# Control By Pressure Profiling versus Flow Profiling



## jzexport (Feb 6, 2019)

I am trying to understand what difference it makes in practice to the end user whether an espresso machine is flow controlled or pressure controlled.

Since pressure is proportional to flow squared, the only thing that can change is which one is the independent variable.

My impression is that most espresso machines do not allow user control of either. Some, like the Lilet Bianca allow what I believe to be pressure control. The Dalla Corte Mina offers flow control, although I am not sure if this is in real time, or if preprogrammed for a shot. The Decent Espresso DE1+ allows programming of flow or pressure, although I am not sure if changes can be made in real time. But, regardless of real time control or not, since pressure and flow are two sides of the same coin, what difference does it make in practice to the end user which one is the independent variable?

My apologies if this is an old subject, but my searching has not turned up anything succinct. Please point me to a thread, if I am wrong.

Josh


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## DavecUK (Aug 6, 2013)

Bianca is flow control via a needle valve.

I would recommend you watch the Video below, it's only 7 minutes long but covers some critically important principles. In his diagram, think of the hand valve as a gicleur (and so partly closed), the oil drum as the portafilter and the rest of the system as the pump and relief valve in an espresso machine. this gives you the basics of flow, pressure and what you are actually measuring.

The Vesuvius is slightly different in that it's a variable speed gear pump and hence does not have a constant output, but a PID controlled output. So end pressure in the system is regulated by controlling pump output directly. So if the pump in his diagram was replaced with a Vesuvius pump and the valve closed, the pump would reach whatever pressure the computer asks it to and no relief valve would be needed. With a constant displacement pump running at a set speed as in a Lelit Bianca, closing a valve would cause the pressure to build up to the maximum the pump can deliver or whatever the relief valve is set to e.g. 10 bar. Unlike in a Vesuvius where if you had a valve and closed it, if the computer was set to deliver 6 bar at that part of the phase, 6 bar is what you would get. The pump slowed down as needed to deliver any pressure required.






Arguably the Lelit Bianca and Vesuvius achieve similar results, but in different ways, the Vesuvius is the more elegant and more controllable system. I have both machines so am well qualified to judge.


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## Bolta (May 11, 2014)

Flow is the independent variable and pressure is the dependent variable.


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## Nikko (Aug 20, 2014)

jzexport said:


> But, regardless of real time control or not, since pressure and flow are two sides of the same coin, what difference does it make in practice to the end user which one is the independent variable?
> 
> Josh


You are correct about the pressure / flow relationship so it makes no difference to the stuff in the portafilter which is the independent variable if the same profile is achieved.

The Bianca uses a manually operated adjustable orifice so it is up to the user to decide which parameter he wants to prioritise, obviously bearing in mind that pressure using the gauge is easier to follow than flow.

The vesuvius control is automatic using a pressure transducer located upstream of the restrictor so not a true pressure indication at the puck.

The DE1 I believe can control automatically either on pressure (measured at the puck) or flow so like the Bianca except fully automatic and consistently repeatable.


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## DavecUK (Aug 6, 2013)

Nikko said:


> The vesuvius control is automatic using a pressure transducer located upstream of the restrictor so not a true pressure indication at the puck.
> 
> The DE1 I believe can control automatically either on pressure (measured at the puck) or flow so like the Bianca except fully automatic and consistently repeatable.


This is not really correct, he should have watched the video and learned something about fluid dynamics from it....the little bit about pascals law. Or he could have watched this June 2018.


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## L&R (Mar 8, 2018)

One more scenario is PID controlled valve after a standard vain pump(Rocket). The only downside of V I could find in term of pressure profilling is easy manual pressure control, again this is all about the software. It would be nice if I had a manual electronic paddle and a manual profile in the menu *M* just in addition to all nice features.

BR


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## Nikko (Aug 20, 2014)

DavecUK said:


> This is not really correct, he should have watched the video and learned something about fluid dynamics from it....the little bit about pascals law. Or he could have watched this June 2018.


Pascal's law applies to "confined body of fluid" as the chap in the video correctly says. In coffee making this is not normally the case as it is an open flow process. In an open flow process a restrictor such as the e61 jet causes a pressure drop and that is why the vesuvius does not control to the true puck pressure. How this impacts on the coffee making is arguable but the physics is not.

The only time the system is "confined" is when the flow is choked and then,and only then, the vesuvius would be controlling to the puck pressure for what its worth.

It is you who needs to watch the video again.


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## DavecUK (Aug 6, 2013)

Nikko when you have a Vesuvius, then you can comment, but as you don't your remarks as always are meaningless.


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## Nikko (Aug 20, 2014)

My comment was addressed to the op so he can judge its meaningfulness.

You have ably demonstrated your poor understanding of physics and despite your ownership of the Vesuvius that you do not properly understand how it works. What an arrogant and ignorant man you are.


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## DavecUK (Aug 6, 2013)

Nikko said:


> My comment was addressed to the op so he can judge its meaningfulness.
> 
> You have ably demonstrated your poor understanding of physics and despite your ownership of the Vesuvius that you do not properly understand how it works. What an arrogant and ignorant man you are.


Like I said, you don't own a Vesuvius a Lelit Bianca, or any pressure profiling machine. You don't design the machines, you don't test them, you don't review them...in fact your not helping the other person at all are you? If the other person has any sense he will ignore what you have written. Considering I helped change design aspects of the prototype Vesuvius and put it back to redesign (with my engineering advice) for 9 months, ACS must think I know what I am talking about. I don't believe ACS consulted you did they?

