Hi All,

I do really appreciate the effort the HB community puts forward in actively participating in finding solutions and improvements for the betterment of the espresso machine user and managing one of the parameters (temperature stability) to repeat the desired holy grail, especially with regards to temperature stability.

I would like to 'chime in' on one important factor from the business side and the technical side. Although I am making a general and bold statement, I do want espresso machine owners to realize that I have not found the holy grail to perfect temperature stability on many espresso machines for every usage scenario.

I have tested many machines (including ones we do not sell) under $3k using a data logger that records temperature stability across 16 different thermocouples cemented to 16 different locations with recordings up to 1/100th per second in each thermocouple. This data logger had cost close to $4k and is actually used in some nuclear power facilities to monitor temperature.

I have even tried to replicate results of what I have found online, have tried different testing scenarios/procedures, and I have difficulty replicating a lot of those results. In some cases, customers have emailed me results that seemed perfect using different tools on machines they bought from us, and I had still a difficult time replicating. In different words, I will find a usage pattern or lack of a pattern to find a delta in any machines capability in managing temperature stability on any espresso machine. I have even changed variables to find the delta (ie drafts, ambient temps, voltage, etc).

The reason for my post is that there are sometimes posts about design flaws or defect with a(ny) machine because of a delta in temperature in a certain scenario. From the business side, it is not a flaw or defect.... If a reseller or manufacturer explicitly stated a certain performance of temperature stability without any statement that results could differ, then I would agree that there is false advertising, a design flaw, and/or a defect. However, manufacturers design different espresso machines at different price points which include different designs and features that accentuate different results with regards to the 'resulting' performance of an espresso machine. One of those results being temperature stability.

This post is not to create any controversy, but MAINLY to just keep a level understanding of what and how manufacturers offer at each price point when researching, designing, and producing their machines. In other words, for those seeking a double boiler machine or other styled machine for superior temp stability, you 'may' not be able to achieve the same exact results as your neighbor next door with the same machine.

The secondary purpose of the post is to find out if others have a difficult time replicating results posted by others online and what is believed to cause the different impact in layman's terms. As you can see, I am not pointing any fingers to any particular machines and I hope followup posts remain the same as we nor any poster should disparage any machine in the marketplace. In other words, I would like to not to be machine specific but am looking for members who have had recorded different results from they see online posted by others.

Finally, keep up the good work on HB as many topics have been quite an enjoyable read.

Great Post.

I'd like to just briefly mention that I've pretty much stopped trying to replicate others results because of pretty much everything you just said. It has freed me from a lot of frustration.

And I do not believe there will be any Holy Grail. There comes a point where the amount of energy being put into it stops coming across in the cup... I may be surprised in the future though on this, so I'll be keeping an open mind.

1st-line wrote:... I have even changed variables to find the delta (ie drafts, ambient temps, voltage, etc).
...

It sounds like you're aware of many of the factors that could affect this issue. The usual lack of ambient conditions, lack of usage pattern (of the portafilter and the machine) and other less obvious nuances led me, early on, to suspect that maybe machines with a saturated group (not many under $3K) could sometimes demonstrate repeatable results, but machines without a temperature-controlled group were much too vulnerable to outside factors (environmental and process). So, like baristalab, I didn't even try to replicate others' parameters/performance.
-Ed

I think that trying to replicate temperature between machines in different places is futile because of environmental factors alone.

More important thing is repeatability of temperature/profile on same machine and that is what I would call temperature stability. If temperature profile on a given machine can be reliably repeated I think you can say you have temperature stability.

1st-line wrote: but am looking for members who have had recorded different results from they see online posted by others.

A very sensible post. What about the home barista future (or present) of systems that can monitor and adjust multiple inputs online for people who own the same machine?

I have owned a number of machines - a number of them were E61s.
Each had their own personality.
Some were infinitely easier to pull a near-god shot on, than others.
I can hypothesize as to why, but don't really know.

A perfect machine would need mass - perhaps a spherical boiler(water circulated, of course), with a sphere within that holding at least x cups of water- preheated to extraction temp for brewing(also circulated)(fed from the outside from a preheated source, and within all that, a miniscule group and extraction area, with a tube with the extracted liquid finding it's way back out through the layers.

Mass is fine, but distance from boiler is a killer, especially with more than one shot pulled. 1. Reduce that distance to zero, and you have a fine machine. 2. Preheat water coming in and you have a better machine. 3. Enlarge the boiler and it improves.

Every time you introduce water of a different temperature, you screw up the whole system. The direction seems to be "build a massive enough machine and it won't matter". So the result is many different machines built on the same basic design, all with non-compatible parts.

Not having a machine shop handy, I buy a commercial machine which is at the right price/capability point for me at that moment. And then learn it's capabilities.

I agree with Tekomino's implicit differentiation of temperature profile and temperature stability, and likewise his suggestion that we think in terms of repeatability rather than stability. The notion that flatline stability generates a better shot has been comprehensively demolished here on HB just as it was when Naples fell back in love with lever machine some decades prior....

I don't think there is any one holy grail for temperatures as long as it has a reasonably delta. Reasonable to me is a degree to degree and a half. Then there is the entire temperature curve argument. Which is better, a humped temp curve, flat, inclining, declining, bell? Again, I do not think one is right and the rest are wrong, simply different. I think this post from another thread sums up my feelings on temperature

cannonfodder wrote: I think folks get too caught up in temperature measurements. It is one of the few things that can be measured relatively easy so we tend to focus in on that. Personally, I think there are many other factors just as important as or more so than uber flat temperature profiles. As long as a machine produces a reasonable temperature profile, the key is the ability to reproduce those temperatures. You can do a lot on a HX machine to tweak the temperatures. You can add flow restrictors to the thermosiphon, change the pressurestat, change the injector tube in the heat exchanger, change the ambient temperatures around the machine, etc... I have used PID controlled single boilers, heat exchanger, steam pressurised levers, etc... and they all produced good shots, just different. It is just a matter of learning the nuances of you kit and that only comes with time and experimentation.

My guess is at some point in the future stability/control will no longer be significantly managed by mass of metal/water. That it will go in the opposite direction with low mass and advanced technologies of fast acting heating and electronic controls.

farmroast wrote:My guess is at some point in the future stability/control will no longer be significantly managed by mass of metal/water. That it will go in the opposite direction with low mass and advanced technologies of fast acting heating and electronic controls.

As in the new Rancilio Xcelsius, demonstrated in Houston this month: http://www.rancilio.com/rancilio/news_detail.jsp?id_cat=3&id_news=454&id_language=3.