Pre-infusion with gravity-fed levers?

[Staffan]

I'm struggling with really nasty and soggy pucks with my Gaggia Achille. I'm getting pretty much crema, but it turns blond already after a few seconds. I got my dosing, distribution and tamping quite straight, and my grinder is a Rocky, so i don't think that's my problem.

However, i've been fooling around with pull techniques , trying to hit my puck more gently. It's quite difficult to know when i'm doing things right though...i'm pulling the lever gently, then smoothly increasing to full pressure when i believe that the puck have been soaked. However, my problem is that i have no idea of when the water first hits the puck!
I've been doing slow pulls to different positions and removing the PF to check if my puck is wet or not...However, judging from these tests, it seams like my pucks gets soggy and muddy as early as during the pre-infusion!

Does a pressure fall (like waiting for the pressure to drop and removing the PF) after a gentle pre-infusion destroy the puck? (i imagine it could). Do i need to pre-infuse at some pressure to keep the puck compact or something?

[peacecup]

Somewhere in these incoherent ramblings is a thread on the Fellini pull (a quick pump after the inital opening of the group). Since I began using this technique my pucks are always dry, and never damaged. I suspect the quick pump puts pressure on the puck during pre-infusion.

PC

[timo888]

Remove the portafilter and examine the volume and intensity of the water that comes through the screen in relation to the position of the lever.
Regards
Timo

[happytamper]

I have also had an issue with soggy pucks with my La Peppina. I have been using it for about a month and have tried all kinds of variations. I think it is a built in difficulty with this machine, perhaps it happens like this.

I pull down the lever and try to pre-infuse the puck. When I let go the lever goes up quite a bit and I pull it down again to get enough water into the group. I think that with this second pull a slight vacuum somehow loosens the puck at the same time as it brings more water. In a pressure machine this would not happen.

However this aspect of the La peppina is not necessarily a defect. I find the espresso made lighter in body but still full in taste and there is still a good crema.

[Dr Jim]

Since I may have inadvertently caused some confusion by posting the 'Fellini Move' topic, perhaps I should try to clear things up a bit...

My original posts were all directed towards spring-lever machines like the Elektra, the Ponte Veccio, big Gaggias, and my Conti. Please remember that these machines all work by the operator lowering the lever down, which raises the piston, compresses a spring, and uncovers ports through which hot water at boiler pressure (typically 1.2 - 1.5 Bar, or 18-24 PSI) can then flow and pre-infuse the puck.

Commercial spring-lever machines often have a pre-infusion detent which holds the lever down at the bottom of its stroke until the operator manually lifts the lever up to begin the shot. Traditionally, the lever was left lowered until the first few drops of liquid appeared at the portafilter spouts - these drops were allowed to fall into the drip tray, then the lever was gently raised with one hand while the other positioned the cup(s) under the spout.

The 'Fellini Move' simply adds a 3-5 second post-infusion phase where the lever is brought off the pre-infusion detent, pressure is briefly applied to the puck, the lever is returned to the pre-infusion detent for several seconds, and then gently lifted off the detent and the shot pulled normally.

Direct-action lever machines like the Pavoni, the Olympia, and the Gaggia Achille all work in an opposite fashion, in that the operator raises the lever to expose ports which allow water under boiler pressure to flow onto the puck - the Achille may operate at reduced pressure since it claims to use an HX loop fed by its own water reservoir - but in all cases, low-pressure hot water fills the chamber and floods across the top of the puck.

If the direct-lever operator wanted to achieve a pressure profile similar to a spring-lever machine's, I imagine that raising the lever, holding up at the top of its stroke for 3-5 seconds to ensure that the puck was flooded, the chamber full, and any steam bubbles purged would be the first step. Then I would further imagine that one would gently lower the lever until resistance was felt, continuing until you reached roughly 3-4 pounds of downforce on the lever, at which point you would attempt to hold this pressure until the first drops appeared or about 20 seconds, before applying the full 30-40 pounds of downforce needed to complete a shot.

I'm not sure that there's any advantage to be gained by attempting to duplicate the 'Fellini Move' on a direct-action lever, but if you are determined, I would guess that the closest approximation would be to press down with full force for 1-2 seconds, release back to 3-4 pounds on the lever for 3-5 seconds, then resume the full-force extraction. I don't see anything good happening by raising the lever at this point, and do see a potential for a number of Bad Things like fracturing the puck or introducing steam bubbles if the lever is raised.

Open-boiler machines like the Peppina or the Mini-Gaggia operate at atmospheric pressure and hence do not have a pre-infusion phase unless the operator chooses to invoke one by manipulating the lever - in which case the techniques will vary not only between manufacturers, but often from machine to machine depending upon age and condition.

However, the point which I started out to make - a very long time ago, sorry - is that I don't believe that pre-infusion tactics have anything to do with soupy, wet pucks - which I always attribute to defects in my tamp/grind/distribution techniques, which I immediately attempt to analyze and adjust. A process which I find fairly frustrating, and my neighbors - who get to watch a middle aged man in bathrobe and slippers swear blue oaths over some coffee grounds - find somewhat 'disturbing.'