What you see as arrogance and ignorance, others (who matter) such as espresso machine manufacturers, roaster manufacturers and grinder manufacturers, see as experience and knowledge. Look in the mirror Nikko.


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## Obnic (Jan 14, 2014)

The way I see it....

If you're pressure controlled, the machine will expose any inadequate puck preparation by flowing quickly.

If you're *dynamically* flow controlled the machine can compensate for poor prep or puck erosion by reducing pressure to maintain the desired flow.

(John at Decent Espresso can show channels 'healing' when flow is slowed).

To me, flow control only looks like an upgrade over pressure control if it is *dynamic* ie the machine senses changes in flow and adapts to maintain the desired flow rate through the puck ie contact time.


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## Stevebee (Jul 21, 2015)

As I understand it, if you use flow control for the shot (thinking of the Decent here) and say target output of 1g per sec, the machine adjust pressure to achieve the desired flow target.

If the prep is poor or the grind way too coarse, the pressure will lower to maintain flow. So you could have a shot with perfect flow but only reach 2 or 3 bar extraction.

I tried a very very low pressure extraction on the Vesuvius early on and it wasn't good. So on the V you would adjust grind to get the desired flow/time on the Decent you would have to adjust grind to get the pressure you want to see, assuming you targeted flow. I think I've seen on YouTube a shot showing exactly this scenario where the pressure barely rose.

I think flow without the right pressure or pressure without the right flow will produce equally bad shots. Just glad on the V I ONLY have to worry about pressure, grind and profiles - that's plenty for me!


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## Nikko (Aug 20, 2014)

DavecUK said:


> Like I said, you don't own a Vesuvius a Lelit Bianca, or any pressure profiling machine. You don't design the machines, you don't test them, you don't review them...in fact your not helping the other person at all are you? If the other person has any sense he will ignore what you have written. Considering I helped change design aspects of the prototype Vesuvius and put it back to redesign (with my engineering advice) for 9 months, ACS must think I know what I am talking about. I don't believe ACS consulted you did they?
> 
> What you see as arrogance and ignorance, others (who matter) such as espresso machine manufacturers, roaster manufacturers and grinder manufacturers, see as experience and knowledge. Look in the mirror Nikko.


Appealing to higher authority by bragging about your experience does not change the fact that your understanding of how the Vesuvius works is poor. Stick to technical facts and keep personalities out of it, then we may get somewhere.


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## Nikko (Aug 20, 2014)

Obnic said:


> The way I see it....
> 
> If you're pressure controlled, the machine will expose any inadequate puck preparation by flowing quickly.
> 
> ...


Control has to be "dynamic", otherwise it is not really control. Flow is the more important parameter for the reasons you state.


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## Obnic (Jan 14, 2014)

Nikko said:


> ....your understanding of how the Vesuvius works is poor.


You do t know it but you're having a bad moment. Best to put down the spade. Dave designed and developed the Vesuvius. I reckon he might know a bit about how it works.


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## DavecUK (Aug 6, 2013)

Obnic said:


> You do t know it but you're having a bad moment. Best to put down the spade. Dave designed and developed the Vesuvius. I reckon he might know a bit about how it works.


Well I helped...


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## Nikko (Aug 20, 2014)

Obnic said:


> You do t know it but you're having a bad moment. Best to put down the spade. Dave designed and developed the Vesuvius. I reckon he might know a bit about how it works.


Is what you reckon based on faith or does it have a scientific foundation?


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## coffeechap (Apr 5, 2012)

Nikko said:


> Is what you reckon based on faith or does it have a scientific foundation?


 @Nikko you are like a dog with a bone, some fights are worth fighting and some are not, clearly you have no clue about Dave's input into the development of the Vesuvius, I doubt there is another person that knows the mechanics and componentry better than him. But if you want to keep fighting a pedantic battle carry on as it's somewhat amusing at times.


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## Obnic (Jan 14, 2014)

Nikko said:


> Is what you reckon based on faith or does it have a scientific foundation?


Not certain I understand the question. I'm an empiricist by nature.

What I can say is that I have the seventh Vesuvius made and both Paolo and Dave have supported me at every step with learning how to get the best from it and maintain it over the years. For me their expertise is a measurable fact.

Come to think of it, the ownership experience has really been quite remarkable. Not just because Paolo and Dave. Claudette and Jordan at Bella Barista have been outstanding, as have several of the CoffeeForumsUK elder statesmen - I'm thinking Ron, Xpenno and Boots particularly. A lot of knowledge was freely shared as we learned.


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## jzexport (Feb 6, 2019)

Gentlemen,

Thanks for your responses. I foolishly sent my post then got in my car and went out of town not thinking of my inability to respond.

I watched Dave's recommended videos and understand.

I notice that Dave seems to use flow control and pressure control interchangeably. Regardless, and perhaps I do not know the language because I am new to espresso, but to me flow profiling means achieving a desired flow vs time curve measured close to the puck or it's output, with the flow controlled by varying the upstream pressure ala the manual valve in the diagram or via a pump with variable output pressure or via pump .

Pressure profiling means achieving a desired pressure vs time. The pressure could be controlled in the same way as flow control.

One question I think unanswered was what difference does it make in practice? Probably not.


