What an ingenious and yet simple set up this whole preinfusion thing, but it is easy to counter the whole preinfusion process with a microswitch mounted at an incorrect depth.

The micro switch is simple to adjust so that it sticks out of the machine body only enough to activate the pump ONLY when the E-61 brew lever is raised all the way up. The pump isn't supposed to activate before, or at the same time that the valve inside the brew group opens to allow water to pre-infuse the grounds (the valve which HB referred to in a previous post). If it does, then you no longer have pre-infusion...it was adjusted out of your machine that was designed for preinfusion by incorrect microswitch depth/placement.

So the only way to make sure this doesn't happen is to adjust the switch depth/placement correctly. Too bad our machines don't all come situated correctly to allow the pre-infusion to occur. Mine wasn't set up correctly either, but Chris Coffee has been incredible in their customer support, and they are sending me a new microswitch with an included spacer to insure that the switch will be positioned to activate the pump only after pre-infusion has occurred. (at no charge) I feel like tipping them.

By the way, I know some astute observer on this site will see my static pressure is too high. Well I have it regulated now down to 4 BAR from the 6 in the photo below. Thanks HB for the great info on the regulator valve, etc. My brewing BAR is now right at 9.5 give or take a smidge, vs the nearly 10 it was previously. I didn't have to adjust the rotary pump...I just installed the regulator and adjusted it. No fluctuation, no jumpin around. The gauge sits still even if I turn the kitchen faucet on and off like a man with a post hole digger. Know what I mean?


And yes, I took the sticker off the brew head. We don't need no steenkeen steekers to know it's hotter than a pistol.

Rich

olypdd wrote:What an ingenious and yet simple set up this whole preinfusion thing, but it is easy to counter the whole preinfusion process with a microswitch mounted at an incorrect depth.

Um, on the E61, the gradual pressure ramp up, over ca 10 seconds, **after** the pump is activated, is called the preinfusion. A springloaded cylinder inside the manuial group, or a filling cavity in the solenoid versions, takes care of this process.

The "pre-pre-infuse" of opening the valve without starting the pump has no merit in pourover machines, since any puck soaking requires line pressure of at least 1.5, and probably more like 2.5 bar. In plumbed machines, most people trying back to back shots once using it, once not, have noticed no difference; although the procedure has, like everything else in espresso, some advocates.

another Jim,

I enjoy this dialogue because it provides me with further insights to consider, and this is one of the main reasons I have joined this site.

You make an interesting point, but in the case of my machine, as soon as I engage the pump, the water is pumping out at what would appear to be enough pressure to hit the puck with a fair amount of force, vs a mere preinfusion (passive release of static line pressure). When there is a loaded portafilter in the machine, it does ramp up to brew bar in a matter of seconds. When I raise the brew activation lever with the machine off, water runs out the brew group at a leisurely trickle, that which would appear to saturate the grounds in a manner consistent with the idea of preinfusing them in a way so as to not disrupt the integrity of the tamp, and to counter the ability for water at brew pressure to channel along side the puck, vs saturating it uniformly.

I am new to the E 61 thang, however, I did have a Zaffiro some time back, and also, have read the forums here, and at CG extensively as well as elsewhere. I must have missed something, and appreciate your insight. However, I believe that better pre-infusion will occur with the non "live", or passive release of static pressure first, then transitioning through the brief ramp up to pressure, than the active pump pressure, (even if it initially isn't up to full brewing bar), hitting the puck. In the case of my machine, it is plumbed in, on a regulator, and static pressure at the machine is 4 BAR.

I find that when I lift the handle partway, that a valve is opened and the static pressure released allowing water to run out as I mentioned above. It is occurring manually, and potentially before the pump is activated if the switch isn't sticking out too far. This is not to say that something else isn't being activated, as you have mentioned, when the pump is turned on.

What I have noticed recently is that when I manually preinfuse the puck for a second (or so) before I turn the machine back on and activate the pump, the shot shows much more even extraction.