Cheers

Jim

[timo888]

I have also had an issue with soggy pucks with my La Peppina. I have been using it for about a month and have tried all kinds of variations. I think it is a built in difficulty with this machine, perhaps it happens like this.

I pull down the lever and try to pre-infuse the puck. When I let go the lever goes up quite a bit and I pull it down again to get enough water into the group. I think that with this second pull a slight vacuum somehow loosens the puck at the same time as it brings more water. In a pressure machine this would not happen.

However this aspect of the La peppina is not necessarily a defect. I find the espresso made lighter in body but still full in taste and there is still a good crema.

Mitch, if this is how you're doing it, you're not going to get much of a preinfusion. Pullling down the lever on the Peppina won't send enough water to the puck, for only a dribble reaches the puck when the lever is pulled down -- by design. When the piston retreats, most of the water stays at the top of the piston chamber. So, pull the lever down all the way and then with your hand still on the lever allow it to rise gently about two-thirds of the way. This will cause the piston to advance and push some water, under a little bit of pressure, to the puck. Watch for the drips from the PF spouts. When you see the drips, push the lever down again and hold it down for 10-20 seconds to allow the water to soak the puck (and to fetch more water from the kettle into the piston chamber). Now let the lever rise under its own power.

Taking your approach you are simply sending several drips and then two slugs of water in succession through the puck. The puck won't have become saturated and it won't have expanded. The puck will lack definition.
Regards
Timo

[happytamper]

Timo,

That is worth a try. I will keep you posted.

[Staffan]

Since I may have inadvertently caused some confusion...

Good points. I just can't seam to find any errors in my grinding, distribution and tamping (i've attempted to fix my problems with the WDT as well).


About pre-infusion on the Achille - i don't believe the water is fed into the piston by gravity nor boiler pressure, but instead with suction from pulling the lever.
The cylinder seams to be split in two compartments by the piston - an upper and a lower. When pulling the lever, the lower chamber is compressed and the water is forced through the puck, while the upper expands and sucks water from the tank. When raising the lever, the water is sucked from the upper half to the lower through a one-way valve. Removing the PF and simply keeping the lever raised won't make any water exit through the shower head.

[hbuchtel]

About pre-infusion on the Achille - i don't believe the water is fed into the piston by gravity nor boiler pressure, but instead with suction from pulling the lever.
The cylinder seams to be split in two compartments by the piston - an upper and a lower. When pulling the lever, the lower chamber is compressed and the water is forced through the puck, while the upper expands and sucks water from the tank. When raising the lever, the water is sucked from the upper half to the lower through a one-way valve. Removing the PF and simply keeping the lever raised won't make any water exit through the shower head.

Ah, that makes sense!

But perhaps there are two one-way valves (one in the piston, one between the piston-chamber and water reservoir), otherwise raising the lever would draw quite a bit of air in through the puck. If there was a one-way valve that prevented water from flowing back to the water tank, then raising the lever would force water through the piston.

It appears to be part 93 on the parts list

PDF

(one-way valves (#45) also seem to control the flow of boiler water around the piston-cylinder)

If this is the case then you should be able to raise and lower the lever without fear of drawing air through a wet puck . . .

When you lock in the PF, how close is the coffee puck to the dispersion screen?

Henry

[timo888]

Timo,

That is worth a try. I will keep you posted.

Mitch,
Not only is it worth a try....it works. I've been doing it for a few weeks
Regards
Timo

[timo888]

Removing the PF and simply keeping the lever raised won't make any water exit through the shower head.

But don't just keep the lever raised. With the PF removed, raise the lever, slowly, from its lowest position to its highest, observing the volume and intensity of the water along the way.

Are you saying that NO WATER emerges from the shower screen until you press down on the lever?

Regards
Timo

[timo888]

But perhaps there are two one-way valves (one in the piston, one between the piston-chamber and water reservoir), otherwise raising the lever would draw quite a bit of air in through the puck. If there was a one-way valve that prevented water from flowing back to the water tank, then raising the lever would force water through the piston.

It appears to be part 93 on the parts list

PDF

(one-way valves (#45) also seem to control the flow of boiler water around the piston-cylinder)

If this is the case then you should be able to raise and lower the lever without fear of drawing air through a wet puck . . .

When you lock in the PF, how close is the coffee puck to the dispersion screen?

Henry, I see the valves #21 and #93 and #45 on the diagram.

If water for brewing flows by gravity down from the tank (#2) through valve (#21) out tube (#20) through one-way bush (#93) into the piston chamber, where is the water heated? Is the tube (#20) inside the boiler and surrounded by steam?

What is flowing through #45, and in which direction does it flow, and where does it go after exiting #45?


Regards
Timo

[hbuchtel]

Henry, I see the valves #21 and #93 and #45 on the diagram.

What is flowing through #45, and in which direction does it flow, and where it go after exiting #45?

