Have you mastered the espresso machine variables?

[Tex]

Howdy Folks,
I don't care which espresso machine you have, or how much you paid for it, there are just two machine variables to manage. Get both under control and you're on your way to coffee nirvana. Let just one get away from you and you're in for a sad experience. Refer to the article by Dr. Ernesto Illy for details: http://tinyurl.com/complexity-of-coffee

Variable #1 Group Pressure: Conventional wisdom holds that group pressure should be adjusted to 9 bar. What CW doesn't address is whether this is dynamic (as the fluids are flowing through the puck) or static (with the fluids stalled at the puck - no flow) pressure. FYI: 9 bar dynamic pressure = 10 bar static pressure, and 9 bar = 131 psi.

Arbitrarily I've chosen it to mean 9 bar dynamic group pressure. To manage the pressure requires an adjustable OPV; present in all Classics, some Baby's, and other models. Those Gaggia models without an adjustable OPV can be modded by replacing the OEM water inlet with a Classic adjustable OPV (~$50). Then, with the aid of a portafilter mounted pressure gauge, the group pressure can be properly tuned.

Variable #2 Brew Temperature: Conventional wisdom holds that group temperature should be 196F to 203F. The Gaggia OEM brew tstat has a dead band of ~40F; meaning that at any given time the actual temp can be as much as 20F below or 20F above the optimum brew temps. To correct the problem requires one to temp surf (play with the steam tstat to manipulate the temperature) or mod the machine by adding a PID kit to replace
the brew tstat.

Personally, I've never been able to temp surf worth a damn. That's why I've championed the PID mod for Gaggia's. They're simple to install, kits range in price from $159 - $250, and make it dirt simple to hit a chosen brew temp. This is important, because in addition to the temps CW holds to be best, I've found
that each blend and single origin has its own temp sweet spot. A 1F difference in brew temp can make a huge difference in taste.

So, have you mastered the two machine variables yet?

Tex

[GC7]

YES

[peter]

Yes, same day it came out of the box.

[Tex]

BTW, I forgot to mention that you shouldn't rely on the gauges mounted on your machine to adjust the group or boiler pressure. I've worked on hundreds of machines and I've yet to find more than a handful with accurate gauges. If you take into consideration the bumps and shocks these get in shipment that's not too big a surprise.

If your retailer was worth a damn the machine should've been properly tuned before it got to you. But you'd be surprised how often this gets "overlooked"; mostly because the machines never come out of their factory crates before they get shipped. And often the machine was never in your retailer's possession, rather it was drop-shipped from the distributor. That's why it's always a good idea to tune your machine when you get it.

[peter]

So you might change the thread title to "Have You Tuned Your Machine Yet?" because you're saying the variables can't be mastered until you've checked the pressure yourself.

[Tex]

So you might change the thread title to "Have You Tuned Your Machine Yet?" because you're saying the variables can't be mastered until you've checked the pressure yourself.

Kinda sorta Peter - the pressure & temp need to be verified occasionally, so they really are variables. And the tuning is really the mastery of the machine.

And as others will tell you, that's just part of the equation of making quality espresso. But everything else is operator variables and I'll leave that for the experts to discuss.

[peter]

I may just snoop around S1Cafe forum, and see if there's a PF gauge floating around.

Apart from actually measuring it, there could be something said for adjusting pressure (and group temp for that matter) by taste.  Both are easy enough to do, for me at least.  Like you say conventional wisdom is 9bar, but even if we use a PF gauge that's spot-on, 9bar may not produce the best shots.

Taste should be the tutor in the mastering of the variables.

[YasBean]

My VBM DB Super came with pressure at 11.4 bar indicated and PIDed coffee boiler.  As they said indicated pressure is ~1 bar over grouphead pressure, I adjusted the OPV to 10 bar static.  After six months, I decided to readjust back to 11 bar indicated static, and have been much happier.  I can usually use grind and tamp to hit just about 10.6 bar indicated, and the taste is better.

As for temp, well, with a PID, I have to adjust every few days, depending on the bean.  Nothing is permanent!

[staylor]

Howdy Folks,
I don't care which espresso machine you have, or how much you paid for it, there are just two machine variables to manage.

