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Thread: Decent espresso

  1. #2301
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    Quote Originally Posted by decent_espresso View Post
    Understood, and it looks like you understand the issues too. You could have made a longer profile and simply manually stopped it.



    Did you know that you can tap above and below the slider control in order to do tiny increments? If you hadn't realized that, I can see where that would be frustrating.

    Attachment 38710


    This is not something we've measured and I canít say itís been something Iíve focused on. Iíve been most interested on the temperature of the slurry. That being said, my portafilter is burning hot in the morning after my machine has preheated itself at 7 AM.

    But in general, we're going for low thermal mass so that we have more control over temperature. People have recently been doing more and more temperature profiling and thermal mass gets in the way of that. What have your temperature charts looked like?



    I'm surprised you're getting very little crema as I tend to get tons. If you would like more, I would suggest bringing your pressure up, as generally crema output is directly correlated to pressure.

    I wouldnít suggest getting your flow rate down to .5ml/s but my shots generally are between 1ml/s (start) and 2ml/s (2nd), and pretty heavy on the crema.

    The other factor affecting body is the hole size on the baskets. If you go to the larger whole baskets you should get more body because the whole size increases, and then more fines will make their way into your drink and increase the thickness.

    Also, can you post photos of your shot charts? That REALLY helps diagnose what's going on.

    -john
    Thanks for your replies John, had no idea about tap adjustments, that's a life saver for sure.

    When you say burning hot, what sort of temperatures are we talking? Would you be able to measure it? I couldn't get the group above 65degC, will double check what the PF is doing today.

    What's the reason for not recommending a 0.5ml/s flow? Looking at an Ulka flow chart it pushes around 4ml/s at 9bar and higher at lower pressures, any technical reason for suggesting 1-2ml/s or is it just best tastewise in your opinion?

    I tend to stick to a 15g VST and had no issues with crema on my L1 using it, so I'm a bit surprised. I've used a low flow profile two days ago and that only pushes the pressure up to 9bar for a few seconds, producing a hump pressure profile, so I sort of get why the crema isn't there.

    More flow / pressure curves to follow.

    T.
    Espresso: Londinium L1, ZR-71 grinder
    Photography: Flickr

  2. #2302
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    Quote Originally Posted by dsc View Post
    When you say burning hot, what sort of temperatures are we talking? Would you be able to measure it? I couldn't get the group above 65degC, will double check what the PF is doing today.
    Iím not entirely clear what you're measuring.

    Are you saying that the tablet is reporting a 65įC group had temperature? Usually this temperature should be the same as your espresso goal temperature.

    screen 2019-01-22 at 11.31.37 AM.jpg

    Note that this temperature is measured directly on the brass of the group head, so I'm fairly sure that if the tablet says that the group is at that temperature, that it is.

    IMG_9694.jpg

    Or is your concern that we are not bleeding much heat off into the portafilter? I can try to measure that, but an infrared thermometer wonít measure well off polished steel, and the contact thermometer against the bottom of the portafilter wonít measure that accurately either.

    I guess Iím not really sure this is going, since we measure each machine's temperature with a temperature probe behind the shower screen, and we get the same results that a Space gives.

    Quote Originally Posted by dsc View Post
    What's the reason for not recommending a 0.5ml/s flow? Looking at an Ulka flow chart it pushes around 4ml/s at 9bar and higher at lower pressures, any technical reason for suggesting 1-2ml/s or is it just best tastewise in your opinion?
    Purely taste. Beyond 3 mL per second I find the extraction to be quite sour. Below 1 L per second the TDS is so high that it's quite hard to drink straight. However, for milky drinks or Americano, high TDS in your initial espresso is no problem. For Rao, he prefers around 2.5 ml/s and longer extractions, usually 3:1.

    But if your goal is to imitate a slow lever shot and to get a thick mouth feel, you definitely will want a high TDS, which you should be able to produce with a higher pressure and slower output flow rate. Personally, I'd aim for 10 bar, and a 40 to 50 second total extraction time, 2:1 ratio, to get a very thick shot.

    Quote Originally Posted by dsc View Post
    I tend to stick to a 15g VST and had no issues with crema on my L1 using it, so I'm a bit surprised. I've used a low flow profile two days ago and that only pushes the pressure up to 9bar for a few seconds, producing a hump pressure profile, so I sort of get why the crema isn't there.
    Definitely, if you're using the same basket on both, you should be able to produce similar results. Perhaps try a simple pressure profile that then more closely mimics traditional espresso.

    And photos of the tablet charts always help (nudge, nudge).

