Getting a perfect distribution of grounds to make an espresso is really difficult. Your grinder and your "grooming technique" are key, and they have a huge impact on the quality of your espresso drink. This is one of the hardest things to learn, and even the top baristas struggle with this problem.
A major issue is that you literally do not know what's going on inside your puck.
A tool like the OCD appears to give you uniform density, but research from Socratic Coffee has shown this be illusionary. The OCD makes your espresso quality more variable, despite appearances.
After you tamp, you likely still have areas of different coffee ground density. If you use a bottomless portafilter, you can see the nefarious effect of this when you pull your shot.
We've designed a tool, integrated into our calibrated tamper, which (if it works) will show you what's going on inside your puck after you've tamped.
Attached are some photos of the design we have in mind, of a tamper integrated into a pressure sensor. A preliminary test with a tamper on a rectangular sensor at about 50lbs of force, showed that this could work.
We've discussed this with @sensitronics and are awaiting a proposal from them to build such a thing. Initially, we would make prototypes, for use in understanding grinding and grounds distribution better. If it's economically feasible, this could become a product.
Last edited by decentespresso; 9th December 2017 at 03:12 PM.
I was once married to a soils engineer in a university where I vicariously learned stuff about particle behaviours in soils that can be generalised to granulated products like coffee. Since you mentioned that your coffee 'guru' only taps the portafilter before pouring a shot I have been experimenting with not tamping and doing just that - with surprisingly consistent results. So it got me thinking why this could be so, and recalling that prior knowledge of soil and gravel behaviour under various conditions. The TLDR version of that may just be that a high frequency vibration would be a better way to achieve uniform compaction of different sized and unevenly shaped particles, rather than steady tamper compression. Certainly makes sense of why just tapping the portafilter a few times can give me better results without as much channeling. Would be interesting to try it with a vibrating pad
At any rate, your theory about not tamping is plausible to me. I've done some tests with extremely light tamping and found it to work just fine as well as heavy tamping.
But for me the basic idea is "what you can't measure, you can't improve" and thus before we play with improving grinds density, we first need to be able to measure it, and see if what we're doing improves things. Socratic's TDS measurements are the current best-available-method, but more indirect than I'd like.
Instead of measuring TDS, what we do at Decent is make a constant-flow (2ml/s) espresso and look at both the peak pressure achieved, and how long the pressure takes to decay. The higher the pressure, and the longer the decay period, the more uniform the grinds distribution was. Note that we hold beans, grind and dose weight constant.
I use a double spout all the time for my afternoon espresso shared with my girlfriend, though yes it does break the crema up. However, since most people add milk or water to their espresso, they're breaking the crema up too.
To add a bit of information: our group head portafilter-fit is La Marzocco standard, and so any portafilter that fits LM machines will fit ours as well. If you don't like what we offer, you can go 3rd party.
Going on a tangent....I'm not very happy with any double-spouted portafilter on the marketplace, including ours. All of them seem to have a surface tension problem where the shot, when starting off for the first few seconds, doesn't spill evenly into both cups. One side gets more of the first few seconds, and so it tastes different. The 32g espresso I just made was split and was 4g lighter in one cup than the other. Yes, I actually weighed them, as this problem is bugging me and I'm collecting data. Girlfriend preferred my drink to hers, so the taste difference is noticeable.
We've done some preliminary work on solving this problem, and have some ideas for a new double spout, perhaps for next year.
I thought uneven spout pours were due to unlevel benches out uneven distribution leading to uneven flow?
However, what we observe is that surface tension causes one side to be chosen and for the espresso to not flow out at all from the other side for a few seconds. Very fast espressos don't show this. "Slow developing" espressos are particularly affected by this problem.
To "remediate" this major problem in my life....
When I pull split shots, I have a thermometer probe handy when the shot starts. When one side is chosen by the liquid, I quickly insert the probe into the double spout, and defeat the surface tension preference to get the shot pouring down both sides.
If you can't measure it, you can't improve it. - Peter Drucker
Link: If You Can
My general feeling is that you're changing something to improvement something else, but you can't measure what you're trying to improve, then what you're doing isn't science, it's a hunch.
If you can't "measure" what you are trying to change, then how can you know whether you are changing it? Much of human progress has been enabled not by hypotheses (i.e. hunches), but by advancement in the measurement technologies required to investigate them.