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## dev (Jul 28, 2017)

When you realize "profiling" is just another overused buzzword, it's actually quite refreshing.

Without an active feedback loop that compensates whatever happens with the coffee puck once its fully saturated, current machines just run a predetermined script.

I'm not so sure DE machines have a pressure sensitive feedback algorithm.


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## rytopa (Jul 18, 2017)

Dave could you do a video of the vesuvius led display panel while running a pressure profile but without any portafilter inserted. I am curious to know if the machine reads the pressure off the puck or upstream.


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## Nikko (Aug 20, 2014)

Obnic said:


> Not certain I understand the question. I'm an empiricist by nature.
> 
> What I can say is that I have the seventh Vesuvius made and both Paolo and Dave have supported me at every step with learning how to get the best from it and maintain it over the years. For me their expertise is a measurable fact.
> 
> Come to think of it, the ownership experience has really been quite remarkable. Not just because Paolo and Dave. Claudette and Jordan at Bella Barista have been outstanding, as have several of the CoffeeForumsUK elder statesmen - I'm thinking Ron, Xpenno and Boots particularly. A lot of knowledge was freely shared as we learned.


Discussion was about how the vesuvius measures pressure and how those measurements correlate with the pressure at the puck. Glad to hear you have had good service which clearly trumps trumps any meaningful discussion.


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## DavecUK (Aug 6, 2013)

rytopa said:


> Dave could you do a video of the vesuvius led display panel while running a pressure profile but without any portafilter inserted. I am curious to know if the machine reads the pressure off the puck or upstream.


There would be no point doing that, it won't tell you anything useful because it's an objective based system, PID controlled (pressure) with a gear pump that's capable of quite a high flow rate. So if you program in 9 or 10 bar, it will try and achieve it....pumping more fluid as required....equally as the pressure builds (say against a static load), it will reduce flow (to 0 if need be), again to achieve the target pressure requested.

e.g. If there is a puck with significant resistance and machine is set to 10 bar, it might push through 50ml per minute, if the puck fractures and resistance drops, the pump will simply increase output to maintain the pressure.

The Gicleur size has been carefully chosen to work well in a range of situations, I did have some other things I would have liked to see on the Vesuvius, but they will have to wait and I would imagine ACS would want to copyright the ideas.



jzexport said:


> I notice that Dave seems to use flow control and pressure control interchangeably. Regardless, and perhaps I do not know the language because I am new to espresso, but to me flow profiling means achieving a desired flow vs time curve measured close to the puck or it's output, with the flow controlled by varying the upstream pressure ala the manual valve in the diagram or via a pump with variable output pressure or via pump .
> 
> Pressure profiling means achieving a desired pressure vs time. The pressure could be controlled in the same way as flow control.
> 
> One question I think unanswered was what difference does it make in practice? Probably not.


In a "sense" this is correct, they both achieve pressure control, but by using different metrics for feedback. In practice it makes little difference, but there are differences. e.g. against a static load, or near static load (chocked puck), the rate of pressure drop (if any is requested) is directly proportional to the permeability of the puck when using a fixed displacement pump with (needle) valve control. When using a gear pump, pump output drops as it senses this (assuming the control system is fast enough) and the pressure on the system is more effectively reduced. The effect is subtle and arguably if a valve had a good computer control system, then it might be able to achieve similar results. The issue then is really how fine the control of such a valve is vs a gear pump which has a VERY fine level of control.

You can't really have flow and pressure controlled simultaneously by design, they are both variables anyway. You need to decide which one you will use for feedback, because changing one affects the other. When I read the so called "puck healing" stuff I smiled a little, because changing the dynamics of the machine in response to a fractured puck is shutting the door after the horse has bolted. The train of great coffee left the station and running after it won't get you on board.

For me the V delivers in a few areas, but as I say, I also own a Lelit Bianca and a Duetto and a ....

1. Programmability/repeatability

2. Construction

3. Temperature stability/Accuracy

With coffee technology, it's difficult for the community to get a good grasp of what really happens in the development process of a machine, there are some "interesting" if not entirely correct views, some of them actually held by manufacturers. I'm really interested in seeing things move forwards, but over time my views have changed. It's not all about technology and whizzy little functions. These are just code, cheap to add and often gimmicks. Things are better when they are simple and simply work without the user having to think about them. I'd like to see better machines at cheaper prices as I think it's another area that has got totally out of control...making good coffee an elitist pursuit has never been of interest to me, I prefer to see it more accessible.


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## Obnic (Jan 14, 2014)

jzexport said:


> One question I think unanswered was what difference does it make in practice? Probably not.


I'm not sure that I'm getting to the heart of your question but...

I bought into a pressure profiling capability because I wanted to increase extraction yield without excessively diluting my shot.

My thought was to manage contact time between water and coffee - initially increasing that time as the shot progressed and it became harder to leach the remaining oils.

There's a rabbit hole here because you want some of those oils (sweetness) but not others. This led to a lot of experimentation with long preinfusion and lower pressure shots (6 bar).

Ultimately, I found that using a predetermined pressure profile, my puck prep (which is good) became a real variable. Weighed doses to weighed output take different amounts of time, and measure different EY, and so taste different.

This is not a huge problem. I still love the drinks. The V still makes much better coffee than my previous flat profile Leva Dual Boiler. However, I was in my white coat refractometry stage and not being able to lock out the variation was frustrating.

