Decent Espresso Machines (DE1) - Any thoughts?

[>decentespresso]

My only concern here is an inadvertent inception of a channel due to a sudden drop in pressure. The flow is likely to rise at 6ml/s for approx. 3 to 4sec and then drop to 33% of 6ml/s.
Is 6ml/s the max threshold for it to achieve the desired pressure or could it be higher?

6mL/s is the current maximum flow rate the DE1+ can achieve. When we require 220V (as on the DE1CAFE) and put even larger heaters (and heat dissipation) in we'll be able to go to higher flow rates.

For comparison, my GS/3, full throttle, pumps out 8 mL/s, but that's a punishing flow rate for a barista to use, as it demands very good puck preparation or you get terrible channeling.

Generally, if you skip preinfusion and go straight to 6 mL/s, unless your puck is really well prepared, you'll have some channeling. Preinfusion around 4 mL/s really is a good thing, even if it's just for 4s.

Otherwise I think it's an excellent option to have. I can only imagine how much fun it would be writing a manual for DE1's operation
You should probably include the manual on the tablet and update with every firmware update.

My plan is to focus on videos, a few minutes long, to explain these things. I can do a much better job of explaining things that way, but also people can ask questions in the youtube comments, which then become part of the permanent record.

[>decentespresso]

Release Candidate 3 looks amazing. What can you tell us about the metallurgy of the brass in contact with the brew water in the brew head and brew water dispersion plate?

Attached are the lab test results for the brass pieces, all of which are in contact with water. I've also included a drawing of one of the pieces, so we're all on the same page as to what we're talking about.

Note the "Pb < 0.0005" number, which is the crucial one for Germany and Japan, as they are very tough on lead content.

FYI, here is a complete list of the materials that come into contact with the water, in "flow order"
- ceramic water tank
- stainless steel uptake tube
- medical grade silicone rubber tubing (to bring water to the pumps)
- (I believe) ABS plastic is what the ODE pumps use. Need to look this up, but these come from an Italian espresso machine parts company and have certifications.
- PTFE (solid teflon) tubing
- stainless steel ferrules inside the PTFE tubing
- stainless steel tubing (inside the water heaters).
- ULTEM resin (from Switzerland) for the mixing chambers and sensor mounts.
- brass (group head)
- stainless steel portafilter basket (I can supply testing certificate, if you're curious).
- aluminum drip tray cover
- ceramic drip tray

We currently (or will) have certification at each step, from the manufacturer, except for the ceramic, which we are sending to a lab ourselves for testing (though the company we're using for the ceramics is exclusively in the cookware business, and sells their products in the USA, so we are not especially worried)

[>decentespresso]

Makes sense to me, the only thing you could do to make it clear would be to add an "OR" somewhere to show it stops when either 4 bar or 10s is reached. Also I find it a little confusing that without the guarantee ticked you show a <10s and >4bar, when it might not reach 4bar. Can I suggest some sort of symbol denoting what will happen, like <10s and ➚4bar (an arrow pointing up right to symbolise towards 4bar)? And maybe a different symbol when the guarantee is checked to indicate a definite 4bar, like ✓4bar or =4bar? Just to give an extra reminder of the expected function.

In discussions on other fora, I've agreed to these suggestions from others:
- both symbols should actually be <
- that the "guarantee" word should be changed to "force"
- that the "rise to 6 mL/s" in the chart should always be displayed so as to avoid confusion ("why is it disappearing??!?!?")

and I hope that will address your concerns too.

[>decentespresso]

As soon as you introduce the pressure specification, it's not really flow control any more (looks something like cascade control).

True: my goal is less to be "pure" about flow vs pressure profiling, and instead to make good coffee. If pressure is a useful concept, I'm ok to using it, even in the beginning of what I call a "flow profile"

I haven't mentioned this before, but instead of "exit preinfusion when X bar is reached" we could instead "exit preinfusion when flow slows to under Y mL/s".

This produces identical results, but in my presenting these concepts to people, this alternative approach was even more confusing to people, so I've avoided promoting it (though this capability is available in the ADVANCED shot editor).

And just to be clear, the way this other approach works is that
- initially the puck can absorb water at a fast rate
- as the puck saturates it resists accepting water, water builds up and fills the group and then the espresso machine notices (charts) the increased pressure, and actual flow rate decreases below some set threshold.
- at that point, the pack can be considered "compressed".

If the grind is too coarse to reach the target backpressure at the specified flowrate, will a temporary deviation from the spec give you the same result as just tightening up the grind and trying again? I'll go out on a limb and say probably not. That's not to say that it won't produce a nice shot, but it might be hard to reproduce. Guess it depends on what you are trying to achieve really.

Agreed.

If your target is reproducible shots, implementing a preinfusion volume specification might be better than a time specification.

