Coffee - do you and how do you consume it?

[D!sco]

My Gaggia has been given what is (hopefully) it's last mod. It took a long time to ship the upgrade kit in from Hong Kong, but luckily when it arrived all I had to do was a chip swap and a screen swap. That only took an hour.(The rest of the mod had been done already with a previous generation of screen and chip.**) The extras, like hardware scales and water depth sensors were another challenge to get working correctly, but were worth it in the end. Infinite recipes and infinite shot data storage accessible over the new webUI are the primary features in the upgrade. The screen is fine, but once you access it over a tablet, it almost doesn't matter. I spent a few months chasing down longstanding issues and tuning it up, and until I have an issue again, I can't picture getting a new machine. Options like the Decent and Meticulous are inviting, but don't really offer much of an improvement for the money at the moment. I'm $1200 all in before my home roasting setup tips it to $1700. As much as these things are worth it I can't picture spending much more without needing to serve more than my home and the occasional guests who usually want tea anyways.

 

[antcollinet]

My ECM barista blew up a couple of weeks ago. Well technically it didn't blow up, but it did manage to over pressure, and eject the boiler contents quite violently via the safety valve. This means at least three "off" mechanisms have failed, so I decided to replace rather than repair.

My new machine, Rocket Espresso Appartamento TCA arrived yesterday to sighs of relief from the coffee aficionados of the house. I have to say, it looks quite pretty.

 

[delta76]

My ECM barista blew up a couple of weeks ago. Well technically it didn't blow up, but it did manage to over pressure, and eject the boiler contents quite violently via the safety valve. This means at least three "off" mechanisms have failed, so I decided to replace rather than repair.

My new machine, Rocket Espresso Appartamento TCA arrived yesterday to sighs of relief from the coffee aficionados of the house. I have to say, it looks quite pretty.

View attachment 498254

Looks pretty, I'd give you that. On other hand I am done with E61. Too much hassle with maintenance, subpar thermal stability. All that for the look, and "easy to repair"

Added a bluetooth scale to my set up (Bookoo Themis Ultra) and it is a great addition. Almost game changer. Auto tare at beginning of the shot. Auto stop at desired weight. I wish it would auto turn on as well but only Decent scales have that feature.

 

[xray]

My ECM barista blew up a couple of weeks ago. Well technically it didn't blow up, but it did manage to over pressure, and eject the boiler contents quite violently via the safety valve. This means at least three "off" mechanisms have failed, so I decided to replace rather than repair.

It was probably the Solid State Solenoid for the heating element. When that fails closed it bypasses everything. I had a hard to see line leak that shorted the activation side and basically left the heating element on even with the power switch off. For some reason the load side bypasses the power switch and went directly to mains. I replaced the SS solenoid twice before I figured out the root cause was a leak.

 

[antcollinet]

It was probably the Solid State Solenoid for the heating element. When that fails closed it bypasses everything. I had a hard to see line leak that shorted the activation side and basically left the heating element on even with the power switch off. For some reason the load side bypasses the power switch and went directly to mains. I replaced the SS solenoid twice before I figured out the root cause was a leak.

It's not solid state - it is an actual relay. I've replaced it once when the contacts burned and it wouldn't come on.

Now I know the contacts are welded closed (or the control box has failed in some other way that results in relay locked on - though I'm betting on failed relay again), since the element heats even when the water tank is removed and that shouldn't happen. I also know the feed to the element goes from the relay through two separate heat limit stats (I traced the wiring when I replaced the relay last time). So both of those have to have failed also, to allow the boiler to over pressure.

 

[xray]

It's not solid state - it is an actual relay. I've replaced it once when the contacts burned and it wouldn't come on

AFAIK most E61 machines including the ECM use a SS relay for the load side and a mechanical relay on the control side. I've also replaced the smaller mechanical relay in the controller that sends the signal to the activation side of the SS relay.

[Edit] I just had a look at your postings at coffee forums and see that indeed yours is a mechanical relay inside the controller. Mine is a SSR external to the controller which is how it got shorted by the leak.

 

[TurtlePaul]

Technically pumps or lever do not deliver pressure, they deliver flow rate. The pressure is created by the puck not he pump/lever. How much pressure do you think will be created if the puck wasn't there? Yet you always get flow rate.

The lever (or pump) is doing all of the work, so it delivers the pressure and the flow rate. The pressure on a level machine is proportional to the weight placed on the handle. The flow rate on a lever machine is proportional to how fast the lever is moving.

 

[antcollinet]

The lever (or pump) is doing all of the work, so it delivers the pressure and the flow rate. The pressure on a level machine is proportional to the weight placed on the handle. The flow rate on a lever machine is proportional to how fast the lever is moving.

While true, neither the pump, nor the lever will generate pressure if there is no resistance from the puck. Without that, you'd have to have firehose level of flow to generate 9 bar of pressure.

With a course grind, (or an uneven puck which "channels") there is less pressure, as the flow can move through the puck more easily. Essentially the art of grinding and tamping is to create sufficient resistance to flow that the pressure reaches the optimal 9 bar.

