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Help with uneven shot extraction

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  • Help with uneven shot extraction

    Hi All,
    I have a little lever machine, and I often find that the front half basket extracts faster than the back half... I.E. there is unextracted coffee at the back of the basket. Or sometimes, the centre of the basket is not extracted well with an outer ring of extracted coffee. I can't put more than two pulls through the puck as I just get over-extraction of what was extracted okay.
    I'm determining that with the help of a naked P/F and where I say underextracted, I mean there is black sticky coffee left on that part of the basket, surrounded by stripy/white foam where it was extracted. I can also smell that parts of the puck smell of fresh coffee, and not extracted grounds.

    What could lead to such consistant uneven extraction? I use a flat tamper and a smartgrinder. Would level/tilt of the machine make any difference?

  • #2
    Lever machines vary greatly, so the first question is what machine you are using. Then it would be useful to know whether you are using a single or double basket and how much coffee (in grams) you are dosing into that basket. Finally, whether the tamper you are using is a proper tamper that snugly fits your baskets (as opposed to those ill-fitting plastic tampers that one gets with every machine).


    • #3
      Machine is Ponte Vechio Lusso. Double basket. It comes with a nicely fitting tamper, wood handle with a lapped metal tamper. I don't measure the grams, I use the timer on the smart grinder. I have measured and reckon I have around 15 grams on average. When I tamp down there is enough space to put a think coin.
      I might get some photos of what I'm talking about.


      • #4
        Thanks. And now it is over to the Ponte Vecchio experts on this forum to answer your question. I have never touched one of these machines, though I understand they can deliver a killer shot when you get the technique downpat.

        I suggest that if you have no luck with your query here, you open another thread in the "Brewing Equipment - Midrange" section and include Ponte Vecchio Lusso in the thread title.


        • #5
          From your description it sounds as if you may be using too fine a grind, possibly due to using less than the optimum tamped (volumetric) dose for the machine.

          Work on the dose first, then adjust your grind to suit the dose.

          To work out the dose, use a cold / off machine (or machine on/hot but hasnt had water flowed through the group for some time) so that there is no wetness in the shower to stick grinds to when you lock in and remove the group handle (to see at what level the tamped dose "kisses" the shower). When you get to the point where your puk shows that it has lightly "kissed" the shower, back off ever so slightly and that is now your "working, tamped dose level" for that machine forever more. Always dose / tamp to the same level, changing only the grind to achieve best possible coffee in the cup.

          Note that as you coarsen the grind (if you need to), the dose will become volumetrically bigger (and vice versa). However, always work to the same tamped dose level that you found to be correct or most appropriate for your machine.

          The weight of the dose will then be whatever it is, for whatever beans / blend you are using, for the same tamped dose. And that is why I dont favour dosing by weight....the weight changes depending on the density of particilular coffee for a certain tamped dose.

          This can be fiddly and time consuming to work out at first but is well worth the result in the cup at the end, not to menti0n that it is a lot of fun and helps an operator to understand his equipment better.

          And of course I suggest you contact your retailer for some "how to" advice.
          Last edited by Fresh_Coffee; 29 August 2012, 09:37 AM.


          • #6
            Not sure, could be related to uneven tamp pressure though?