That's a really interesting suggestion, and that is explicitly possible in the ADVANCED editor, viz the arrow in the screen shot:



A major challenge I have, as the GUI designer for this machine, is that so much of what the DE1+ presents is new to people, that I have to pick between "what people will easily understand, because it's similar to what they already know" vs "what makes the most sense objectively".

I absolutely agree with you that "volume" makes more sense than "time" during preinfusion. But people have always thought of preinfusion in terms of time. Can they cope with the change?

So yeah, I could absolutely change preinfusion to have these sliders:
- Water volume: 36 ml
- Flow rate mL/s: 4.0
- (calculated for you) Estimated preinfusion time: 9 seconds

Super interesting suggestion, thank you.

It is interesting that you typically pre-infuse at a greater flowrate than your peak extraction flowrate (I do the opposite)

I think you and I are talking about different numbers.

Are you measuring actual flow rate through the puck when you write that?

I agree, that with existing espresso machines, people generally do something like this:
- preinfuse at 4 mL/s
- infusion at 6 mL/s to 8 mL/s

Or, with a paddle, they open it up a bit until there are some drops, and open the paddle up all the way.

However, if you were to measure actual water flow rate into the puck, they'd find that during infusion, flow is actually in the 2 mL/s to 3 mL/s range.

The proof of this, is that if you really were getting 6 mL/s through your puck during infusion, that you'd complete your 36g espresso shot in 6 seconds.

Do you agree?

I'm not sure that exceeding a minimum backpressure is required for puck compression - I've not seen any evidence of a threshold in the data

Perhaps we are disagreeing because of our use of different words. Instead of "minimum backpressure" what if we say "pressure measured inside the group", do you then agree?

For me, the very definition of a compressed puck is that it is creating pressure inside the group. If the pressure in the group is at 4 bar, the puck must be compressed for this to occur. If the pressure in the group is 1 bar, the puck might or might not be compressed, it's hard to tell.

In my experience, a puck is fully compressed around 3 to 4 bar.

By "a fully compressed puck" I might suggest this test:
- if you slow the flow rate down to 1 mL/s for 20s, does pressure in the group increase or not?

If not, then I would say the puck was not compressed (water is dripping through the puck).

If pressure does increase, for me the puck was compressed (water is building up behind the puck, increasing pressure).

Interesting conversation, thanks.

[HBDecentRefugee]

That, to me, is an exceptionally "clean" water pathway. The Pb levels of the tested piece, presumably the group head, is exceptionally low at less than 1/50th of what California considers lead free. The C23000 designation on the shop drawing for the distribution plate or shower holder appears to be inconsistent in that C23000 is a roughly 85-15 cu-zn ratio. Perhaps it is a different material from the group head.

[>decentespresso]

That, to me, is an exceptionally "clean" water pathway.

Three years ago, when I started down this journey, I first began by reading Amazon.com reviews of existing machines. Over and over, people focussed on the water path, with particular panic associated with aluminum and BPA plastics. I saw that this was such a big deal to people that having any worries in the water path of a machine basically nuked your ratings on amazon and you lost all community support in your product. That's a good lesson to learn.

It doesn't sound like you need convincing, but I've had two people with science backgrounds, but who were very worried about water contamination as they considered purchasing a DE1, dive deep into PTFE/teflon and Ultem (the resin we use for the mixing chamber) and report back to me that they were pleasantly reassured by what they found.

Note that nothing in our water path is "coated", as my assumption is that coatings will eventually wear or flake off and the protection they provided will be voided.

The Pb levels of the tested piece, presumably the group head, is exceptionally low at less than 1/50th of what California considers lead free. The C23000 designation on the shop drawing for the distribution plate or shower holder appears to be inconsistent in that C23000 is a roughly 85-15 cu-zn ratio. Perhaps it is a different material from the group head.

The C23000 on our drawing was put there by our engineer, but when we talk to manufacturers to make this piece, they tell us what they recommend using, which I feel is how it should be (they're the experts). We ask for a testing report, like the one I posted, and compliance proof with the German low-lead standard.

The Chinese manufacturer we're using for these brass parts is exclusively in the espresso machine parts business, mostly working with Italian (high end, commercial) and German (low end, home) manufacturers. I have a pretty high level of confidence in their work.

All 3 pieces in the group head (top, middle, bottom) are made of the same material.

[mentasm]

Ever considered a Basic mode and an Advanced mode for the GUI? Keep thinngs real simple with only a few options to play with and in Advanced open up much more of the configuration that you are discussing here.

[>decentespresso]

Ever considered a Basic mode and an Advanced mode for the GUI? Keep thinngs real simple with only a few options to play with and in Advanced open up much more of the configuration that you are discussing here.

Yes. It's not clear in this discussion, but there's a "ramp" already in the GUI design.

My intention is for "basic" mode to be "choose a preset". The "presets" tab is the first tab you see when tap "settings".