This feels to be somewhat off topic. To remain off topic...
Any science experiment starts with a hypothesis, is which is then proved or disproved by some sort of measurement...
Some kind of nozzle that will allow the coffee to pool on the base of the portafilter before flowing down through the spout will most likely split the flow more evenly.
Did you check that the machine was 'leveled' during this test?
Was the spout 'square' to the face of the machine?
What was the flow rate ? I.E. combined "yield / total time of pour" ( divided by)
If you do further checks with a naked handle & mirror ...with say, for example,
a 17g plus dose, say around a 40ml pour in 35sec,
which is a tight slow pour.... the first few grams of liquor will generally drop from the basket as a
few droplets and more often than not from a particular segment or sector of the basket open area.
Before opening up into a combined circular even flow around the basket.
This could be said to be the natural order of the flow finding its way thru the puck.
Or saying it in another way the liquor may not always just hit with a controlled flow forming a whirlpool spout
which is falling evenly from the centre of the open area of the basket.
A by product or behaviour of the bean grind dose tamp set up of the puck in the basket.
Until proven / shown otherwise!
The first response would be to be develop an easy quick adjust leg / height adjustment.
This does appear to work to evenly distribute the liquid.
However, crema gets jammed up in all these small calibrated holes.
So, I'm not currently happy with this approach.
Very thin, laser etched "guide lines" might be a better way to break the surface tension.
Alternatively, a hydrophobic coating in the split might do the job, in a way that has fewer downsides.
Personally I find the transparency and the shape to be OMFG gorgeous.
We use the standard IEC cable to plug our espresso machines into the wall. These are the same cables you find on computers. Two years ago, I noticed that the cable was often warm, and while back in the US, I bought a thicker cable (for $29 https://www.amazon.com/6ft-Nema-5-15...dp/B00S5K9G52/ ) and found that the cable was now no longer warm.
We've just received 1000 power cables for the US, UK and EU standards. For the EU, we're using the hybrid Germany/France standard, which can ground either top/bottom or with a dedicated pin.
We bought the thickest, most heavy duty cables we could readily find. In the bottom photo, you can see the difference between ours (left) and the common PC cable (right), which is what we've always used.
For the techies out there, our US cables are 14AWG, while our EU/UK cables are 16AWG (1.5mm˛).
Especially in the US, where 110V is not-that-much-power, we're happy to enjoy the extra juice that a good cable provides. And that's not even mentioning the ecological issue of not wasting electricity because of the cable warming.
And for us Aussie customers what connecter?
Been sitting on the sideline watching this thread with interest over the past 12 months.
The last couple of posts concern me, there is more to Australian compliance than simply hanging the appropriate 3 pin plug on the end of a cord.
I've seen little addressing the issue in this thread, the Australian govt takes electrical compliance issues seriously and polices the matter quite zealously, as it should, consumer safety is involved.
SAA Approval Process Australia | SAA Approvals
I was told by Intertek (our safety testing service) that Australia's compliance requirements largely follow the EU guidelines, and that Intertek will be able to confirm that we are in compliance (or not). Our initial path for safety certification is first UL, then CE, then applying for the rest of the world: Australian, Singapore, Taiwain, Thailand all have their own certifications (and others besides). However, Intertek has told me that this is largely paperwork. For a new product, and a company of our size, it's not possible to get certification in every locale, at launch.
However, I don't see any major issue with a customer importing a EU/CE certified espresso machine into Australia.
I think it is fair to say most buying a machine from your initial batch are aware they are lucky to be in on the ground floor of something new and potentially wondrous. After all the factual comments in your very informative and exhaustive thread some may be tempted to take your comment as fact. At the very least for a domestic user they would find no household insurance, for a business user, even just a two person office, they would find no workers compensation insurance is applicable and in a work environment where electrical items need to be tagged this isn't likely to pass. These are just the tip of the iceberg. I doubt they will have much legal comeback on a company domiciled outside of Australia (your website suggests either HK or USA) without prohibitive expense.
I am not saying don't import your product but have your eyes open when you do and control your risk, it isn't really no major issue.. It is a device which really has no equivalent and so some risk must be taken if you want one, which I think all who have ordered are aware.