 

[RexrothPigeon]

the optimal 9 bar.

ymmv but 9 bar is far from optimal for the coffee I most enjoy

 

[delta76]

ymmv but 9 bar is far from optimal for the coffee I most enjoy

9 bar is like the "default" standard for pump-based machines. just like 58mm, it's there because of historical reasons not because it creates better espresso.
lever machines have declining pressure, and more people will prefer those level "profiles" than the pump ones

 

[xray]

What's important to the extraction process is flow rate not pressure. Pressure is just the result of flow rate through a given cross sectional area and permeability. For a given machine the cross sectional area is fixed and what you control is the grind and dosage, both of which determine the permeability. Vibrational pumps and rotary pumps both deliver a fixed flow rate. Lever pistons deliver a flow rate determined by the rate of displacement. None of them deliver pressure directly.

 

[delta76]

What's important to the extraction process is flow rate not pressure. Pressure is just the result of flow rate through a given cross sectional area and permeability. For a given machine the cross sectional area is fixed and what you control is the grind and dosage, both of which determine the permeability. Vibrational pumps and rotary pumps both deliver a fixed flow rate. Lever pistons deliver a flow rate determined by the rate of displacement. None of them deliver pressure directly.

not true, flow rate can be controlled by adjusting the current - case in point, Decent which uses Vibration pump (as they explained, beside other things, is the quickest to change the flow on the fly)

 

[Titurel]

While true, neither the pump, nor the lever will generate pressure if there is no resistance from the puck. Without that, you'd have to have firehose level of flow to generate 9 bar of pressure.

With a course grind, (or an uneven puck which "channels") there is less pressure, as the flow can move through the puck more easily. Essentially the art of grinding and tamping is to create sufficient resistance to flow that the pressure reaches the optimal 9 bar.

By George, I think you've got it. Once you start viewing the puck as "the load," the next logical step is to build an electrically equivalent model for espresso much as Thiele and Small did with loudspeaker performance.

 

[xray]

not true, flow rate can be controlled by adjusting the current - case in point, Decent which uses Vibration pump (as they explained, beside other things, is the quickest to change the flow on the fly)

That's a pedantic point. Most espresso pumps are designed for a fixed flow rate at line voltage. Of course introducing an external component like a rheostat to alter the line voltage will change the designed flow rate, that should go without saying. It would be operating outside of the designed parameters. There may be espresso pumps with rheostats built in but most do not have that.

 

[D!sco]

What's important to the extraction process is flow rate not pressure. Pressure is just the result of flow rate through a given cross sectional area and permeability. For a given machine the cross sectional area is fixed and what you control is the grind and dosage, both of which determine the permeability. Vibrational pumps and rotary pumps both deliver a fixed flow rate. Lever pistons deliver a flow rate determined by the rate of displacement. None of them deliver pressure directly.

Pressure is just flow over resistance. Expecting one to be essential without the other is missing the point. And most recipes I've liked use pressure as the variable. Flow is the determinate from having the correct resistance at the trigger for the next pressure target. Flow increases or decreases to match that target. Simple once you see it in action, really.

By George, I think you've got it. Once you start viewing the puck as "the load," the next logical step is to build an electrically equivalent model for espresso much as Thiele and Small did with loudspeaker performance.

Darcy's law already exists

Darcy's law - Wikipedia

en.wikipedia.org

As James Hoffman's CT scanner video reveals, everything coffee wants to know is solved by the oil industry already.

 

[xray]

Expecting one to be essential without the other is missing the point. And most recipes I've liked use pressure as the variable. Flow is the determinate from having the correct resistance at the trigger for the next pressure target. Flow increases or decreases to match that target.

That is completely backwards. You have confused cause and effect. Recipes use pressure because it's measuring the effect. Barring the use of a rheostat to adjust the voltage applied to the pump the flow rate is constant. Flow rate delivered by the pump does not increase or decrease to match anything. Once all the voids in the system are filled the flow rate through the puck will be constant up to the point where the over pressure valve starts to bleed off excess pressure. Even after that the flow rate delivered by the pump is constant as what doesn't flow through the puck goes through the OPV instead.

As James Hoffman's CT scanner video reveals, everything coffee wants to know is solved by the oil industry already

I have no idea what background Hoffman has but I spent 10 years in the the oil industry doing research for multi-national oil company which included running CT lab to perform high pressure flow experiments through rocks.

[edited to fix some typos]

 

[D!sco]

Oof alright man have fun. I’m sure you have valid points but this seems to be about praising your intelligence more than anything. I’m gonna keep enjoying coffee the same as I was the last six months before I posted here again.

 

[EJ3]

Coffee, yes please! Don't much care how it gets to me (I think that it would be difficult to make it badly enough that I would not drink it [unless you gave me decaff].
Otherwise, if I won't drink it, it's unlikely someone else would, either.

 

[xray]

Oof alright man have fun. I’m sure you have valid points but this seems to be about praising your intelligence more than anything. I’m gonna keep enjoying coffee the same as I was the last six months before I posted here again.

I wasn't the one to bring Darcy and Hoffman into the discussion. That was you.

 

[antcollinet]

OK, boys. It is 7:20 here, machine is up to temperature. Of to make a couple of cups. No measurements involved (except the boiler pressure guage), no equations, just my experience of the grind and the colour of the brew. And another attempt to get the milk right with the significantly higher steam production of the new machine.