When Decent Espresso showcased their dynamic flow controlled DE1+ I thought this must be the solution. Here at last was a machine that directly controlled contact time not through the proxy of pressure.

In that sense, it is the step on from a pressure profile. I suspect you really can focus your extraction of flavours (oils) based on a better understanding of how the puck for 'coffee A' dissolves.

But I haven't bought the machine.  However fascinated I am by the thread. The rabbit hole described above became fatiguing. I remember just really enjoying a shot one day, making another, and consciously thinking 'god I've missed this'. I then went through a prolonged phase of making Sowden steeps and Chemex drinks. I'm back with espresso.

So in summary, for most people, I think flow profiling will be about consistency. It will compensate for their average puck prep. For some, it will be white coat refracting heaven. These are the coffee equivalent of the oenologists. They will be able to tune their extraction to get the perfect expression of each coffee. But for me 'madness that way lies'.


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## Nikko (Aug 20, 2014)

DavecUK said:


> There would be no point doing that, it won't tell you anything useful because it's an objective based system, PID controlled (pressure) with a gear pump that's capable of quite a high flow rate. So if you program in 9 or 10 bar, it will try and achieve it....pumping more fluid as required....equally as the pressure builds (say against a static load), it will reduce flow (to 0 if need be), again to achieve the target pressure requested.
> 
> e.g. If there is a puck with significant resistance and machine is set to 10 bar, it might push through 50ml per minute, if the puck fractures and resistance drops, the pump will simply increase output to maintain the pressure.
> 
> ...


There you have it from the horses mouth - the Vesuvius controls pressure from a transducer located up stream of the gicleur so controls the pressure at the gicleur and not at the puck. Which is exactly what I said in post 4 and which DaveC condescendingly denied in post 5, referring to Pascal law which does not apply but confuses and impresses the masses. Why is he trying to confuse?

Regarding the point about how the different types of control respond to the puck dynamics, "flow" control such as in the DE1 works to counteract the effect of changes in the puck resistance so can be thought of as "self correcting", whereas "pressure" control as in the Vesuvius will actually make the problem worse, i.e. a fast flowing puck will flow even faster, choking puck will choke more. As people struggle to achieve consistency of puck preparation, the self correcting nature of flow control can't be a bad thing.

For me, flow is the more important parameter in the extraction process. Using pressure to approximate flow is a round about way of going about it and the reason it is done is because pressure transducers are simpler than flow transducers.

The bit comparing variable speed pumps with needle valves is incomprehensible waffle. No wonder there is so much confusion about.


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## DavecUK (Aug 6, 2013)

Nikko said:


> There you have it from the horses mouth


Nikko, I don't want to be rude (although I am tempted to make an exception specially for you). I'll just wait for the likes for your posts to roll in, then I'll wait (a lot longer), for you to actually say something useful. I fail to understand why you jump on everything I say, I certainly ignore most of what you say as unimportant and have no wish to discuss details with you or try to give explanations to your fallacious points. The perfect machine for you would be the DE1 pro or plus whatever....then you could disappear (substitute a ruder word here if you want) off back up your own arse and play with a machine that seems to impress you and would remove your need to ever comment or consider anything else.

In fact why not write a review on something so you can benefit the community with your knowledge, or approach some manufacturers to assist them with designing a machine, roaster or grinder. I'll bet they will be overjoyed to hear from you. I think you might have burnt your boats with Niche, but I am sure Mazzer and Ceado would love to hear from you. Or perhaps Decent Espresso would value your input, maybe Toper, Dalian or Bella Barista...or are you too busy. *What was it you did for a job*, if unemployed, then you have lots of time on your hands? Someone with your knowledge has so much to give...you should spread it around especially to people other than me.

Yours Cordially

DaveC


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## dev (Jul 28, 2017)

Only a truly small man resorts to name calling and insults when he runs out of arguments. Maybe that's a side you should've kept hidden, DaveC.


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## DavecUK (Aug 6, 2013)

dev said:


> Only a truly small man resorts to name calling and insults when he runs out of arguments. Maybe that's a side you should've kept hidden, DaveC.


If you say so, but i think I have put up with enough from him.


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## coffeechap (Apr 5, 2012)

dev said:


> Only a truly small man resorts to name calling and insults when he runs out of arguments. Maybe that's a side you should've kept hidden, DaveC.


 @dev How can it be true if they are 6ft 4 ?


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## L&R (Mar 8, 2018)

Mods alert:yuk:


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## dwalsh1 (Mar 3, 2010)

L&R said:


> Mods alert:yuk:


Spoilsport


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## Stanic (Dec 12, 2015)

Obnic said:


> If you're pressure controlled, the machine will expose any inadequate puck preparation by flowing quickly.


this is certainly very true for the Portaspresso, if the puck is not perfect, the shot is ruined instantly after applying pressure (be it from the air cylinder of the PG Air or via cranking down the piston with the HC-P)


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## jzexport (Feb 6, 2019)

Obnic,

Thanks for your thoughtful response. I am just trying to educate myself, especially for when I move on from my Barista Express. My main goal is consistently good, non-milk coffee. I am horribly struggling with consistency and not having fun. Roasting has been fun, even on a Behmor. Espresso has not. I put up a thread on that, today. Flexibility to try different kinds of shots is also desirable. I recognize the risk of going down the rabbit hole. I don't see myself with a refractometer.

