EEVblog #1161- Automated Coffee Machine Dumpster Teardown

[EEVblog]

Teardown Tuesday-ish random dumpster dive!
What parts can we salvage from and automated coffee machine? and how does it work?

[beanflying]

Welcome to part of my world. Repairing Coffee machines is a glorified cleaners job (@ $80-110+ /hr  ) then techie mechanical failures with pumps, valves and solenoids then electronics very occasionally as they are the reliable bit.

A lot of the fully autos are supplied 'free' as part of a coffee supply contract to offices (at inflated prices) never maintained and then get written off rather than being repaired. Good dough if you find a sucker company to take a contract for X years. This plus the lack of mechanical parts availability makes them a PITA to repair. So AVOID at all costs.

Nuts and bolts of the machine you have is water heated by thermoblock one side is a hot water outlet the other is steam for the milk. Hot Water (should be circa 92 degrees) is forced by the pump to the top of the puck which is created by the plastic section you had in your hand. The beans are ground into that mech and compressed by the wormdrive on it into a solid puck then the water forced through it (should be 9bar but it won't be). The puck is then dumped by that mech into the bin. The Limit switches and mech are to adjust the grind from fine to course by raising or lowering the grinder burrs.

As to what they produce in the cup it is not coffee even when well tuned


edit anyone wants one ( I currently have 3) $50 + freight (for suckers only) or after I have stripped them their bones are off to the tip where they belong

[helius]

This type of machine would be called "super-automated" by the industry, because it requires no operator intervention beyond adding the beans and water and pushing a button. Most espresso machines require much more handling, even those classed as automatics.

The handle in which the grounds are placed in an espresso machine is called a portafilter. The grounds are dispensed in a "dose" from the grinding machine, tamped in with a tool, and the portafilter is then attached to the "group head" of the espresso machine, which supplies hot water under pressure. It's the pressurized water forcing its way around the fine ground particles that extracts the coffee in the manner of espresso, which is less bitter and more aromatic than other forms of extraction. Just how much pressure, temperature, and volume of water is dispensed changes the quality of the drink, and it's control of those factors that gave rise to the "manual, semi-auto, and automatic" machine classes.

[Smokey]

The machine appears to be a "MEROL ME-710"

https://www.aliexpress.com/item/coffee-machine/1081252160.html

US $1,479.00 / piece!

If that was a $1500usd piece of test equipment you know you would have been treating it differently than "destructive tear-down"

[beanflying]

Super Auto would generally not have a separate steam wand as frothing of the milk is volume controlled via a venturi or second pump and dumped straight into the cup after the shot with no need to have a separate jug. Their kwality of these in the cup is even worse, Muckdonalds finally got the message and removed their big ones from service a few years ago.

The shots here are from a Super Auto. Fridge is under the adjustments for Latte and Crapuchino controls in Photo 1. Photo 2 is of the Pump section. Circa $10k when new. Replaced by an $8k one which was 'just drinkable'

What Dave puilled down would be a Semi Automatic.

[Fungus]

I think a "megnet" is what they call magnets in New Zealand.

[johnlsenchak]

The  only  thing interesting in this tear down was  the micro-controller /  power supply board


Dave is now a official  bean  counter  for the EEV Blog forum  !

[capt bullshot]

Yes, it's kind of funny to watch Dave tear down the machine.
I'm a coffee hater, I don't like it, I don't want to know how this works or what this thing does, and all the coffee power spilled on my desk 

[dardosordi]

I liked it, not because of the mandatory like, but because I like teardown of random things. I do it for fun at home, and I love watching Dave do it. Thanks!

[jnissen]

Was painful to watch! I have owned and repaired my super-automatic for years. The brew group is the real money shot of the machine. The controller and such is normally reliable and care free. That machine was not cheap. I bet they sell new for in excess of $1500 seeing how the internals looked. The did not skimp on some of the plumbing pieces and heater block connections. Impressive and Dave could have made some real money if he had refurbished and resold it. Just cleaning it and re-lubricating the o-rings is often enough.

This one pumps water only. The thermo-block is in two sections. One for hot water and the other to produce steam if using the front wand. The wand puts out steam. A missing reservoir for the milk hooks to the wand so it can mix milk with steam and produce latte's. Cleaning that milk reservoir and the plumbing is a PIA if you only use it once in a while.

[In Vacuo Veritas]

What's with the coffee hate? Is it like cilantro for some people?

[sonic]

Quite a clean layout! The guts of my last hopper thingy (Saeco brewing unit OEMed) machine while replacing the thermoblock:

[Grapsus]

Let me try to say the absolute minimum for you all coffee haters to understand how such machines came to be.

Coffee beans contain an addictive substance called caffeine.
The goal of coffee making is to extract the caffeine and other substances into water so you can taste them and put them into your body.

There are many different techniques to acheive this extraction.
All of them require the beans to be roasted and ground.
Then water must come into contact with the ground coffee.

Many of the simple methods of making coffee (like pour over) are quite slow and their yield is weak (little stuff extracted per volume of water).
At some point italians invented a better method that is fast and has a high yield: the grind is pressed into a compact puck and hot water (around 92° C) is forced through it at high pressure (around 9 bars). It's called expresso.
One dose of expresso is 8 grams of beans used to yield 25 ml of coffee in 25 seconds.

First machines were manual: the barista had to pull a lever to create the pressure and force the hot water from a boiler through the coffee.
Then automatic machines came along: the barista uses a grinder to crush the beans into a small basket (the filter) then he presses the grind into a puck with a tamper, the filter is placed into the coffee machine (it is held with a portafilter), the machine forces the water through the filter and the coffee drips into the cup, the barista removes the portafilter and discards the used coffee puck.
This process is the absoute golden standard of expresso.

