qualin Senior Member Joined: 30 Jun 2012 Posts: 496 Location: Calgary, AB Expertise: I love coffee
Espresso: Izzo Alex Duetto 3 Grinder: Mazzer Mini Elect. Type A Vac Pot: Looking to buy Drip: Manual Roaster: Considering?
Posted Mon Dec 31, 2012, 4:50am Subject: Re: Challenge: Build the world's best Super automatic
Perhaps, I should probably just put forth an analogy.
Automatic and manual transmissions in cars.
When a car with a manual transmission stalls or jerks, it isn't because it is the transmissions fault, it is because of the operator. As the operator became more proficient driving the vehicle, the ride got smoother and safer.
When automatic transmissions first hit the market, they really sucked. Read about the Buick Dynaflow, for example. Or the wonderful 2-speed automatic GM put in the Bel Air. (Which drag racers today use a descendant of that transmission, surprisingly enough.)
Despite improvements in technology, even modern automatic transmissions suck in one way or another, but we put up with it because they're convenient. The 4 speed automatic in my 2003 Hyundai Elantra loves to hesitate between shifting gears at times. Going to pass someone can be aggravating because it can take two seconds for it to downshift. Sometimes it likes to downshift with a jerk. Such is life. It isn't perfect, but it beats having to ride a clutch pedal in rush hour traffic. Reviewers complain about how some automatic transmissions like to "hunt" for a gear. My Elantra does that on occasion when it is on just the right kind of hill at the right speed.
For the record, I also own a car with a manual transmission and there just isn't any comparison between the two vehicles. With the manual transmission, I have full control. I decide when I want power to the wheels. I decide which gear I'm in, which gear I'm going to shift to next and how long I want to stay in that gear. You just can't get that level of control from a manumatic or a DSG. (For arguments sake, while there is gear control with a DSG, there is absolutely zero clutch control.) Sometimes I do end up in a situation where I'm experiencing gear hunting with a manual transmission, but it is all my fault in that case. :)
The point I'm trying to make is..
Using a super-automatic removes a lot of the control from the operator. Ever seen a barista use one? They push a button and that's it. There's nothing to control, so even though they've been removed from the equation, the machine will always get it wrong because the machine can never know the exact conditions the coffee needs to be brewed in. It can only guess and make an approximation.
The barista has been reduced down to almost a button pusher instead of someone who is skilled, knowledgeable and educated on what really makes a decent coffee. Just as much as someone who knows how to drive a car with a manual transmission is also considerably more skilled than someone who only knows how to drive an automatic.
Every skilled barista I know tastes an occasional shot to see if the parameters are to their liking.. It isn't just about Input Dosage, Extraction Duration, Extraction weight and Extraction Volume. It's also about what the barista thinks is the best taste they can get out of that coffee. With a Super-Auto, all of that is removed out of the hands of the barista because all they can do is say, "It sucks" and there isn't much more they can do to fix it, short of messing around with the parameters on the machine until they get something which is somewhat drinkable.
It would take considerably more technological refinements before a super-auto could even approach that of a semi or full auto when it comes to the quality of the coffee. Super-Auto technology is still very young yet and just like automatic transmissions, it took decades before the auto manufacturers could build something that got better fuel economy than a standard transmission.
The thing you need to keep in mind is that unless you are a real serious electronics engineer, hydraulics engineer, mechanical engineer and computer programmer, you would have to break every convention in the book and design something that nobody has thought of yet that in all honesty, doesn't suck.
What a lot of people forget was that Achille Gaggia was just an ex-aircraft mechanic who figured out a way to brew espresso. His invention transformed the entire coffee world and turned it upside down. The bar has been raised much higher since. The key thing though was that Achilles looked at a previous patent, got an idea and ran with it. He didn't know anything about espresso machines either at first. :-)
So, rather than talk about it, do it. Build it and see what works and doesn't work. If large coffee equipment manufacturers haven't been getting it right, find out why, learn from it and build something like what Achilles did to turn the entire coffee world around on its ear.
I'm going to say right from the heart that if you just do what everyone else is doing, you won't get anywhere. The first place to start is find out what people are doing wrong first. Take a broken super-automatic apart. Then, find out why a semi-automatic or fully-automatic just works so much better.
If you are truly passionate about this, you will take the time to learn how everything works and fits together. Read what you can, learn what you can, then make informed decisions and run with them.
Besides, every coffee equipment manufacturer is looking for a way to make their equipment better. The Quickmill Monza is a testament to that. It is a way to stay competitive in the market. If you think you can do better, by all means, we're not stopping you. :-)
Traditional machines are using the ground coffee trapped in the portafilter as a restriction to flow. This restriction is necessary to have the hot water properly extract the flavour and oils from the grinds. Above the grounds, the water is nearly boiling and about 140PSI above atmospheric pressure. At the bottom of the portafilter the pressure is only atmospheric pressure (Of course, it's falling from the dispensor through atmosphere). This pressure drop through the grounds begets a drop in temperature, and somewhere inside that puck is the perfect extraction layer, with a thin layer of too hot above and a thin layer of too cold below. So now that you're picturing that puck as a tool in the pressure-control of the brew process, it becomes clear that trying to increase make it faster is just increasing the pressure on the top layer and narrowing the amount of sweet-spot in the middle (The bottom will always be zero above atmospheric). (Most) Superautomatics use preset checkvalves at the brew-unit outlet to induce a pressure drop AFTER the nearly boiling water has already left the puck, making the whole puck a potential "Sweet spot". The grounds are much coarser so that they won't create much of a restriction and thus a pressure drop. So, because the pressure drop over that final checkvalve can be set to determine what the rate of flow for expresso extraction COULD be, it is set low enough that the flow rate can be increased... And the label on the box can say "Bean to Cup Espresso in 9 seconds." Or actually, it will probably say "Perfect Bean to Cup Espresso in 9 seconds" because that's what consumers want to see.
Machines with pressurized portafilters are using this "Post-extraction" pressuredrop, too.
shadowsnuzzy Senior Member Joined: 8 Jan 2011 Posts: 67 Location: Pleasanton Expertise: Just starting
Posted Mon Dec 31, 2012, 6:08pm Subject: Re: Challenge: Build the world's best Super automatic
But even if the whole puck is a sweet spot, why does the espresso come out worse than a standard semi auto's espresso? What's the point it straying from the semiauto pressure model if the espresso brews faster but taste worse?
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