Perhaps I misunderstood what exactly "defines" preinfusion as it relates to the operation of an E-61 brew group, but based on what I have read, and derived from speaking to Chris Coffee, it seems reasonable that initial soaking of the grounds at just over static pressure vs live pump pressure provides less invasive pre-infusion.

I also noticed that when using the bottomless portafilter on my Venus (vibe pump, no pre-infusion, non E-61), that I had alot of channeling. Wouldn't the same ramp up to pressure there serve to preinfuse the coffee as you mentioned with the E-61. In fact, it seems to ramp up more slowly than my Vetrano rotary pump, but I haven't timed the two. Perhaps I will do this.

Also, I have read the posts regarding "leveling of the coffee" vs tamping to insure even extraction. Interesting stuff for sure, but I haven't played with the idea as of yet.

Thanks for the info. Interesting stuff.

Rich

olypdd wrote:You make an interesting point, but in the case of my machine, as soon as I engage the pump, the water is pumping out at what would appear to be enough pressure to hit the puck with a fair amount of force, vs a mere preinfusion (passive release of static line pressure). When there is a loaded portafilter in the machine, it does ramp up to brew bar in a matter of seconds. When I raise the brew activation lever with the machine off, water runs out the brew group at a leisurely trickle, that which would appear to saturate the grounds in a manner consistent with the idea of preinfusing them in a way so as to not disrupt the integrity of the tamp, and to counter the ability for water at brew pressure to channel along side the puck, vs saturating it uniformly.

I did a little experimentation as documented in The Secret Life of Ristrettos, excerpted below:

HB wrote:While my comment isn't directly related to this thread, lately I've been experimenting with extraction rates as part of the Vetrano wrapup. That, plus Ken and Jim's The Impact of Preinfusion on the Taste of Espresso Shots has me thinking about extended preinfusion for E61s, despite their native capability.

Combining the two ideas, I increased the water inlet pressure to three bar. When the lever is up and the machine is off, water flows readily through the grouphead. The "rebound" time for the Vetrano is 30 seconds after the flush, so I reserved the last 10 seconds for additional preinfusion. Specifically:

• Flush as usual; start preparing the portafilter (or prepare basket separately and drop it in later)
• Lock in the portafilter
• The heating element will click off 15-20 seconds after the flush; once it does, turn off the machine
• At the 20 second mark, lift the lever up. The mains pressure will preinfuse the puck ever-so-gently
• After 30 seconds, turn on the machine. Since the lever is still up, the pump begins immediately.

So what does this have to do with ristrettos? Getting the grind perfect for ristrettos on heat exchanger espresso machines can be tricky. Too slow a flow and the HX will overheat, producing a doubly-bitter shot (partially from high temperature, partially from overextraction). Too fast a flow and the rich, sweet, punchiness of a ristretto can be lost. The extra preinfusion appears to increase the margin of error.

As a rule of thumb, ten seconds of (extra) preinfusion equals a grinder adjustment of two millimeters coarser on the Mazzer Mini, or a reduction of coffee equal to approximately 1.5 grams (*). Running the mega-sized preinfusion "softens" the puck and opens a wider window for good extractions. My results so far for ristrettos are improved, though the opposite occurred for regular doubles, where the flavors became muddy and flatter.

(*) Don't take these numbers too literally, they are meant to convey that the effect is very small.

The machine off-on trick avoided any quibbling about the "3/4" position being used for preinfusion. I'm not convinced of the merits of this approach, but it's worth further experimentation.

olypdd wrote:Wouldn't the same ramp up to pressure there serve to preinfuse the coffee as you mentioned with the E-61. In fact, it seems to ramp up more slowly than my Vetrano rotary pump, but I haven't timed the two. Perhaps I will do this.

It's not easy to compare different grouphead designs; adding different pumps makes it even more challenging. That was a surprising lesson I learned in Pressure profiles, preinfusion and the forgiveness factor, i.e., the assumption that a slow pressure ramp up = preinfusion = high forgiveness factor isn't true. I thought it didn't make sense, but several others (including Jim) have confirmed my findings that the A3, which ramps up as fast as a rocket, is a forgiving espresso machine.