The problem is that it is pretty complicated: two separate machines are required (the grinder and the coffee machine) and a lot of skill. There are many variables and things to tweak and people get pretty OCD about it (see r/coffee).
Here is a video of the whole process: https://www.youtube.com/watch?v=o3oSlZSXHog

In a typical office no one has the skill or the patience to operate a traditionnal expresso machine and this is how the super-automatics came to be. They try to automate everything with one device. They have two inputs, beans and water and two outputs, the drinks and the used coffee pucks. It sounds simple but it's actually a huge engineering challenge.

Here's everything the machine has to do successfully in order to produce drinks:
 - grind the beans into the brew unit (the grind size and the total mass of coffee should be consistent at all times)
 - the brew unit must compress the grind (ideally with a force between 7 and 15 kg)
 - water at 92 °C must be pumped at 9 bars of pressure through the whole surface of the coffee puck
 - and the trickiest part of all: the brew unit must discard all the mess, clean and dry the brew filter so that another drink can be made
hence everything you see in that machine.

[Grapsus]

Also if you want a latte (expresso mixed with frothed milk), milk must be frothed with a wand that spits steam.
As the expresso water temperature is below the boiling point of water it cannot be used for steam.
Three solutions exist for that:
 - a single boiler with two temperature settings (the user has to wait between temperature changes)
 - two separate boilers at two temperatures (like the machine in the video)
 - a big hot boiler for steam that is thermically coupled to a colder boiler for espresso, it's called heat exchanger design.

[beanflying]

It is just possible some of us treat our coffee a little TO seriously btw. 3grp commercial Manual Lever machine, Commercial grinder followed by the mess that is currently my workbench and at the other end a 1kg Coffee Roaster. Not shown is 600kg of Green Coffee beans in the shack.

Their is a Bean in my Handle for a reason and I acknowledge my problem

THEIR IS NO X IN ESPRESSO !!!!!!!!! 

[KaneTW]

600kg? Do you roast commercially? There's no way you can drink that much coffee before the beans start to lose quality.

[beanflying]

600kg? Do you roast commercially? There's no way you can drink that much coffee before the beans start to lose quality.

Only 10-20kg a week for pocket money. Beans stored in hermetic bags are fine for a year in spite of the hipsters pushing seasonal under roasted beans to their customers. Moisture ingress is one of the big issue with Greens along with reasonable temperature control. Longer term storage beans lose some high notes for sure but gain in others such as becoming more subtle and mellow. Interesting article about aged beans before roasting somewhere, will see if I can dig it up.

Edit This Japanese business has been doing it since forever https://www.perfectdailygrind.com/2016/02/cafe-de-lambre-where-green-beans-have-been-aged-for-23-years/

But recently the Hipsters and marketers have tried to jump on too. The truth is it works for some beans but not others.

[KaneTW]

20kg a week would do it. I'm storing my beans for roughly a year, unsealed, and go through 20-25kg yearly.

[Grapsus]

THEIR IS NO X IN ESPRESSO !!!!!!!!! 

My bad, you're right, it's written "expresso" in french but it still pronounced espresso.

It is just possible some of us treat our coffee a little TO seriously btw. 3grp commercial Manual Lever machine, Commercial grinder followed by the mess that is currently my workbench and at the other end a 1kg Coffee Roaster. Not shown is 600kg of Green Coffee beans in the shack.

You are a master, nice setup!

[beanflying]

You are a master, nice setup!

No I just have a problem

Nothing EXpressly wrong with the spelling but it was a bit of 'fun' a week or so back https://www.eevblog.com/forum/chat/offtop))-do-engineers-drink-coffee-in-your-country/msg2001140/#msg2001140

[NivagSwerdna]

18F4620 what's not to like.  Nice board layout with loads of effort on the silkscreen.

I think those Trannies are actually Triacs (T830-800W?).

[amyk]

I initially misparsed the title and wondered what an "automated coffee machine dumpster" was...

[Grapsus]

Here is a very quick and very drity block diagram of the machine in the video.

Notice how the water goes through the first boiler and immediately out to the brew unit when the steam solenoid is closed.
But when the steam solenoid valve is open, there is less resistance for the water to go into the second boiler and evaporate rather than going through the coffee in the brew unit.

[Wan Huang Luo]

Going back to Dave's video;

I was kind of disheartened that Dave didn't at least turn it on or fiddle with any menus. Its clear that he hates coffee.
While the 'Chineseum' alloy     plastic case did let the rest of the machine down, it was clear that this machine was made with a lot of regard for safety. Quite the opposite of the current Hung Lo philosophy too. Hung Lo stuff looks good outside, stainless steel outer panels, you name it. Then you crack it open when it fails (quickly) and typically inside it looks like a dog's dinner.
So I'd say they had to build this to a price point but chose to compromise on the case material instead of internal construction.

Disclaimer: I am not a caffeine engineer (barista)

[thm_w]

I don't drink coffee either, and its hilarious how little Dave knew about the machine. I guess mrs eevblog does not own or want one of these.

Cold water and whole beans go in -> beans are ground to a relatively course powder -> powder is dumped into a ~3cm x 1cm disk -> water is heated -> hot water passes through the disk and flows out into your coffee cup -> used coffee grounds are compressed and dumped into a storage bin.

A cup uses about 10g of coffee (75 beans). So a typical 450g bag would last a month or two for one person.
The beans would never sit in the machine for a year, unless you are single and rarely drink coffee. At work the machine probably gets refilled every week with a fresh bag.