Davec,

I suspect you dislike the Decent Espresso. Why? I take it you enjoy the hands on of the Vesuvius and Bianca, and not the drawing of profiles in software and pressing go of DE. I admit, I am torn on that, too. But, there seems to be more to it than that for you when it comes to the DE, Nikko aside.

Josh


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## Bolta (May 11, 2014)

Since you're interested in espresso only and you are also interested in profiling, have you considered a Strietman CT-1. It's an open boiler machine and a manual lever, which puts you in complete control of pulling a shot.


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## jzexport (Feb 6, 2019)

Bolta,

I'll have to check it out. Never heard of it. But, my wife likes the milk drinks.


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## DavecUK (Aug 6, 2013)

jzexport said:


> Davec,
> 
> I suspect you dislike the Decent Espresso. Why? I take it you enjoy the hands on of the Vesuvius and Bianca, and not the drawing of profiles in software and pressing go of DE. I admit, I am torn on that, too. But, there seems to be more to it than that for you when it comes to the DE, Nikko aside.
> 
> Josh


I think you are assuming too much based on insufficient information. I've extensively tested so many different machines, it gives me a perspective/experience of them very few people have. I've considerable experience of machine design as well

Ultimately people get the machine that best presses their buttons for whatever reasons. Ultimately whatever you buy you will like it because it's your choice. Many different people on the forum will advise you and you simply have to weigh the comments against their experience and your needs or desires.


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## Mrboots2u (May 10, 2013)

I hope grandpa Dave and cousin Dev make it up for Xmas .


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## DavecUK (Aug 6, 2013)

Mrboots2u said:


> I hope grandpa Dave and cousin Dev make it up for Xmas .


Bootsie, If dev thinks it's appropriate for Nikko to keep on and on hassling me with me saying nothing, then his opinion means very little to me and his approval, or not, of my actions isn't really a concern for me.







"Good is as good does" I think is what they say.


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## jzexport (Feb 6, 2019)

DaveC.

I didn't mean to put words in your mouth. It seems like I stumbled into an ongoing conversation between you and Nikko and jumped to premature conclusions.

Josh


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## DavecUK (Aug 6, 2013)

jzexport said:


> DaveC.
> 
> I didn't mean to put words in your mouth. It seems like I stumbled into an ongoing conversation between you and Nikko and jumped to premature conclusions.
> 
> Josh


I know, it's easy to get confused...and it's not ongoing, just continual on anything and everything I say.


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## dev (Jul 28, 2017)

It's easily to get confused if one doesn't understand how influencers work. And how manufacturers use said influencers.


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## PaulL (May 5, 2014)

dev said:


> It's easily to get confused if one doesn't understand how influencers work. And how manufacturers use said influencers.


I don't understand what that mean Dev, can you expand on it?


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## Nikko (Aug 20, 2014)

DavecUK said:


> Bootsie, If dev thinks it's appropriate for Nikko to keep on and on hassling me with me saying nothing, then his opinion means very little to me and his approval, or not, of my actions isn't really a concern for me.
> 
> 
> 
> ...


I also do care that you do not care about my opinions, however, in this case I did not express an opinion but made a factual statement which you dismissed in a rather arrogant fashion but admitted later that it was correct. In the process you also revealed your poor understanding of science. By trying to deny something which is true, it is fairer to say that you are hassling me.

You being the UK marketing department of ACS (and others), I can understand that you may not want people to know certain things about their products but it does not sit well with your oft repeated claims of honest and independent advice, particularly when you deny factual truths. No product is perfect and I believe it is one of the purposes of this forum to learn and to get a better understanding.

In the eyes of those that see through this you are losing credibility!


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## Mrboots2u (May 10, 2013)

Neither of you care about each other opinions so perhaps just leave it at that and don't post to each other. You are not going to agree, I'm not being sarcastic but half of us don't probably even understand the points you are trying to make. @Nikko, I'd suggest you stop casting aspersion about some one being in the pay of a company/companies when they are not.

People can make their own minds up from these posts about who has credibility etc.


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## The Systemic Kid (Nov 23, 2012)

Don't want to step in and have to mod this thread - the OP is very interesting and relevant. Please refrain ad hominem attacks and stick to the facts/physics.


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## Obnic (Jan 14, 2014)

jzexport said:


> I am horribly struggling with consistency and not having fun.... I don't see myself with a refractometer.


Oh boy can I relate.

We spend a lot of time talking about weighing but in my book the first and most important thing to get right is puck building. All consistency stems from this.

Naked PF and VST baskets are essential in my view for ruthlessly exposing all your flaws. Even then over tamping can result in puck lamination which can still look like a good pour.

A good grinder becomes important for delivering fluffy, non-static grind. But even then distribution in the PF before tamping is an art one must master.

And don't get me started on tamper base profiles and level tamping. Finally, now I use a push tamper i think I've cracked this.

You'll know your puck building is right when you have to loosen your grind, and at last your pour times become consistent for a given ratio.

You may well have mastered this, in which case you're a better man than me gungadin. For me puck building is a zen-like quest for elusive perfection - but that's part of the joy.

Refractometry - never say never, it's fascinating.


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## Mrboots2u (May 10, 2013)

@jzexport Refract wont help with consistency , just tell you how inconsisitent you are being . Presumably your mouth tells you when the shot is good....

