As I understand the "Fellini move", after having pulled the lever down part way (somewhere between a quarter and half), one returns the lever to the top and then proceeds to pull it down all the way in the normal fashion, the object being preinfusion. This may just reveal my ignorance, but I have 2 questions about this procedure: (1) Isn't preinfusion accomplished anyway if one just waits a bit to allow boiler pressure alone to extract several drops of espresso before beginning to push the lever down?
(2) Won't a Felliniesque upward pull suck up unwanted preinfused coffee and and fines past the shower screen into the cylinder, ultimately resulting in a bit of an oily mess and necessitating more frequent shower screen removals for cleanup?

You will hopefully get some advice on fine tuning the lever pulls to avoid disturbing the puck.....but this about preinfusion.
The ability for a machine to perform complete preinfusion, drips from the pf without any lever or pump power depends largely on the pressure behind the water....with a line feed machine this is line pressure, often adjusted through a reduction valve and on a boiler fed machine, such as the EP the pressure is totally dependent on the boiler pressure. Of course, as you increase pressure to get a good infusion before the pull you increase temperature as well, which is a harsh tradeoff with a La Pavoni. But since you are thinking physics here....at rest the group is full of water which has been heated by association with the boiler through the contact of metal on metal. When you lift the lever that water is forced back into the boiler and there is a slight rise in pressure....with an EP there is also a spurt of steam out the top valve to compensate....a machine with no active steam bleed on boil will simply contain this pressure jump. So with the lever up water is re entering the group but this time above the coffee instead of above the piston and the water will sit on the puck and slowly travel downward, advanced by the boiler pressure....inevitable movement but depending on your basket prep, possibly slow, therefore the coaxing since there is this idea of no more than 3 or so seconds of preinfusion (likely fallacious). You are right, complete preinfusion to visible drips can occur with the Pavoni by boiler pressure alone but you really have to fine tune your grind and tamp to let this happen since it will be occurring with a pressure likely less than 1 bar. I think that the result is, in general with a coarser grind and light tamp to get passive preinfusion, less crema than many people are shooting for, not to say a bad tasting cup, possibly an excellent cup but the overall consensus from what I can tell is that for good crema on a Pavoni one needs fine grinds. When we have used an EP we get passive infusion to drips with no Fellini but we grind coarser and do not tamp to get this effect.

I've been going back & forth on this well (see my other Pre-Infusion, longer vs. shorter? thread)....
The #1 thing that confuses me currently is the relationship between pre-infusion/ Felllini move & grind.

With a shortest possible pre-infusion and no fellini, i can set my grind finer without "choking up" the machine. But by doing this I suspect I am not saturating the puck completely. With a slightly longer pre-infusion (:06-:08) and a 1-2 short fellini moves at the top %20 of the lever stroke, I get better pre-infusion, but the machine feels choked for the first 1/4 of the pull. Once the espresso is flowing though, it flows nicely.

Currently my take on is that the fellini move is beneficial when used as part of the pre-infusion phase, to help with saturating the puck. Once the espresso is flowing, no more fellini. As for damaging the puck, I just make sure to pull up very slowly, and only at the top 1/4 of the stroke. That seems to be working better for me, based on taste, crema and color.

F.M. wrote:The #1 thing that confuses me currently is the relationship between pre-infusion/ Felllini move & grind.

With a shortest possible pre-infusion and no fellini, i can set my grind finer without "choking up" the machine. But by doing this I suspect I am not saturating the puck completely. With a slightly longer pre-infusion (:06-:08) and a 1-2 short fellini moves at the top %20 of the lever stroke, I get better pre-infusion, but the machine feels choked for the first 1/4 of the pull. Once the espresso is flowing though, it flows nicely.

Preinfusion saturates the coffee, which swells. Hydrostatic pressure has great force. Illy describes how the ancient Romans quarried stone by pouring water over a dry wooden peg which had been hammered into a hole drilled in the stone. When the peg absorbed water, it would swell, and the slab would split off.

Very fine grind and heavy tamp can cause over-compaction, but the relationship you need to be concerned with, IMO, is that between preinfusion and dose. If there's insufficient room in the basket (because of overdosing) for the coffee to swell, it becomes overly compacted, and the extraction gets "choked". So you need to lower your dose a bit when that happens. Or ease off on the lever. Too much brew pressure can contribute to the over-compaction. Or a little bit of both.

