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Thread: Decent espresso

  1. #1021
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    Quote Originally Posted by bachamp View Post
    I had the same thought and even talked about how we might even be able to calculate the rate of extraction if we could measure it accurately enough.
    But then realised that the volume in the portafilter will always be consistent, so any solids extracted will be replaced by water. So "ml in" = "ml out", just that "ml in" is just hot water, and "ml out" is espresso. There will be a slight difference in "g in" compared to "g out" due to density difference, but it's not going to be much.
    Scott Rao, in our internal conversation, had the same thought. It's not clear that it's impossible yet, but it's not going to be easy.

    Besides needing very accurate flow measurements (we're talking about a 4g difference here, assuming 20% extraction of a 20g puck) we simply don't know how the water-carrying-capacity of a coffee puck works. Water pockets might be forming, or collapsing, during extraction. Mostly-cellulose-remaining coffee grinds might hold more (or less) water as measured by remaining coffee material.

    However, Ray has a physics-model calculation of "puck resistance" that takes both flow and pressure into account, and we do plan on giving that number to the user in a future version, as well as charting it in real time.

    If this number is accurate, it will give us insight into % of erosion at any point in the shot, which is another way of thinking about extraction percent.
    Last edited by decent_espresso; 3 Days Ago at 04:44.

  2. #1022
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    Default the build schedule

    Quote Originally Posted by roastini View Post
    Have the ceramics arrived? Have the sheet metal parts been ordered? In the chain of dependencies for the supply line for parts, what is the chain that extends out the furthest, and what is the current best estimate of a date for the end of that chain? My real question is: Is there a fairly solid target date for assembly at this point, and if so what is it? If not, what are the unknowns that prevent a solid target date? (To be clear, I'm not trying to cast blame or anything like that, I'm just in search of data re when a DE1+ ordered from the original batch of 300 might arrive, in the US. If it matters, I'm in the 50% down payment group.)
    The ceramics were ordered a while ago, and were supposed to arrive this past week. They're "in the mail", is what we've been told, and should arrive this week.

    We haven't ordered the drip tray cover yet, because we found too much variability on the drip tray, and wanted to wait until the real McCoy showed up and we could see what we were really dealing with. Since it's a cast piece, it will take 30 days for the cast, and 35 days then for delivery. This makes it one of the very last pieces we're expecting (end of November) but the good news is that it does not delay the rest of assembly.

    Bear in mind that currently, it takes us about 30 man hours to build one DE1. With 8 people here, even if they're all working on it full time, that would be 10 machines shipping per week, hence 30 weeks. Obviously, we're going to hire people to help, but keep in mind that assembly will take time too. And, totally assembly time will be less than 30h, since we'll be making things in batches. A lot of the v4 chassis changes were to simply assembly and reduce disassembly/repair time.

    The heaters are being ordered next week, and are to take 30 days. They're the most important part, because they go in the center of the machine, and if we don't have them, they prevent the rest of the machine from being built. We were not happy to find a 15% defect rate in the 40 samples we had ordered from our supplier, and so we have switched to a heater manufacturer recommended to us by ODE. As ODE has been exclusively in the espresso parts business for decades, we tend to follow their advice. We tested their heaters for the first time in our v3 machine and they look good.

    The all-metal chassis has not yet been ordered, as we are waiting for the v4 chassis to be CNCed and arrive here for final testing. That will be ordered in mid-October, and there is a 30 day lead time on that. There were 38 changes from v3 to v4, none of them "risky" but they do need to be seen & tested before we build 300 machines. For example, we added 5mm to the depth of the DE1, because we found that once it was fully assembled, the fit was too tight to remove the low-voltage PCB for repair purposes (a fan got in the way). You had to remove the pumps to remove the PCBs and that would annoy the heck out of a repair person.

    So... to succinctly answer your question, parts will start arriving early November, and we'll start by first quality-control testing each part. Then, we'll put together the sub assemblies that we can, as the parts arrive. Ideally, the chassis will arrive mid-November and the sub-assemblies will slide right in.

    The biggest worry I have at the moment for schedule slippage is the mixing chamber, which is by far the most sophisticated part in the machine, is CNCed from a somewhat exotic material (Ultem) and requires two suppliers (CNC and custom valves) to work together. That's supposed to arrive between 7 to 9 weeks from now.

    And of course, the other concern is that Christmas is arriving, and as a relatively small company, our orders might get bumped in our supplier's schedule, to make space for "more important" clients.

    The 110V "early access" machines already sold will go out first, while we wait for the testing lab to certify our "final release" and 220V machines. We expect the testing to take 2 months.

    Nonetheless, we're very close to the end of this journey, and espresso machines will soon be shipping.

    And the good news is that once we know how to build 300 machines, we'll be in a good position to build the next 1000 machines at a much faster rate.
    Last edited by decent_espresso; 3 Days Ago at 04:38.

