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#21: Post by decent_espresso »


Back in Hong Kong

Back in June 2019, Bugs and I left Hong Kong for what was supposed to be 9 months of intense outreach (many, many cafe demos on road trips), and several big trade shows. We managed to be at World of Coffee in Berlin, and CoffeeFest New York, and then covid happened. Trade shows we had booked in Brooklyn and Portland were cancelled.

To compensate for the closures, I've been doing regular Zoom calls which anyone can join, and they feel like they're actually much more impactful than trade shows.

We've been living in California since February, waiting for "covid to blow over". That didn't happen. I applied to be a HK Resident, so that Bugs and I could get back there, and be back among all the staff we left to run the show while we were gone. That paperwork was approved 10 days ago. HK is only letting residents in, to try to control covid.

The flight from California to HK was 13 hours long, plus two hours of immigration, and multiple checks. Mandatory (but free) covid tests. 10 hours waiting in a big converted trade show hall in HK. After landing at 5:10am, at 7pm we were allowed to go to our rented apartment when we got stamped proof of covid-freeness.

We now have a "StayHomeSafe" HK government app running on Bugs' iPhone, tracking us via bluetooth enabled wristbands. We're in a strict quarantine for two weeks, in a very pleasant place called "Happy Valley". Waiting now for our first coffee in days to be delivered, from the earliest delivery that would come (9:30am sigh) but a very nice pastry . It'll just be Illy beans, but I'm ok with compromising at this point.

We ran out of coffee beans 2 days before leaving California. Both bugs and I immediately got day-long headaches, from caffeine withdrawal. We're now fully detoxed, and ready to up our caffeine levels again!

At 11:30am, Coffee Academics opens up, and they deliver. They're on some of the "top 10 worldwide best cafes" lists, so we're not at all unhappy with that choice. Plus, 5 years ago when we started Decent Espresso here in HK, Coffee Academics was our local, at the hotel where all of us were living, so it's great to come full circle, to an old friend


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#22: Post by decent_espresso »

K-Affe wrote:Not understanding what "Turing complete" really means
With computers we call something "Turing complete" if it can run any program that any computer could run. Modern computers are all Turing complete. Yes, this is a simplification: read the wikipedia page for a more rigorous definition.

Espresso machines are very much not Turing complete: they generally only run one program, though you can modify that program a bit (runtime of an espresso, for instance).

Espresso machines very much encode their program, in the hardware. Ie, the plumbing decides how the coffee is run. It is not changed, generally, without changing the plumbing.

Not knowing "what way of making espresso is best" we set out to make a coffee machine that could run any espresso making program.

There are only a few parameters, after all. The big ones are temperature, flow, pressure. Secondary ones like water distribution, basket size (height, width, holes...), head space above the puck are also important.

So... when I say "a Turing complete espresso machine" I mean "an espresso machine that can emulate all espresso machines before it, and all theoretically possible espresso machines you could conceive of". Naturally, that's not entirely true, as there are limits. We can't boil water at 120º, or use alcohol instead of water as a solvent. We can't jump water temperatures around 20º in under a second. But generally speaking, we've come close to making a Turing Complete espresso machine.

The only main thing we can't do is VERY fast preinfusion. Some machines have a "water hammer" approach, and that's cool: it gives a different style of drink. But that's the main limitation I can think of with the current Decent hardware.

Which is why most of the progress in the past few years, in terms off coffee drink quality on Decent Machines, has been due to software improvements.


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#23: Post by false1001 »

Hey John,

Would you ever consider making 5 or 10lb springs for the v3 tamper?

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#24: Post by decent_espresso » replying to false1001 »

Maybe we'll end up there, but at the moment we need springs that are a bit stronger than that in order to smoothly retract the tamping base back to its starting position. Our tamping base is still stainless steel, and a bit meaty, for a more traditional feeling tamper.