HB,

Very interesting info. I also looked over Ken and Jim's research. One thing I will say about that....I don't think I could discern any difference in shot quality between the rotary and vibe pumps, nor did I expect to. I enjoy the rotary and direct connect for all the obvious reasons, and acquired both with the belief that neither would diminish shot quality.

As for preinfusion time, it has been my impression that it was designed to be a very brief event on the way to live brew pressure's introduction to the puck. After all, moving the lever upwards to brew takes very little time indeed. So in my mind, it was interesting that such a "brief" event along the way, could have such impact on shot quality. Not flavor necessarily, but rather extraction.

I am dazzled at Ken and Jim's research. I would have never devoted so much time and focus to this as they have. A part of me is inclined to fly by the seat of my pants, utilizing intuition and instinct along the way, and making it more of an art (within reason). It's also important to have some hard data to rely on as a basis for what we do to reach our goal of quality espresso. Hey, I want to try Eric's design in monitoring brew water temp and see how that may benefit my consistency of shot quality. So thanks to Ken and Jim for the trouble. I will just soak it up and enjoy the benefit of all this.

HB, when you wrote of forgiveness factor and its correlation to ramp up speed, it reminded me of that which I wrote of above...the fact that any passive introduction of water to the puck just before the pump kicks on, is a situation where preinfusion is very short, and hardly a pause. Very interesting findings you have shared.

HB...thanks for the info. I intend to try the technique you listed. I love Ristrettos and it will be interesting to see how things turn out.


Rich

olypdd wrote:What I have noticed recently is that when I manually preinfuse the puck for a second (or so) before I turn the machine back on and activate the pump, the shot shows much more even extraction.

Perhaps I misunderstood what exactly "defines" preinfusion as it relates to the operation of an E-61 brew group, but based on what I have read, and derived from speaking to Chris Coffee, it seems reasonable that initial soaking of the grounds at just over static pressure vs live pump pressure provides less invasive pre-infusion.

I also noticed that when using the bottomless portafilter on my Venus (vibe pump, no pre-infusion, non E-61), that I had alot of channeling. Wouldn't the same ramp up to pressure there serve to preinfuse the coffee as you mentioned with the E-61. In fact, it seems to ramp up more slowly than my Vetrano rotary pump, but I haven't timed the two. Perhaps I will do this.

Also, I have read the posts regarding "leveling of the coffee" vs tamping to insure even extraction. Interesting stuff for sure, but I haven't played with the idea as of yet.

Hi Rich. I humbly suggest you reread those posts, take the lessons learned to heart, and work on your barista skills. Yes, prewetting may provide a more even extraction because it allows the coffee grounds to expand and fill in cracks in the puck. But you'd be better off fixing the grind/dose/distribution/tamp defects that produced those imperfections in the first place, and only then play around with pre-preinfusion. Note that Dan used an extended preinfusion for reasons of taste, not to fix channeling.

No offense intended. We all go through this with the bottomless PF. It's a great tool for improving espresso technique - and teaching humility.
________
John

John,

I agree with you....I think I might clarify a couple of things. When I read some posted questions and discussions on this site regarding micro switch placement and preinfusion, it seemed that the point wasn't clearly made that the switch could be adjusted to allow for a quick and gentle prewetting of the puck before the pump kicks on (except, of course that HB posted the drawings of the groups guts and made things more vividly clear). It was always my understanding that this was how the E-61 was supposed to be set up, and vendors who sell these have contributed to this understanding, and that it was designed in this way to help prevent channeling. Perhaps it wasn't the intent of the design, so then I ask, since it is something this group can do, does it contribute to better shots?

Also, I have read the discussions, and observed the renderings of the E-61 group on this site and others to gain an understanding of its design, and how water moves through it.

What I have also understood, was that pre-infusion contributed to flavor, and that one could play with this whole process and possibly experience different flavor profiles. HB apparently studied this, and reported his findings regarding ristrettos, which I found very interesting. In the photos below, the one on the left is a standard M1A1 double, and those on the right are ristrettos with a wee bit of preinfusion. Now differences in light and photo techniques aside, you can still see a difference in "color". The ristrettos were sweeter and more flavorful, and the one on the left was pretty good, and smooth, but no real complexity in the flavor profile.

