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I just bought a Nuova Simonelli Musica + Eureka Mignon, so I'm practicing extracting a shot.

I usually use single shot portfilter, as I am at home, and I live alone, so I don't want to waste too much coffee.

So, I adjust grinder level, coffee quantity, and tamper.

But when I put a double shot portfilter, I must change all my settings, because coffee is to thin, and water will not go through coffee ?

Is it possible to manage both single and double shots with the same configuration ?

Otherwise, how should I manage multi configuration ???

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  • I didn't get it. Assume you set your grinder to single shot. When you fill your basket twice from Mignon and then tamp, it should work. Doesn't it work?
    – MTSan
    Aug 27, 2018 at 14:56
  • The flow depends on how much coffee you put inside filter no?
    – Juliatzin del Toro
    Aug 27, 2018 at 17:51
  • Double sprout portafilters have more/wider holes somehow. So if you use the double portafilter, given the same pressure and same amount of tamping, it should work.
    – MTSan
    Aug 27, 2018 at 17:57
  • Ok, I check it now. The main factors that affect the resistance (against pressure) in the portafilter is the thickness of the pellet (so tamping is really important), grind size, and the holes. Single/double baskets' holes are different in the sense that, when you use single basket (in most designs) you cover half of the holes at the outer circle and only the other half at the center is available for flow. Double baskets enable all holes.
    – MTSan
    Aug 27, 2018 at 18:12
  • Tomorrow morning I will try with double shot.
    – Juliatzin del Toro
    Aug 27, 2018 at 21:05

1 Answer 1

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After careful configuration, your settings should work for both occasions.

The reason to have a thin pellet (cake) when you fill your double basket with a single shot amount of grounds is, the area of the double basket is set to hold twice as much grounds of a single shot basket.

The reason behind that is the Darcy equation which defines the filtering properties based on

  • area (constant in both baskets),
  • viscosity (constant for water),
  • filtration velocity (constant, if we assume you have constant pressure),
  • filtration permeability (we'll come to that later),
  • and the thickness of the pellet (we'll come to that later).

So, non-constants in this equation are the thickness of your pellet and the filtration permeability. Let's consider permeability first. Kozeny&Carman equation defines this for porous medium. I can say, in short, reliable grind size defines this. Therefore, if you are ensured that you have homogeneously ground coffee and tamp them with equal force (say 15 kg-f), you can safely assume permeability as constant, too.

Now, the last one: thickness of the pellet. Please see the below photograph I have taken, first.

single and double spout portafilters

As you see, the single spout portafilter has less space and the water flows from a narrower set of holes to keep the thickness constant. When you fill the double spout portafilter, the water flows uniformly and the thickness will still be the same.

So, all you need to do is setting your grinder to single shot amount (7-9 grams). Then, using single or double portafilter according to your needs. When you need a single shot, fill your portafilter with a single shot amount of coffee. Filling your double portafilter with double the amount ends up a doppio or two espressos in two cups.

Enjoy!

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