Are you going to make this a quarterly thing?

You know it always goes off the rails.

[peter]

Howdy Folks,
I don't care which espresso machine you have, or how much you paid for it, there are just two machine variables to manage.

Are you going to make this a quarterly thing?

You know it always goes off the rails.

If only we could get Chris to write some code so you wouldn't see these, you of low resistance.   

Maybe we should derail the thread and discuss the merits of 'let taste be the tutor of mastering the variables.'

YasBean has a good post; he adjusts his machine based on taste and only keeps the setting if the taste improves.

[Tex]

Howdy Folks,
I don't care which espresso machine you have, or how much you paid for it, there are just two machine variables to manage.

Are you going to make this a quarterly thing?

You know it always goes off the rails.

Only when folks with their own agendas misquote me or take something out of context. When the post is read in its entirety there's nothing to argue about.

[Tex]

Howdy Folks,
I don't care which espresso machine you have, or how much you paid for it, there are just two machine variables to manage.

Are you going to make this a quarterly thing?

You know it always goes off the rails.

If only we could get Chris to write some code so you wouldn't see these, you of low resistance.   

Maybe we should derail the thread and discuss the merits of 'let taste be the tutor of mastering the variables.'

YasBean has a good post; he adjusts his machine based on taste and only keeps the setting if the taste improves.

Actually Peter, what I read was that he chose a higher group pressure (~11 bar static/10 bar dynamic) than CW advises and leaves it set at that, adjusting his grind and tamp to achieve ~10.6 bar.

What he does vary is the brew temp, the same thing I advise at the end of my post.

So YasBean has mastered the group pressure and temp variables, at least to his satisfaction.

[staylor]

Howdy Folks,
I don't care which espresso machine you have, or how much you paid for it, there are just two machine variables to manage.

Are you going to make this a quarterly thing?

You know it always goes off the rails.

Only when folks with their own agendas misquote me or take something out of context. When the post is read in its entirety there's nothing to argue about.

Choooo chooooooooooo...

[peter]

Maybe we should derail the thread and discuss the merits of 'let taste be the tutor of mastering the variables.'

YasBean has a good post; he adjusts his machine based on taste and only keeps the setting if the taste improves.

Actually Peter, what I read was that he chose a higher group pressure (~11 bar static/10 bar dynamic) than CW advises and leaves it set at that, adjusting his grind and tamp to achieve ~10.6 bar.

What he does vary is the brew temp, the same thing I advise at the end of my post.

So YasBean has mastered the group pressure and temp variables, at least to his satisfaction....

...as has anyone else who can consistently pull drinkable shots.  Taste is the tutor.

[Tex]

Howdy Folks,
I don't care which espresso machine you have, or how much you paid for it, there are just two machine variables to manage.

Are you going to make this a quarterly thing?

You know it always goes off the rails.

Only when folks with their own agendas misquote me or take something out of context. When the post is read in its entirety there's nothing to argue about.

Choooo chooooooooooo...

I don't mind a thread spinning into a pissing contest as long as I learn something from them. You've made me aware that my concentration on mastery of the machine is only part of the equation for making quality espresso. Technique is equally important, otherwise every Tom, Dick, & Harry could buy the latest Whiz Bang X3300 and begin whipping out great shots. That just doesn't happen!

And I accept that some baristas could take a Krups steam toy and turn out very drinkable shots coffee. But for the vast majority of home baristas, it's my contention that a properly tuned espresso machine is the best starting point for learning how to make quality espresso. In that context I point out to these folks what constitutes a properly tuned espresso machine, in my very experienced opinion.

Once the home barista has a well-tuned machine, the next order of business is to find someone who can teach the basics of making quality espresso. As a former educator who believes most people learn in incremental steps, I like to start the budding home barista off with a method that I know from experience will let them make very drinkable shots after a few attempts. Once the basics are learned, the now advanced home barista can move on the the finer aspects of pulling shots, armed with a comforting knowledge that the basics have been mastered.

For my money, that's about it - make sure the machine is capable of producing quality shots, that the barista has mastered the basics and knows how to build a good shot of espresso, and then pass them off to someone else with knowledge of how to produce great shots under varying conditions.