grinder/dosers that employ the Italian dosing hopper.  The problem here is the amount and location of the coffee.  It is 10 grams. more than 1/2 a double shot dosage andit is located in the aluminum dosing chute, pictured at left and below:
This is the dosing chute empty of ground coffee.  To avoid trapped ground coffee perhaps a wider apeture into the dosing hopper or additional impeller fins.

This is the dosing chute empty of ground coffee. To avoid trapped ground coffee perhaps a wider apeture into the dosing hopper or additional impeller fins.

 

 

 

 

 

 

 

 

 

 

 

Here is the smoking gun.  Vertical alignment over the motor facilitates heat transfer through the aluminum gear assembly into the grinding head.

The tower of heat.

The tower of heat.

 

 

 

 

 

 

 

 

 

 

Direct heat transfer to the grinding head combined with 10 grams of chambered coffee baking in the dosing chute renders the Compak K-10 WBC  useless for gourmet espresso purveyors that grind by the cup.