  3. #1023
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    Default A "Stop Espresso at This Weight" feature has been added and now works on the DE1+.

    If you buy a DE1+ and as well as our Bluetooth "Skale 2", you will be able to do "gravimetric" shots like you can on the Black Eagle and La Marzocco Linea PB.

    A new feature will appear in the DE1+ profile editor, letting you set "stop at weight", if you have a Skale. The feature won't appear otherwise.

    The DE1+ will automatically stop making espresso when 97% of that weight is reached. That last 3% is to account for the pressure remaining in the coffee basket, which will still cause some coffee to flow into your cup for a few seconds even after the pump has turned off.

    In a few weeks, I'll make the feature a bit more pretty in the Tablet GUI. Not to worry: I know it looks a bit cramped in there now.

    The "Skale 2" is a good quality scale, but not meant for use in wet environments, which is why we're working on our own "Decent Scale". However, in the interest of not delaying the use of this useful feature, I've implemented it with the Skale so you can get started using it right away. Eventually, we'll have our own Decent Scale and this feature will work with that too.

    grav2.jpg grav3b.jpg
    Last edited by decent_espresso; 1 Day Ago at 05:23.

  4. #1024
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    Default Flat UI be gone

    A few weeks ago, the Nielsen Norman Group published a study indicating: "The popularity of flat design in digital interfaces has coincided with a scarcity of signifiers. Many modern UIs have ripped out the perceptible cues that users rely on to understand what is clickable." https://www.nngroup.com/articles/flat-ui-less-attention-cause-uncertainty/

    I found the study very convincing, as I've found my iPhone harder to use since they've made all the UI elements "flat".

    In early September, I changed the Decent Espresso web site's "CSS Theme" to use drop shadows on the buttons (previously, buttons were "flat"). I sat back and waited for the complaints to roll in. They didn't, and the "how do I buy something on your website?" tech support messages seemed less frequent.

    On our espresso GUI, I've often found it a bit hard for the to track "what should I do next" ?

    Today, I've taken the Nielsen Norman Group advice to heart on our espresso machine tablet software, and all "tappable" buttons and tappable icons have a 3D "lift" to them. I'm hoping this makes it a bit easier for baristas to intuit what to tap on.

    Below are some animations showing the DE1+ gui and also all the configuration pages. FYI I use photoshop to make the tablet GUI, and its animation feature to test what common commands might look like to the user.

    ---

    And for a walk down history lane...

    I'm a big fan of Jakob Nielsen, whose "Green and Blue" usability book as a huge early influence on me in my 20s. My employees grew so annoyed at this book that, in jest, they had a "What Would Jakob Do?" t-shirt and mouse pad custom made as a gift to me.

    Jakob had very kind things to say about the Lyris Email List Server software I wrote (he used it, back in the deay) and he even studied how usability increased his newsletter subscriber size: https://www.nngroup.com/articles/mai...ist-usability/ - a very tangible proof of usability making business sense.


  5. #1025
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    I think flat designs with no '3d' indicators of buttons likely follow public adoption of smartphones and touch screens. As we learn to operate the OS of the main players their decisions on where design elements should go become ingrained in our muscle memory - so we know where the 'next' button or 'close' button should be. Once this is learned these flat designs likely work fairly well, but if you are a very infrequent user perhaps they make things harder to learn.

    I have to say I am often a bit befuddled by how long it takes friends/family to work their way through a new UI on a different device - something which to me feels like it is obvious. Perhaps this is down to having used tach and different UI's day in day out for most of my life.

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    Quote Originally Posted by decent_espresso View Post
    letting you set "stop at weight", if you have a Skale.
    I am still a little bit puzzled in regards to gravimetric shots.
    Shouldn't measuring the flow rate be enough? After all, [time/s] * [flow mL/s] = mL (1g = 1mL when we ignore the coffee solids)

    As for UIs: Hardware designers should never do UI design. I want my OS X 10.6 back.

  7. #1027
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    Quote Originally Posted by patrickff View Post
    I am still a little bit puzzled in regards to gravimetric shots.
    Shouldn't measuring the flow rate be enough? After all, [time/s] * [flow mL/s] = mL (1g = 1mL when we ignore the coffee solids)
    • If your scale is more accurate than your flow meter, gravimetric is better at getting the desired amount of liquid in the cup.
    • If your puck continues to absorb some water after the pressure rise that indicates the end of preinfusion, gravimetric is more accurate.


    The flow meter counts revolutions of the meter, which is a proxy for volume of water in. And because there is no guarantee that the puck is 100% perfectly saturated at the beginning of the shot (after pre-infusion), volume of water in is a proxy for volume of water out.

    An accurate, properly tared scale is a far more direct measurement of espresso in the cup. So if that's what you want to measure, gravimetric control will get you far better results than the indirect measurement from the flow meter.

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