Very hot water from the boiler is flowing through the #45s (which are facing in opposite directions).

(begin guesswork)

I think that inside the boiler is a tube that reaches from the higher of the two holes in the boiler (where the #57 washers attach) to the bottom (similar in appearance to the brew-water tube in steam-pressure levers.)

The slightly lower tube would end right in the wall of the boiler. The end of this tube is above the level of water in the boiler.

This way the water at the bottom of the boiler would rise up the tube and fill the oversized (hollow) group head and, after cooling, flow back into the boiler (like the thermosyphon effect of a E61 group head).

As I write this I feel some doubt creeping up about the assumptions I've made . . . I should note that 1. There is no evidence of this extra tube in the diagram, 2. There would be no need for the two one-way valves (#45), and 3. On the group head end I have no idea to what the two 'thermosyphon' tubes would attach (#s 46, 47) if anything.

If water for brewing flows by gravity down from the tank (#2) through valve #21 out tube (#20) through one-way bush (#93) into the piston chamber, where is the water heated? Is the tube (#20) inside the boiler and surrounded by steam?

So if the Group head (isolated from the piston-chamber and tube to tank) is filled with circulating (very) hot water, both the tube (#20) and piston-cylinder (#17) would act as heat-exchangers.

Any idea what that extention at the bottom of the piston-cylinder is for? (where the number 17's line is pointing at)

Henry

[mogogear]

But don't just keep the lever raised. With the PF removed, raise the lever, slowly, from its lowest position to its highest, observing the volume and intensity of the water along the way.

Regards
Timo

In case the higher profile folks at H-B are tooooo busy maybe they could request one of these " not-understood" machines and H-B could do a great test evaluation of one???? Lock up three or four of us at a nice resort for a week or so to put one through its paces?? A nice place like Thailand, Tim and Henry and I could hang out, drink espresso , surf, eat seafood and try to remember to do a write up....?

[timo888]

Does a pressure fall (like waiting for the pressure to drop and removing the PF) after a gentle pre-infusion destroy the puck? (i imagine it could). Do i need to pre-infuse at some pressure to keep the puck compact or something?

Without knowing how much water hits your puck, and when, and under what pressure, if any, it would be hard to say what's going on. You never answered the question about what you observe with the PF removed: where is the lever when the water starts to flow? Does moving the lever further cause the flow to increase in force/volume-over-time? Or does the flow remain constant?

Let's assume (without knowing yet for sure) that the water hitting your puck comes from the tank under gravitational force only (i.e. not under pressure) and that the rate of flow does NOT increase the higher you raise the lever. Open is open. (With my Cremina the water goes from a goodly flow to a rather vehement flow as the lever is raised to its full height.)

Water under gravitational force only will begin to soak into the puck at a rate which depends on the density of the puck, i.e. on grind and tamp. The denser the puck, the slower the rate of penetration. It might LOOK like the puck is soggy but the water might not have penetrated deeply into the puck. It could be sitting mostly on top of the puck. You will know that the bottom of the puck is wet when you see a drop or two coming from the spout.

To increase the rate of water penetration, you might need to PUSH some of the water GENTLY into the puck (i.e. at a pressure about 25-50% of brewing pressure). When you see a drop or two you can stop pushing and begin counting.

Now, if you're pulling a double you can decide when to fetch the second draught of water... before you express the first draught or after you express the first draught. That is, when you have pushed some of the water through the puck, there's room in the cylinder for more water and you can fetch it then and there. Or you can push that first draught of water completely through the puck and then go back for more water. It's your call.

Regards
Timo

[hbuchtel]

In case the higher profile folks at H-B are tooooo busy maybe they could request one of these " not-understood" machines and H-B could do a great test evaluation of one???? Lock up three or four of us at a nice resort for a week or so to put one through its paces?? A nice place like Thailand, Tim and Henry and I could hang out, drink espresso , surf, eat seafood and try to remember to do a write up....?

Henry

[timo888]

A nice place like Thailand, Tim and Henry and I could hang out, drink espresso , surf, eat seafood and try to remember to do a write up....?

I don't know how to surf. But I am an Olympic-level hanger-outer.
Regards
Timo

[mogogear]

I don't know how to surf. But I am an Olympic-level hanger-outer.
Regards
Timo

Hey we would be there to learn right?? All in the name of science.The only surfin' I do is on this keyboard. Come on Dan , order us an Achille to test!!!! Bags are packed!!! I know with a screw driver/ leatherman / adjustable end wrench and some duct tape- we can easily figger' this rascal out

[timo888]

A simple question. How is the boiler filled with water? I don't see clearly how the water makes its way from tank to boiler. Does the tank-water exit through #21-#20 and then flow into the boiler via #17?

I'm beginning to think this machine should be called the Gaggia Escher.
Regards
Timo

[Staffan]

You never answered the question about what you observe with the PF removed:

Oh...didn't see the question until now. With portafilter gone and lever raised, there will be no water emerging from the shower except for some drops. I have to push the lever down to get any pre-infusion at all.