Feedback from E-61 flow control pressure gauge

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RecontraBacan
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#1: Post by RecontraBacan »

I gave my eminently reparable/rebuildable 2011 Alex Duetto II to a young dad I met through here last week outside the front door of Clive Coffee in Portland on Saturday afternoon. I then went in and picked up my new ECM Synchronika w/ flow control. OMG, am I having fun again! The ECM blind portafilter is on backorder, so can't wait to get that to get some additional visual feedback. But playing with the flow control preinfusion and ramp up and ramp down is a hoot. Leaping out of bed again in the morning, just like I did in 2011 when I first got my Duetto.

It occurs to me that the Flow Control pressure gauge is also a huge source of feedback. Pump pressure is 9 bars, and most of my shots go up to 8 bars with the paddle wide open on the group gauge. Of course if I choke a shot, the group gauge will be 9 bars (because no water is flowing--water velocity at the pump is the same as at the head: zero--and if I brew a gusher, the group pressure is going to be way low). I know there's so many variables, but here's my question:

Just as a starting point, if I got my pump pressure set at 9 bars, is there a presumptively "ideal" pressure I should see in the group head pressure gauge? I remember years ago learning the standard "ideal" starting point was about 18g. coffee per double basket, 9 bars of pressure, and a 27 second shot. Then weight (and really expensive scale manufacturers--just kidding) got involved to kind of trash that ideal. But just as a starting point, is there a generic "ideal" group pressure for a shot, kind of like the old 27 second shot standard. Obviously, if I do one shot at 8 bars in 27-30 seconds after preinfusion, and the next one is 7 bars in 20 seconds because of increased water velocity, I've probably got some channeling issues or a poor grind/tamp, and that's some feedback. But is there a place I should ideally be as a starting point to my experimentation?

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BaristaBoy E61
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#2: Post by BaristaBoy E61 »

I would be looking at the bottom of a naked portafilter through a shot mirror, live in the moment by what I see, kill the shot when the desired weight of extraction has been reached, use the shot timer as a guide for adjusting the grinder and judge by taste.

... And don't forget to have fun! That, you seem to have already mastered.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

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cannonfodder
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#3: Post by cannonfodder »

The brew pressure gauge can give you a wealth of information. It takes a little time to learn what it is telling you.

I will make minor adjustments to pressure as the shot progresses, primarily as the flow starts to increase which is noted as a slow decline in the pressure gauge. That signifies that a lot of the solids have been extracted and the flow is accelerating through the puck. I will feather down the pressure so say, 6 bar to maintain the flow rate to the end of the shot.

You also know it is not going to go well when you do a pre-infuse dwell at say 4 bar and you have drips in 5 seconds out the spout. You know it is going to be a gusher which people like to call a 'turbo' shot nowadays. We called them sink shots. You can run a lower pressure to try to salvage the shot.

You also get different flow rates with and without pre-infusing or slow pressure ramp at the start of the shot. A slower ramp tends to get you a faster flow versus jumping right up to full pressure. Assume that is attributed to the puck not getting compressed at the full 9-bar, less densely packed aggregate. Pressure/flow profiling can be entertaining.

Poor puch prep, you will see it in the gauge feedback, channeling, etc... You will start to feel for what is going on over time.
Dave Stephens

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Jeff
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#4: Post by Jeff »

My experience has been that there are many ways to pull a good shot, though the result will be different depending on how you choose to do so.

Around 8 bars in the basket for a classic roast, extracted with a 1:2 ratio over around 25 seconds is pretty typical for a classic espresso with a flat-profile, pump-driven machine.

Dave's comments on lowering the pressure to keep the flow from running away later in the shot is an approach that many find helpful across a range of roasts, ratios, and extraction times.

My experience with medium-roast coffees (lighter espresso blends, like George Howell's Alchemy or many American-style filter roasts) as espresso has been that a lower pressure tends to give me a flavor profile that I prefer. I tend to pull shots around 6 bars peak, tapering off as the shot progresses. This is probably similar to the pressures in a classic lever machine.

When I was exploring pressure on my flat-profile E61 HX, I found that making a relatively large change in pressure was needed to convince myself that there was a change in the cup. Based on that change and then going too far, I found a number on the dial that worked for that machine and the coffees I was pulling at the time.

My suggestion would be to stay simple and repeatable on your profiling and try several cups at a couple of different pressures, maybe 6 and 8 bars. It may take a week or more to come up with a preference. Taking good notes of your impressions helps me, as does tasting once the espresso is no longer hot. When hot, about all I can taste is, well, hot.

In working with a machine that has very repeatable and easily adjustable extraction pressure, I found that going much over 8 bar in the basket for the medium-roast coffees I was pulling resulted in some flavors that I didn't enjoy.

If you decide to explore even lighter roast coffees, you may want to consider even lower pressures. I tend to pull with a 5-6 bar peak with the European and Asian roasters' "filter" coffees as espresso.

RecontraBacan (original poster)
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#5: Post by RecontraBacan (original poster) »

Wow! Thank you for those replies and all that information. It definitely opens up the possibilities. Definitely have my work cut out for me for the next few months. Thanks again!

PIXIllate
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#6: Post by PIXIllate »

I've spent a significant amount of time working out a flow profile and the matching techniques required for using an e61 in a manner similar to the "blooming"/lever style shot described above. There is a video and description in this thread:

An Even MORE Considered Approach to E61 Flow Control (now with video)

Pressino
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#7: Post by Pressino »

One thing you need to understand is that most (but not all) of the e61 machines that are supplied with a flow control device have had the "standard" pre-infusion chamber spring replaced with a stiffer spring. ECM and Profitec machines supplied with their FCD's come with the new stiifer spring installed. The "standard" spring was designed open at about 3 to 4 bar to provide "automatic" pre-infusion when you flip the lever to make a shot. The replacement springs supplied with FCD's is stiffer and openbs at around 8 bar, essentially defeating the traditional e61 pre-infusion ramp up. Doing so, according to the designers of FCD's allows complete manual control of pre-infusion vis the FCD throttling valve.

Maybe, but I don't believe that's a great idea, so I replaced the stiff FCD-associated spring with the older less stiff spring. Contrary to the designers of FCD's, my experience has shown me I now have better control over extraction flow.

PIXIllate
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#8: Post by PIXIllate »

I completely agree that the original spring offers FAR more control when aiming for specific hold/bloom pressures as described in the thread I linked to above.

Pressino
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#9: Post by Pressino replying to PIXIllate »

Indeed, we've been discussing the relative advantages and disadvantages of the stock versus stiffer pre-infusion springs here on HB.com since 2019, prompted by the earlier arrival of the Bianca with its flow control device and subsequent availability of other e61 FCD's. Some even suggested removing the lower chamber spring and running e61's with the FCD alone...

PIXIllate
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#10: Post by PIXIllate »

What is the pressure ramp like with the spring removed entirely?