Note that this choking can occur during the infusion as well as during the preinfusion. If you do not preinfuse, but begin to pull the shot, the coffee can swell during the infusion and the extraction can choke midway.

So, my maxims would be: at first, dose moderately, tamp moderately (or very very lightly), grind not too fine, and preinfuse for a few seconds under boiler pressure or with a very shallow Fellini. You can always decide to become immoderate with any variable(s) after you have all-things-in-moderation working for you.

Summary:
Causes of over-compaction and "choked" extractions, individually or in combination:

1) too much coffee in the basket
2) too fine a grind w/ too heavy a tamp
3) too much brew pressure

Good stuff, thanks for the info.
I think I need to revisit dosing a bit less. I tried using the edge of my rocky grinder's lid to level down a bit, but didn't like the results. Maybe I will try a spoon or something with a smoother radius, or using the single basket as a measuring device.

The idea of using a scale to weight beans ground for each pull... that's just a little too much hassle for me.

F.M. wrote:Currently my take on is that the fellini move is beneficial when used as part of the pre-infusion phase, to help with saturating the puck. Once the espresso is flowing, no more fellini. As for damaging the puck, I just make sure to pull up very slowly, and only at the top 1/4 of the stroke. That seems to be working better for me, based on taste, crema and color.

If I understand you correctly, you're saying that pulling up very slowly and only at the top of a 1/4 of the storke will prevent pre-infused coffee from being sucked up behind the shower screen? I may be wrong, but it would seem to me that pulling the lever back up is going to result in suction force, whether it's done slowly or quickly . . . I'm not talking here about any violent moves which would "disturb the puck", but rather just about the suction environment created by the upward pull, which would displace the liquid portion of the pre-infused puck

In my experience, Alan, something always manages to make its way behind the screen, but the Fellini move does increase this as you suspect - more so on some machines than others.

I think there can be various reasons for opting to Fellini. Depending on the machine this may be to increase shot volume, to increase preinfusion saturation and so on. Whether it's desirable in my opinion depends on the beans as well as on the machine.

I don't think there's a golden rule on this one: personal preference comes into it, too. Many of the testers on the lever machine shootout preferred a very short/no preinfusion.

I sometime use the Fellini for a double basket ristretto, for example, or on the Caravel, but not on the Cremina and MCaL.

Cheers

Mike

AlanD wrote:If I understand you correctly, you're saying that pulling up very slowly and only at the top of a 1/4 of the storke will prevent pre-infused coffee from being sucked up behind the shower screen? I may be wrong, but it would seem to me that pulling the lever back up is going to result in suction force, whether it's done slowly or quickly . . . I'm not talking here about any violent moves which would "disturb the puck", but rather just about the suction environment created by the upward pull, which would displace the liquid portion of the pre-infused puck

It's goopy, not a lattice.

AlanD wrote:it would seem to me that pulling the lever back up is going to result in suction force, whether it's done slowly or quickly . . . I'm not talking here about any violent moves which would "disturb the puck", but rather just about the suction environment created by the upward pull, which would displace the liquid portion of the pre-infused puck

Hmmm. reminds me of a demo I got from a door-to-door vacuum saleperson! They were keen to demonstrate that a "vaccum" does nothing of the sort.

Well anyways- I've been experimenting with dosing down a bit, using the Vivace Vita roast and the single basket as a measuring device. I have to say it hasn't been the magic bullit I had hoped for....
First I tried dosing less, but same grind and packing pressure (20# now?) and short pre-infusion (:03) OK results but no real improvement and not great crema
Then I tried 1/2 step finer grind, again dosing less and same packing pressure, with a :10 second pre-infusion, this choked the machine a bit, but things were easy to get moving once I pushed through the initial resistance. Less crema, possibly over-extracted? Crema had that "cracked surface" appearance.

One thing that bothers me about dosing less, is there's no way to level the grounds before packing.

I'm thinking next I try a coarser grind & full dose? I may be over-extracting regardless of dose, due to grind.

F.M. wrote:Hmmm. reminds me of a demo I got from a door-to-door vacuum saleperson! They were keen to demonstrate that a "vacuum" does nothing of the sort.

Maybe I'm just not sharp enough this evening, but are you trying to say that there is no suction action on an upward pull?

timo888 wrote:It's goopy, not a lattice.

Forgive me timo888, but I have even less idea what you're talking about. Can you elaborate?