It can provide a roadmap of adjustments to extraction though if you are unsure where you are .

By chance you are not using a 15g vst are you


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## ajohn (Sep 23, 2017)

I only read some of this thread due to another.

Sometimes this sort of thing crops up in other areas. One person may do one thing and some one else may do something else. One may feel theirs is the only way.

Here the "debate" in some ways relates to semantics - after a fashion.

Pressure laws are pretty simple. All parts of a sealed system will be at the same pressure at some point as it's pumped up to it. Some point because of what happens when there is flow. It meets resistance so pressure is lost. This is a fact but it's not possible to look at something and gauge the effect it will have. Sums are available but for a whole variety of reasons aren't accurate and of course the pressure losses increase with flow rates.

An espresso machine adds a None Linear Variable Restriction to the flow - the puck. All machines have some form of pressure control driving the water through it even if it's just the pump and the pressure that can reach on a few will only be limited by the puck or by it stalling.

What people do on an espresso machine is play around with this NLVR to achieve a desired result in terms of taste or (unfortunately) some rules they have read about on the web that boil down to some in to out ratio over some time period. Tuning in other words.

So yes physics are involved in flow but in a sense don't matter as what ever used it's tuned to suite. Some methods will provide a more consistent pressure to feed the fluid through than others. When that pressure is measured is some one going to use something that can read to a uBar or less or something like a typical machine brew pressure gauge. I'd hope they don't use the later as going on ones I used before buying a proper gauge they are non linear at some point probably to prevent them from breaking if overloaded.

One thing some one can't do is look at a system from afar and make assumptions about what a restriction will do. To "amuse" coffechap I'll give an example where the restriction can have a huge and in some cases unexpected effect. I have an air rifle. A reservoir is charged to 200bar. Away from the UK it will generate 30ft lbs of energy into a pellet. In the UK a restricter is fitted to reduce it to 12 to meet legal requirements. It's surprisingly consistent and wont go above that. There is a gent about who will modify this pretty marginally. Net result. The first 12 shots will be at 12ft lbs. There after 18. In this case the restriction is controlling the velocity of air in the barrel.

Many machines use vibratory pumps. A piston pushes out a volume of water each time it vibrates usually up to a max pressure of 15bar at which point it stalls. Infusing just means "slowing down" the rate it vibrates at reducing flow.

Over pressure valves on espresso machines are pretty crap in terms of maintaining precise pressures but we don't notice. The reason for that is that they need to open more to accommodate higher flow rates and they are working against a spring. The system used on rotary pumps is unlikely to be any different - nice though due to less noise.

Going back to the OP. Is flow or pressure profiling better? I'd hazard a guess that in practice there is little difference as both are aimed at controlling flow rates based on what they meet at the end which can be varied. In some way the ability to adjust them is a nightmare - too many variables. Take my DB for instance. I can adjust the flow rate and the time. So buy a kg of beans, use a random balance approach and taste and pour down the sink all day. Then do the same with another bean even if previously I didn't like it as it might turn into the best drink I have ever had?

John

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## Syenitic (Dec 1, 2013)

ajohn said:


> I only read some of this thread due to another.
> 
> Sometimes this sort of thing crops up in other areas. One person may do one thing and some one else may do something else. One may feel theirs is the only way.
> 
> ...


phew!


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## ajohn (Sep 23, 2017)

Syenitic said:


> phew!


What's wrong,







don't to you like the idea of calling a puck a NLVR. Both protagonists are correct to some some degree.








Both should consider the uncertainty principle as it relates to how close something is measured and maybe even Schoeder's cat as they can't see in the puck or measure all pressure every where even in a simple machine.

LOL I thought it might be worth simplifying some terms used too.

John

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## ashcroc (Oct 28, 2016)

ajohn said:


> What's wrong,
> 
> 
> 
> ...


Who is Schoeder's cat?


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## Syenitic (Dec 1, 2013)

ashcroc said:


> Who is Schoeder's cat?


It is a thought experiment that lives inside of aJohns head. But no one knows if it is real or not!


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## ashcroc (Oct 28, 2016)

Syenitic said:


> It is a thought experiment that lives inside of aJohns head. But no one knows if it is real or not!


Ah. Guess he must've plagerised Schrödinger!


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## Mrboots2u (May 10, 2013)

ashcroc said:


> Who is Schoeder's cat?


He is Garfield s best mate


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## The Systemic Kid (Nov 23, 2012)

ashcroc said:


> Who is Schoeder's cat?


You mean Schroeder's cat. Think it was called Pascal.


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## Syenitic (Dec 1, 2013)

The Systemic Kid said:


> You mean Schroeder's cat. Think it was called Pascal.


No it was clearly called Paradox, as can be seen here from IFLScience.com [https://www.iflscience.com/physics/schr%C3%B6dinger%E2%80%99s-cat-explained/] :

This video from Sixty Symbols does an excellent job at explaining the Shrödinger's Cat Paradox:


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## The Systemic Kid (Nov 23, 2012)

The Schroeder's cat in this thread is definitely called Pascal


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## Drewster (Dec 1, 2013)

I always though Schroeder had a piano......

The closest thing to Schroeder's cat I can think of is.... Snoopy!!!!


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## Syenitic (Dec 1, 2013)

Drewster said:


> I always though Schroeder had a piano......


No that was Les Dawson or Liberace or some other geezer, cartoons don't count outside the imaginarium.