    Ė John

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    Quote Originally Posted by dsc View Post
    When you say burning hot, what sort of temperatures are we talking? Would you be able to measure it? I couldn't get the group above 65degC, will double check what the PF is
    I gave this a little bit more thought, and I think the issue is that our design goals are different from what you are expecting. Most espresso machines go for high thermal mass for temperature stability. We aim for low thermal mass for faster control.

    Our goal is having a stable temperature at the slurry, and we see the mass of the portafilter as being the enemy. Thus, we directly heat the water path but then we use both fiberglass and rubber to isolate the impact of the portafilter on the infusion temperature. Here's a photograph of the group head, cover and insulation off:

    IMG_9693.jpg

    The cartridge heater in the center of that brass is heating the entire brast section to the espresso goal temperature. Water arrives in via the brown colored tube and exits via the black colored tube.

    This entire brass section is thermally isolated from the aluminum group head with a black colored fiberglass board. We are aiming to not heat the group head parts that are unrelated to the water path.

    Only the aluminum group had has physical contact with the portafilter. Thus, it's natural that the portafilter wouldn't get burning hot since it's thermally isolated.

    Besides the benefit of not wasting electricity heating things that are likely to burn you (group head, portafilter) this low thermal mass allows us to quickly change the water temperature in response to what we sense is the slurry temperature.

    If you do a quick (five seconds) FLUSH and then towel dry, before dosing your portafilter, you should have sufficiently preheated the coffee contact points. The room temperature grounds will continue to have a cooling effect on the slurry, which we will try to compensate for automatically with variable water temperature.

    Keep in mind also that the portafilter is barely in contact with the basket, so the heat mass of those two should not be interacting too much, hopefully.

    -john

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    Default Mea culpa

    All v1.0 espresso machine owners are entitled to an update kit with parts that we improved over our 1st year. In this video you'll learn what we got wrong with our v1.0 espresso machines and how we are upgrading those owners with better stuff.



  5. #2305
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    Quote Originally Posted by decent_espresso View Post
    Iím not entirely clear what you're measuring.

    Are you saying that the tablet is reporting a 65įC group had temperature? Usually this temperature should be the same as your espresso goal temperature.

    screen 2019-01-22 at 11.31.37 AM.jpg

    Note that this temperature is measured directly on the brass of the group head, so I'm fairly sure that if the tablet says that the group is at that temperature, that it is.

    IMG_9694.jpg

    Or is your concern that we are not bleeding much heat off into the portafilter? I can try to measure that, but an infrared thermometer wonít measure well off polished steel, and the contact thermometer against the bottom of the portafilter wonít measure that accurately either.

    I guess Iím not really sure this is going, since we measure each machine's temperature with a temperature probe behind the shower screen, and we get the same results that a Space gives.



    Purely taste. Beyond 3 mL per second I find the extraction to be quite sour. Below 1 L per second the TDS is so high that it's quite hard to drink straight. However, for milky drinks or Americano, high TDS in your initial espresso is no problem. For Rao, he prefers around 2.5 ml/s and longer extractions, usually 3:1.

    But if your goal is to imitate a slow lever shot and to get a thick mouth feel, you definitely will want a high TDS, which you should be able to produce with a higher pressure and slower output flow rate. Personally, I'd aim for 10 bar, and a 40 to 50 second total extraction time, 2:1 ratio, to get a very thick shot.



    Definitely, if you're using the same basket on both, you should be able to produce similar results. Perhaps try a simple pressure profile that then more closely mimics traditional espresso.

    And photos of the tablet charts always help (nudge, nudge).

    Ė John
    I've got a pad thermocouple which I've stuck to the bottom side of the grouphead using Kapton tape, see attachment.

    I agree that an IR thermometer would just bounce off the shiny PF surface and it doesn't really work well on the group either (I've got one with three different levels of EMS for different type of materials and the closest reading I got from it was still 10degC off what the TC was reading).

    The basket won't heat up much indeed as the contact surface is very small, but it eventually gets uber hot on standard machines. On DE I was worried that it might bring the brew temps down, but I still haven't tested this yet (planning to stick a TC under the basket and measure stream temps).

    I've done a quick profile with a fast flow preinfusion and a slow decline from 9bar. It did overshoot quite a bit on pressure and wasn't very stable temp wise but it was the first shot of the day and the flow was low which makes it harder for temp control. EY on this shot was 23% but the bean I'm using isn't so great so tastewise it wasn't very delicious. Will post curves as soon as I figure out how to share single photos from google albums.

    T.
    Espresso: Londinium L1, ZR-71 grinder
    Photography: Flickr

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