" I don't see any major issue with a customer importing a EU/CE certified espresso machine into Australia."
I think you interpreted differently than I meant it. I meant it "from an engineering and safety perspective", as Intertek has told me that AU does not materially differ from EU safety standards.
I really can't speak to Australian rules about workers compensation, your household insurance, etc, it depends on your country, and it's beyond our ability to dive deep into every single country's circumstances. Maybe your home insurance covers you for EU-certified appliances, maybe it doesn't.
For now, if Australians want to buy our machines, they'll be getting a UL/CE certified machine. I wouldn't think we are the only product that people are buying abroad and importing themselves into Australia.
If you'd rather not have any worries about your Decent machine under Australian rules, then by all means, wait a few more months until Intertek has done the necessary to certify us as compliant for your country.
It's our intention that by summer 2018, we'll have local certification for every major country we sell to, and that includes Australia.
It won't be long before you'll need an ABRA sticker on...
Approved By The Republic of Australia
ERAC - News - https://www.acma.gov.au/Industry/Sup...duct-labelling
I am sure all early adopters are aware and happy with what they are getting in to. I just think it isn't fair to try and pretend it doesn't really matter, it's just paperwork. The reason companies (including all the other espresso machine importers on this forum) spend thousands on their RCM is so the clients wont have to if there is a problem. That is the reason you are getting US and Europe approval, too big a market to ignore and too expensive to be sued if you didn't. I have already detailed on this forum the problem a friend had with a $25k claim when an unapproved dishwasher flooded. I am sure a device which has water and electricity flowing through it and controlled by a tablet shouldn't give any trouble at all, but if it did would give pause for thought with no cover for repair or serious injury. That said all of that is a non issue with your second approved batch.
PS I still really like the concept of your machine and cant wait to read the first reviews
Last edited by 338; 13th December 2017 at 10:54 PM. Reason: spellcheck!
Today, testing samples of 21 different designs for steam wand tips arrived.
Our DE1/DE1+ machines come with a steam wand tip that has one hole. This makes microfoam quite easy to create, with the medium-power steam those espresso machines provide.
With the DE1PRO+ and DE1CAFE, we'll have a higher powered steam heater available, and thus the option to direct steam into your milk jug in various ways.
Decent engineer Ben Champion has been studying the various theories behind steam wand designs, as well as putting forward his own ideas, and those of our advisors. He created these 21 designs so we could test them.
At the moment, we have 3 samples of each design, CNCed out of stainless steel. Once we pare down the list of feasible tip designs, we'll want to work with our customers to beta test them, and to see which they like, as well as what interesting designs we might have missed.
I've used the Sproline Foam Knife Sproline Foam Knife steam tip | Talk Coffee on our two-group E61 machine, and found that to be much easier to control than the 3 hole tip that came with the machine.
It's my hunch that different tips will be useful in different situations. Very high powered steam will likely need a larger aperture, such as a "blade" shape.
300 mixing chambers arrived at our factory today. These are made of a medical-grade resin called "Ultem", and they have 3 valves attached.
This part is where water comes, its temperature and pressure is read, and then the valves decide if the water should go to espresso, steam, hot water (tea) or be recirculated because it's not yet at the right temperature.
These were made for us by our Italian valve manufacturer ODE because they're the first production use of a custom-made (small format) valve and they were concerned about leakage.
It turns out that they were right to be worried. 3 managers came over yesterday to tell us that they experienced a 60% failure rate. If one of those 3 valves leaked at 19 bar of pressure, the entire thing has to be discarded.
They kind of lost their shirt making these for us, because Ultem is a very expensive material. For the next run, they've asked us to make some small design modifications that they think should greatly reduce the defect rate.
As you can see in the photo, this is a high precision, low-tolerance part. It's also expensive, at $88 each, our cost, at quantity. Figuring out how to make this part less expensively, and more reliably, will be something we focus on over the next 6 months.
Just had to add my second crack to this.....
John, had been very clear as to the specifications and the levels of compliance the first 300 units will adopt and we were all constructively well informed before we signed up for a unit, ......the trade-off for being an early adopter, but one I am very happy to live with.
Australian regulations and bureaucracy don't necessarily add any material levels of safety .... I recall in the 70's when Mercedes Benz airbags needed to be disabled as airbags were not then in ADR's .... .go figure !