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## Hasi (Dec 27, 2017)

It's Schrödinger. As in Schrödinger.

The good thing is, nobody can argue against that and be right at the same time.


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## ajohn (Sep 23, 2017)

Hasi said:


> It's Schrödinger. As in Schrödinger.
> 
> The good thing is, nobody can argue against that and be right at the same time.










No the cat is dead. Spent so long deciding about what state it was in it died through lack of food and water. Maybe even asphyxiation as there was no way of seeing what was inside and the size of the case wasn't specified. It might not even have been put in there.

Not a good thought experiment. Eistien's lift shaft one is much better.

John

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## Syenitic (Dec 1, 2013)

who is Eistien?


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## ajohn (Sep 23, 2017)

Syenitic said:


> who is Eistien?


https://www.google.com/search?client=firefox-b-d&q=Eistienasphyxiation

John

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## Hasi (Dec 27, 2017)

Google said it didn't find anything but never mind. He that is without sin, let him cast one stone...


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## jzexport (Feb 6, 2019)

Obnic,

I started a thread on my inconsistent shot times, and didn't mean for that topic to contaminate this thread. But ...

I don't have a naked portafilter or VAT basket. That will have to wait for my moving on from my Barista Express.

I suspect apart from the grinder, that puck prep is where it's at, as you suggest. I have learned, for sure, that the grinds are sensitive to being disturbed. I wonder why people that shake the grounds, vigoursly WDT, and finger smooth, etc, do not have repeatablity problems. i am trying to not disturb the grounds, other than mild WDT for clumps, and doing everything the same, and still have large variation in shot time. Wish I knew where I was messing up.


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## Obnic (Jan 14, 2014)

jzexport said:


> Obnic,
> 
> I started a thread on my inconsistent shot times, and didn't mean for that topic to contaminate this thread. But ...
> 
> ...


I have a brilliant tool. It's a plastic clay shaping spatula (rather like a lolly stick) with a straightened paperclip taped to one end.

My prep is invariably a version of this routine: (1) grind fluffy pile directly into basket, (2a) tap portafilter side gently on palm of hand to level the fluffy pile of grounds, (2b) if coffee is binding or not distributing evenly WDT with paperclip to ensure even *density* of grounds at all points in basket, (3) use side of clay spatula to level and ensure even *depth* of grounds at all points in basket especially at edges, (4) tamp level and relatively lightly (not 30lbs).

My clay spatula is wider than the basket so it levels to exactly the rim of the basket across the whole puck. I find this much more consistent than using fingers to level.

If my chosen dose means the coffee is below the rim before levelling I use a smaller basket. If it's abover the rim, I use a bigger basket. This does rather require a fluffy pile of grounds though ie a good grinder.

Mistakes I have become sensitised to include:

Uneven density before tamping.

Uneven depth (around the rim particularly)

Profiled tamper bases (they can seal edges better if your distribution is off but they create a dense patch in the middle of your puck)

Non level tamping (even possible with a push)

Over tamping leading to puck lamination

I have installed a mirror on my drip tray so I can watch the bottom of the basket. I want coffee to appear simultaneous in all basket holes; I then want the coffee to cohere almost immediately into a single central steam. It doesn't always play out that way!!


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## DavecUK (Aug 6, 2013)

Obnic said:


> ; I then want the coffee to cohere almost immediately into a single central steam. It doesn't always play out that way!!


I am going to ask why to this statement?


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## Obnic (Jan 14, 2014)

DavecUK said:


> I am going to ask why to this statement?


Fair challenge - my poor drafting. What I mean is that I don't want multiple mouse tails around a dry centre of the puck. I'm expecting a single tail nice and central.


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## ajohn (Sep 23, 2017)

jzexport said:


> Obnic,
> 
> I started a thread on my inconsistent shot times, and didn't mean for that topic to contaminate this thread. But ...
> 
> ...


The thing about the Barista Express is that the shot time will vary mostly down to what the user does to the grinds. Get that right and the shot time will hardly vary at all even though there are still a certain level of variation in the puck. Get this right and you are likely to suffer a bit of culture shock when you do upgrade.

John

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## DavecUK (Aug 6, 2013)

Obnic said:


> Fair challenge - my poor drafting. What I mean is that I don't want multiple mouse tails around a dry centre of the puck. I'm expecting a single tail nice and central.


I realise this always is a stated objective, why do you believe it should be central at or close to the start after it sweats out all of the holes? I have noticed over the years: On a pressure profile machine with a slow low pressure start and ramp, it takes longer for the streams to coalesce and it tends to happen as the pressure (hence flow increases) and on a non profiling machine the streams coalesce much faster.

I do like to see it sweat across all the holes at a similar rate so the whole bottom of the portafilter is evenly brown...but even then I don't know if that's preferable to sweating almost at the same rate, but from the centre in. I just like to see the former rather than the latter.


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## Obnic (Jan 14, 2014)

DavecUK said:


> I realise this always is a stated objective, why do you believe it should be central at or close to the start after it sweats out all of the holes? I have noticed over the years: On a pressure profile machine with a slow low pressure start and ramp, it takes longer for the streams to coalesce and it tends to happen as the pressure (hence flow increases) and on a non profiling machine the streams coalesce much faster.
> 
> I do like to see it sweat across all the holes at a similar rate so the whole bottom of the portafilter is evenly brown...but even then I don't know if that's preferable to sweating almost at the same rate, but from the centre in. I just like to see the former rather than the latter.