Next level of difficulty is to edit a preset. Generally, people will only change existing ones a little bit.

Next level of difficulty is to change a preset a LOT, maybe making your own.

And final level of difficulty is for someone to edit (or create) an advanced shot.

Because there are advanced users on this forum, that's why I've engaged in this conversation of fairly advanced coffee topics.

[>decentespresso]

Second attempt: preinfusion and flow profiling

Here is a new draft of the user interface for configuring pre-infusion, when making a flow controlled espresso on the DE1+. Thanks for all the feedback, it really helped.

What's changed:
- The flow bar was moved from horizontal to vertical, so it's like the other flow-bars on the page.
- Both seconds and max pressure are now labelled with a < and they're stacked on top of each other, to make it clear that they both apply.
- The "guarantee" concept has turned into a "rise" checkbox which simply means the DE1+ should try to "rise" the espresso to this pressure (at the end of preinfusion)

I've made a small animation showing how the chart changes as you turn this "rise" feature on and off.

What do you think?

[>decentespresso]

Color coding an espresso profile

A few days ago Michael Hollesen suggested color coding the espresso sections and uploaded a photoshop mockup he made of his idea.

I liked where he was going with it, and today tried to implement something similar.

Let me know what you think of this direction.

[level3ninja]

The colours are a great idea to make the interface more intuitive. I think it would be nicer to have the same weight line as the blue but make it coloured instead of the cloud around the line. I think red for preinfusion, green for hold, blue for decline. You could even have the rise function a different shade of red with that section of the line matching if enabled.

[>decentespresso]

The colours are a great idea to make the interface more intuitive. I think it would be nicer to have the same weight line as the blue but make it coloured instead of the cloud around the line. I think red for preinfusion, green for hold, blue for decline. You could even have the rise function a different shade of red with that section of the line matching if enabled.

I tried that, but because the same color is used on the thin line as on the big square buttons, if I use a color vivid enough to be seen on a thin line, it is LOUD and a bit vulgar, when the same color is placed on a larger area.

[>decentespresso]

Tracking flow rate into the cup

This video demonstrates our ability to integrate with a Bluetooth scale, and thereby chart the real-time flow rate of an espresso into the cup itself. The scale weight is automatically tared when the shot starts, and you can see the drops start around 8 seconds of preinfusion and speed up to approach the water flow rate as measured going into the puck from the machine.

Note that the blue flow rate line is calculated on this machine (not using a hardware flow meter) as we are trying to create an accurate physics model to determine flow rate by counting water pump strokes. We wrote this "gravimetric flow meter" in order to test and improve our physics model.

We are working on making our own Bluetooth scale, as well as an integrated scale in the drip tray of our upcoming DE1CAFE model.

Naturally, in the future, the espresso machine can stop making coffee when the desired in-cup rate is reached.

[>decentespresso]

Insights from tracking weight into the cup

It's really interesting to be able to see the rate at which espresso pours into the cup. I think it's going to lead to some insight.

In the espresso below, I am using a somewhat fine grind, 18g dose, the coffee is fairly old (4 months) and medium-dark roasted (not so yummy). The two graphics are the same espresso: one is a "zoom" of the other.



What's interesting about this shot is:
- even though preinfusion has definitely finished (pressure is high)
- the puck continues to absorb water
- which you can see because the water out of the puck (brown line) is half the speed of the water into the puck (blue line)
- and as the puck becomes fully saturated (toward the end of the shot), the flow rate in finally equals the flow rate out

I think that a slower, longer preinfusion would fix this, as would a coarser grind (the beans would have less water holding capability).

That would change the flavor, and it'll be interesting, with this new data, to see if it's possible to "make the chart look good" equal "espresso tastes good"

[MrJack]

It's really interesting to be able to see the rate at which espresso pours into the cup. I think it's going to lead to some insight.

In the espresso below, I am using a somewhat fine grind, 18g dose, the coffee is fairly old (4 months) and medium-dark roasted (not so yummy). The two graphics are the same espresso: one is a "zoom" of the other.

[ATTACH=CONFIG]17126[/ATTACH]

What's interesting about this shot is:
- even though preinfusion has definitely finished (pressure is high)
- the puck continues to absorb water
- which you can see because the water out of the puck (brown line) is half the speed of the water into the puck (blue line)
- and as the puck becomes fully saturated (toward the end of the shot), the flow rate in finally equals the flow rate out

I think that a slower, longer preinfusion would fix this, as would a coarser grind (the beans would have less water holding capability).

That would change the flavor, and it'll be interesting, with this new data, to see if it's possible to "make the chart look good" equal "espresso tastes good"

[ATTACH=CONFIG]17125[/ATTACH]

That is truly fascinating.

The time that mass in the cup is first recorded really surprised me; slightly earlier than I would have expected looking at the other data.

Is the flowrate measurement (blue line) in that shot from a physical or "virtual" meter?