Very much looking forward to a Decent Espresso from my EU/CE certified device.
PS You may have misinterpreted my comments, I don't think there is anything not safe, especially with CE approval. My thoughts were the product is 97% there with CE approval, it is only 3% more effort to give Aus purchasers the same protections USA and EU purchasers get.
I have Mercs. The first air bags here were the '89 126 then the '92 124 and 201. As an early bird I'm really looking forward to getting the DE1. What I can't understand is why the Decent discussion on Kehn's HB has been terminated. The DE1 is the most significant new espresso machine in decades so fortunately the pommy forum and Snobs are more mature in their approach to allowing an evolving robust discussion about the DE.
Here's a photo of some of our espresso machine parts that have arrived in 300-machine production quantities.
I thought you might be interested in some comments about some of them.
1: these are how water arrives onto the coffee puck, and these parts exist in the "group head".
1a: is shaped like an apple because our fluid dynamic simulations found this was most effective in breaking the momentum of the water as it arrived in there. Small calibrated grooves evenly spread the water out 12 holes (in 6 sections).
1b: is where the water goes next, and these are concentric "Step ladders" of holes, calibrated so that at 1ml/second, 2ml/second and 3ml/second, each next concentric circle is used. This is so that if you use a slow preinfusion to make your coffee, water will be evenly distributed around the puck. Before these grooves, slow preinfusion caused a random section of the puck to get all the water (somewhat arbitrarily depending on surface tension and microparticles on the plate)
2: is a 3D printed "strain relief" kind of "girdle" that holds this tube in place, so that it does not exert twisting pressure at the joint, which could lead to a leak in a year or two. The page on the left shows how the 3 mixing chambers come together.
3: this metal box slows down the high-pressure water when your espresso finishes, so that you don't get splashed when it arrives in your drip tray.
4: these two "mini mixing chambers" (one is before the heater, one is after heater) mix water and also hold temperature sensors, and are made of Ultem.
5: the custom-stamped rubber sheets, with self-adhesive backs, are to prevent vibration from propagating out of the water tubes into the chassis, which could cause rattling noises.
6: we're color coding our water tubes with shrink tubing, to make it easier for us to assemble the machines, and to make it easier for repairmen and others to understand how the machine fits together. Originally, we found 6 colors, but two weeks ago found a source for 11 colors, which allows us to avoid having to use two colors to label a single tube.
Do you have any questions about anything else you see in this photo?
Surprisingly,[for me anyway] having watched and learned through postings over time, pretty much all the components in the photograph are recognisable! Good to see what's going into it from one stage of development to the next, and now nearly finished.
There's a bigger issue, though, with how Decent and HB interact, and that's that HB's behavior rules are set up for the common situation of companies using HB to market to people. My interest is in collaboration, especially with the hardware hacker/tinkerer/obsessives side of the home coffee world, and HB's existing rules don't work well for that. Dan seems to want to make that possible, and I expect that on HB we'll see a discussion of this vendor cooperation concept, *after* Decent starts shipping.
'Tis good to see such a robust discussion.
Java "Keep it up!" phile
Toys! I must have new toys!!!
Post out of context.
Last edited by Yelta; 21st December 2017 at 10:07 PM. Reason: No longer relevant
I realise there was no malice there JMcCee, these things do tend to escalate pretty quickly.
A year ago, I researched current best practice in boxing things up for shipping. What I read promoted the concept of "crush zones" rather than "rigidity". The idea is that if an airplane baggage "thrower" drops the espresso machine onto the tarmac, that the packaging should be able to crush at the point of impact, and that the tarmac should never come into contact with the goods.
From what I've read about designing cars for crashes, this sounded very familiar. Better to have the packaging get badly crushed than the goods inside.
We've designed a box-inside-a-box, with a 5cm "crush zone". Fairly high-density foam holds the inside box in place. Those foam corners will also be the most likely to take the brunt of a package drop, so they need to be able to absorb and then gently bounce back.
We'll also be testing each espresso machine in our "shaking machine" before quality-control testing. That will simulate most of the voyage, but we also want to be able to withstand a serious package drop.
There is a custom box maker a few floors above us in our building, so we're able to buy these in small lots of 100 at a time. In the future, when I have a bit more time available, I'd like to research foam corners made out of recycled material.