I think we're agreeing. Yes, takes longer to coalesce with a lower pressure and slow ramp. And, multiple tails or a tail off to one side is usually indicative of a channel.

Granted though, it's an assertion that simultaneous appearance of coffee in all holes is better than appearance in ring around outside, which then stalls whilst centre catches up. My belief (rather than certainty) is that the ring is a function either of my failure to seal sides adequately or lower density at sides.

I reached this conclusion because the outer ring phenomenon appeared when I switched from convex to flat tamper base. I surmised (though I'm open to challenge - strong ideas, lightly held) that this was because of a fault in my puck build at the edges. When I concentrated on this, I cured the ring. When I switched back to convex I got a ring because I was effectively tamping the centre more than the sides. This seemed to confirm my thinking but I'm no fluid dynamicist. I freely steal wisdom from smarter folk on the forum - not least you mate







as you well know.


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## ajohn (Sep 23, 2017)

Obnic said:


> I have a brilliant tool. It's a plastic clay shaping spatula (rather like a lolly stick) with a straightened paperclip taped to one end.
> 
> My prep is invariably a version of this routine: (1) grind fluffy pile directly into basket, (2a) tap portafilter side gently on palm of hand to level the fluffy pile of grounds, (2b) if coffee is binding or not distributing evenly WDT with paperclip to ensure even *density* of grounds at all points in basket, (3) use side of clay spatula to level and ensure even *depth* of grounds at all points in basket especially at edges, (4) tamp level and relatively lightly (not 30lbs).
> 
> ...


I'd worked a routine with my Mazzer Mini that worked. Similar is some respects. Nice pile of fluffy grinds always in the same central place in the portafilter , I added stops to the rest to achieve that. Then part tamping with a chisel groomer. Then a calibrated tamper that I happened to have. Early on I intended to turn it down to suite my previous machine but didn't. I found that helped a bit. As I took it apart it's set at 15kg so on the light side of things. Later based on people buying oversized tampers I started polishing with a small amount of pressure with the tamper offset so that the edge always touched the side of the basket. A small improvement in variation over lots of shots.

So several days at 3 a day with variations of output of circa 1g often less and then the grinder strikes. No R in the month, phase of the moon, weather, bean age. At some point time to adjust the grinder. The main culprit seemed to be bean age. Adjustments nearing the end of the can maybe needing to go back a bit on the next can from the same roast batch. Have to allow some drift from ideal due to problems making tiny adjustments to the grinder and always using a preset 30sec shot time extended up to a max of 35sec before adjusting. Also some latitude on the shot size I tune for again due to grinder adjustment and using a fixed 30sec shot.

Pours. Mixed. Sometimes one stream straight away. or more usually 2 during infusion quickly switching to one.

Used puck - turn the portafilter over and it falls out leaving nothing behind except a bit around the rim due to the way I have polished.







That probably isn't possible with all beans - in fact I know it isn't.

Behind all of this I do know how much variation is ok as far as actual taste goes so some aspects are academic. All with a basket that is similar to a 15g VST but shallower and holding less coffee. Flow with an 18g basket is generally better.

John

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## Syenitic (Dec 1, 2013)

ajohn said:


> I'd worked a routine with my Mazzer Mini that worked. Similar is some respects. Nice pile of fluffy grinds always in the same central place in the portafilter , I added stops to the rest to achieve that. Then part tamping with a chisel groomer. Then a calibrated tamper that I happened to have. Early on I intended to turn it down to suite my previous machine but didn't. I found that helped a bit. As I took it apart it's set at 15kg so on the light side of things. Later based on people buying oversized tampers I started polishing with a small amount of pressure with the tamper offset so that the edge always touched the side of the basket. A small improvement in variation over lots of shots.
> 
> So several days at 3 a day with variations of output of circa 1g often less and then the grinder strikes. No R in the month, phase of the moon, weather, bean age. At some point time to adjust the grinder. The main culprit seemed to be bean age. Adjustments nearing the end of the can maybe needing to go back a bit on the next can from the same roast batch. Have to allow some drift from ideal due to problems making tiny adjustments to the grinder and always using a preset 30sec shot time extended up to a max of 35sec before adjusting. Also some latitude on the shot size I tune for again due to grinder adjustment and using a fixed 30sec shot.
> 
> ...


alternatimodal....https://www.youtube.com/watch?v=R2nI_3VBEtA


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## Rob1 (Apr 9, 2015)

I had a perfect pour today, sweating evenly across the basket and forming one thin stream in the middle. It didn't taste any different to yesterdays that took a few seconds to form a single stream after two that began just off centre. I doubt the appearance of a perfect pour really makes all that much difference, but I can taste when I've had a hard time distributing the grinds and the streams begin off to one side and only form in the middle towards the end of the shot (occurrences were thankfully rare and shouldn't happen now I use a chisel style tool).


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## jzexport (Feb 6, 2019)

ajohn said:


> The thing about the Barista Express is that the shot time will vary mostly down to what the user does to the grinds. Get that right and the shot time will hardly vary at all even though there are still a certain level of variation in the puck. Get this right and you are likely to suffer a bit of culture shock when you do upgrade.
> 
> John
> 
> -


I will just have to work harder on my puck prep. What is the bit of culture shock I will get when I upgrade?


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