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Question for the gauge watchers?

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  • Question for the gauge watchers?

    Let me say straight up I'm a manual kind of pourer - colour, flow, cup etc as opposed to pressure, time, volume and so on. In playing with my 6910 my first thermoblock machine after a lifetime of prosumer boilers I've read a lot and played a lot and I have a question for the gauge watchers amonst us - quite simply how do you do it?

    I read about the "sweet spot" around 9.5bar, the double wall basket and so on but on this machine I don''t see how you can get a decent extraction at that spot because there's no pressure limitation - whatever you adjust grind and tamp wise will for the most part be over ridden as the pressure will be continually variable.

    Am I right or am I missing something?

    C.

  • #2
    Originally posted by Chris View Post
    Let me say straight up I'm a manual kind of pourer - colour, flow, cup etc..
    That's ultimately all that matters.


    Originally posted by Chris View Post
    I read about the "sweet spot" around 9.5bar, the double wall basket and so on but on this machine I don''t see how you can get a decent extraction at that spot
    Personally I never believed all the discussion of the double wall basket showing 9bar - if the extraction is to occur at 9bar then that pressure has to be attained by the combination of the double wall basket along with slightly coarser than normal and stale coffee - which won't be zero impedance to water flow. Based on some discussion on the BDB thread I suspect the empty double wall basket will likely be something like ~7.5bar. If you grind to achieve a pour at that point the shot runs very fast and the result in cup is, hmm, well an experiment you'll only ever need to do once.

    Originally posted by Chris View Post
    because there's no pressure limitation - whatever you adjust grind and tamp wise will for the most part be over ridden as the pressure will be continually variable.

    Am I right or am I missing something?

    C.
    Therein lies the inherent limitation of the EM6910 (well that and the rather brutal pre-infusion - pity there's no way to turn that off), and it's probably what sets it at a slightly lower tier than I think it could be - the addition of an OPV would make a considerable improvement (I understand a couple of people have made such modifications).
    You've no idea what the actual extraction pressure is, but you can find the best extraction and note what the gauge is doing. The net result is that you'll know sooner if you mucked up dosing & grinding.
    I always found that my 6910 & taste bud combo tended to prefer a slightly tight pour of ~50ml. Pressure (by uncalibrated guesswork) maybe 12ish bar, indicated at about 2 - 2.5 hours past the empty double wall basket.

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    • #3
      Originally posted by WiredArabica View Post
      Therein lies the inherent limitation of the EM6910 (well that and the rather brutal pre-infusion - pity there's no way to turn that off), and it's probably what sets it at a slightly lower tier than I think it could be - the addition of an OPV would make a considerable improvement (I understand a couple of people have made such modifications).
      You've no idea what the actual extraction pressure is, but you can find the best extraction and note what the gauge is doing. The net result is that you'll know sooner if you mucked up dosing & grinding.
      I always found that my 6910 & taste bud combo tended to prefer a slightly tight pour of ~50ml. Pressure (by uncalibrated guesswork) maybe 12ish bar, indicated at about 2 - 2.5 hours past the empty double wall basket.
      I agree with this. Also, if you want to understand how the pressure most likely behaves you need to understand a bit about how the vibratory pump behaves in various conditions. This has been discussed in detail over on HB.

      Pete

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      • #4
        Wired - that pretty much sums up my thoughts exactly. Don't get me wrong I actually quite enjoy this machine but thought for a moment I was missing out on something but couldn't see how.

        Pete - haven't been on HB for a while - thanks for the reminder.

        C.

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        • #5
          Yeah for what it is, it's pretty hard to fault the machine really. Mine is back in service since I've had an issue with my BDB and that's in for repair.

          I'm curious as to why you'd switch from presumably a better class of boiler machines to a thermoblock though? Just after a different experience / challenge?

          Comment


          • #6
            Corrosion generally killed my Gaggia's. And when the pump went on the last one at 3pm on a Sunday afternoon the SB was the closest best option! That and for a long time I was the only coffee maker so was happy to become one with my machine and any foibles it had. Now several people with no patience want to make coffee in my absence so something that can make push button coffee but also meet my coffee curiosity was needed. It does that job pretty well I have to say.

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