I focused on channeling, because with the naked portafilter, it's one of the main things you hope you won't see during extraction, however, I was seeing channeling at times, and could not determine if it was just because of tamp/techniques, or a lack of preinfusion, or what. Channeling was something that seemed to become less of a factor when I did a little extra preinfusion. BUT, I have said from the start, that tamping with a naked portafilter was awkward to me, as it doesn't sit nice and level like my LaMarzocco, etc. Reading the threads here has led me to try tamping with the basket removed. I am seeing what appears to be improved results in extraction. It too is a bit awkward, but only because it is new to me, and not physically like trying to hold a naked unit on the edge of the counter on a towel.

Plus, I have been incorporating BobYs technique for flush, wait 3 mins, flush 2 oz, and wait however many seconds gets you the brew temp you're after. I am impressed thus far.

My machine is "new" to me, so I, like anyone else, am getting acquainted, and applying new techniques at the same time. I have no trouble with being humble. I have learned that it is best to approach things in life with an attitude of humility and discernment. I am trying to learn and improve...bottom line. I will say that with my Elektra and Venus, I had grown to the point that pulling most incredible ristrettos was a consistent easy effort, and that with no emphasis on any attempts at preinfusion. (although it may have been occurring in some manner) It only became a real interest to me when I purchased an E-61 machine, because preinfusion was always represented to me as an important design feature of the E-61. Not to compensate for poor technique, but to compliment proper technique.

I have using BobY's heat management regimen on my Vetrano since yesterday and I am getting close. The body, color and crema of my ristrettos overall is beautiful, but I can tell by "taste" that the brew temp is very slightly high. Or perhaps it's because I didn't try the manual infusion on these last 3 pulls. <gasp, that infusion word again> The cool thing about BobY's method is that the taste will clue me in on how long to wait after the 2 oz flush.

On that note, one question I have is regarding the initial 6 oz flush. BobY has his machine set to 1.1 BAR boiler pressure. I have a Vetrano with a boiler pressure at 1.2 BAR. Should I flush more than 6 oz initially when the machine has been idle a while? Say more like 7-8 oz? OR perhaps wait less than 3 minutes to do the 2 oz thang? I will have to cogitate on this a spell.

I also threw another artifact into the whole mix....a triple LaMarzocco basket. I like tamping into this one out of the portafilter, as it taller and easier for my big hands to deal with. The consistency of even extractions is improving very quickly. I believe it was anotherJim who mentioned some time back that tamping in the same type of motion as a coin going round and round before it falls flat is an interesting idea to seal around the puck, and one I am trying as well. Stirring with the end of a large paperclip before tamping really mixes up the grind promoting more uniformity throughout the puck, and makes me wonder why the heck I didn't try this before.

I don't believe I would be pulling great shots so soon on my HX if it weren't for the great input of HB members. I look forward to pulling outstanding shots once I have settled into my routine.

Thanks again for the great insights and critique.

Rich

olypdd wrote:I have a Vetrano with a boiler pressure at 1.2 BAR. Should I flush more than 6 oz initially when the machine has been idle a while? Say more like 7-8 oz? OR perhaps wait less than 3 minutes to do the 2 oz thang? I will have to cogitate on this a spell.

For the Vetrano, I would leave the flush amount the same and reduce the rebound time by 5 seconds if the espresso taste indicated the brew temperature was too high. BobY's keep it simple instructions are consistent with flush-rebound-pull, not flush-n-go, and I obtained better results that way. Most of the semi-commercial HX espresso machines perform better using one or the other, while some will only perform correctly with one approach (for example, the Elektra A3's recovery was too fast for anything but flush-n-go, i.e., it's "rebound" maximum was around 10-15 seconds).

Thanks Dan, that's in fact what I just tried (smoothed out the taste ) and will continue for awhile and see what the shot average is. Like I said, I'm close, and I prefer the Keep It Simple methodology. I'm too busy to do much else.

Rich