For a really light feeling tamp, nothing can beat the Force Tamper, as it's super thin. There are tradeoffs, naturally, with each approach.


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#25: Post by decent_espresso »

Future drip tray design

Ben has been working on a new drip tray design, to enable easier integration of a scale placed underneath, out of the way.

Besides being a little bit shorter, there is a cutout space for the drip tray cover to come up and around.


Like so:


We'd like to make this part using a new process for us: ceramic coated aluminum. This is the same stuff you might have seen in camping gear stores.

It's still ceramic, so it has the same food safety and longevity as our current drip trays.

However, the shape and strength is defined by a cast aluminium inner. This makes it much more resistant to breakage, thinner, and lighter.

This'll mean :
  • more accurate weighing of your espresso,
  • less worry about breakage,
  • better fit on the DE1 (due to tighter tolerances)
  • about 1kg (2.2lbs) lower weight, for easier transportation of your DE1
  • and better fit with the current stainless-steel drip tray cover design (less wiggle) due to better tolerances.
  • a plumbable version will have a hole on the far side (not the center) so that an under-tray drip pan can be used which doesn't get in the way of the scale. This will allow a scale to be used even in plumbed-in situations.
Here a sample of what this kind of ceramic-on-aluminum process creates. You can see that this photo is pretty similar to what we have today. And it looks pretty nice.


We're having a difficult time finding an affordable supplier. Manufacturers are very nervous about taking on new clients at the moment, due to all around global uncertainty. I think we'll eventually get there, but it's going to take some time.

The hope is to have this for early 2021. It will (of course) work on all DE1 historical models and be available at a reasonable price, on our web site.

Hopefully some of the people who make existing Scale adaptors, will come out with versions that work with this new drip tray model. I'll be sending free samples of this new part, to those who have design drip tray adaptors, to encourage this.

Note that we're planning on making the water tank out of this process as well. That's how we get 1kg (2.2lbs) of weight reduction, as our 2 liter-capable water tank, being made of porcelain, is fairly heavy.


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#26: Post by decent_espresso »

An Insight about different espresso recipes
by charting the first derivative of the puck resistance

"Puck resistance" is a concept I added to the DE1 a few months ago, but we've been struggling a bit to understand what to do with the information.

for those that like mathematics, it is FYI calculated as:
pressure / (flow ^ 2)
Collin Arneson yesterday posted an interesting writeup arguing for the 1st derivative of the puck resistance number. This is a chart of the change in puck resistance.

This number shows us when puck integrity falls apart, regardless of flow rate or pressure changes that might obscure that trend.

What I found interesting was that it's also a way to compare espressos recipes.


Those recipes that result in linear puck degradation should make better tasting.

The author's tests with Rao's Blooming seems to confirm this. Pucks hold up better after a 30 seconds bloom, and degrade in a cleaner fashion.



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#27: Post by decent_espresso »


Zoom call: all about the Decent Tablet app

Bugs and I are in quarantine in Hong Kong for another 10 days, and I'm without a DE1. While I'm happy to host a Zoom call, I can't make any coffee.

However, I do have access to the Decent app on my Mac and can "share screen" so I can do a "focus on the Decent App" zoom call topic.

My thinking is that I'd
- walk through every screen of the Insight Skin
- and all the Settings pages pages
- the "heart" section,
- God shots,
- Your Setup,
- exporting CSV to Excel,
- and whatever questions people have about the app.

If Damian is available, he will do a complete walk through all the DSX skin features. - Meeting ID: 841 8733 8701
- August 1 - Saturday 6pm (pacific USA time)
- August 1 - Saturday 9pm (east coast USA time)
- August 2 - Sunday 9am (Hong Kong time)
- August 2 - Sunday 11am (Melbourne time)

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#28: Post by decent_espresso »

Here's a Youtube video capture of the zoom call from today, covering the decent tablet app.
FYI you can download the app for free, and run it on Windows/Mac/Linux