Can anyone explain preinfusion on the E61?

[bigdog002]

I've asked several people about the mid-position of the lever and whether or not to use it before a pull. All have dismissed it as a worthless practice. I would like to hear if anyone manually preinfuses.

When I lift the lever on my Anita to mid-way the pump turns on but it seems a bit less noisy than normal and my pressure gauge displays pressure (seems to be equal to the blind pressure). I do understand about the gauge reading relative to the position of the T. When I lift the lever to the top I can hear the pump growl fully as it starts pumping water for a shot.

-- What exactly is happening when the lever is at mid-point?
I've looked at the diagrams dan provided, but I'd rather have it explained in simple english.

- is there any benefit to holding the lever at mid-point for any length of time? and does this time count against the total shot time?

- the sound of the pump at mid-point scares me for some reason .. makes me fear I am going to burn it out. Is this dangerous?

I've been told the machine designers count on the vibe pumps characteristic (slowly starting flow) as preinfusion .. is this correct?

If all this is covered elsewhere forgive me and direct me to it. I'd really like to understand this 'feature'? of the E-61 that nobody seems to use or discuss.


Chris

[cafeIKE]

In the mid position, both the inlet out outlet valves are closed.

If the pump turns on in the mid position, the switch is misadjusted. The pump should start just as the inlet valve opens. If your gauge reads the blind pressure, the pump is pumping against the upper valve and simply cycling water thru the OPV.

The e61 pre-infuses as the valve fills.

[bigdog002]

In the mid position, both the inlet out outlet valves are closed.

If the pump turns on in the mid position, the switch is misadjusted. The pump should start just as the inlet valve opens. If your gauge reads the blind pressure, the pump is pumping against the upper valve and simply cycling water thru the OPV.

The e61 pre-infuses as the valve fills.

Should I be concerned about the misadjusted switch and can I adjust it myself?

[Randy G.]

On the VBM's, the E-61's midpoint lever position opens the HX and water path and allows the pressure of the heated water in the HX to be released into the brewhead and onto the coffee. I believe I have heard that referred to as a passive pre-infusion. I don't use it because the slow ramp up of pressure over the first 8 to 10 seconds that is designed into the group takes care of the preinfusion (IMO). Additionally, if you have flushed the group to bring the temperature down before pulling a shot, there is little if any built up force to deliver any significant amount of water to the coffee... IMO.

From your description, if that happened to my machine, I would assume that the switch that energizes the pump is being closed too early in the lever's arc, but I do not know how the Anita is supposed to operate— just guessing based on how my E-61 operates.

[HB]

If all this is covered elsewhere forgive me and direct me to it. I'd really like to understand this 'feature'? of the E-61 that nobody seems to use or discuss.

Then you should check out the FAQs and Favorites Digest. It even includes obscure topics like Is there a purpose for the E61 middle brew lever position? under the heading E61. If you really want to understand the internals, there's also detailed discussions using Lino's CAD drawings.

I've been told the machine designers count on the vibe pumps characteristic (slowly starting flow) as preinfusion .. is this correct?

It depends on the group design. For E61s, the expansion chamber does the job. If the designers were concerned about excessively fast pressure ramp up, they'd add a gicleur (a small orifice in the grouphead to slow the onrush of water).

Should I be concerned about the misadjusted switch and can I adjust it myself?

If you want to play with passive preinfusion using the mid-position, I suppose you could, but I wouldn't bother. Awhile back I toyed with the rotary Vetrano using line pressure to presoak the puck at the lever's mid position and wrote about it in The Secret Life of Ristrettos, but I don't consider my observations in that thread adequately tested to be considered reliable. Since your Anita doesn't have line pressure, that option isn't open to you. The mid position will spittle forth a half ounce or so of water and then stop until the vibe pump engages.

[bigdog002]

Thank you all.

I guess I won't worry about it. As long as the pump kicking in 'early' in the lever path won't do any harm. I might give Chris' a call tomorrow and talk to one of the techs about it.

Off I go to read the thread Dan provided.


Chris

[erics]

When the lever is in the fully down position, there is a clearance between the cam surface and the "button" on the pump switch of ~ 1/16" or 1.5 mm. Engaging the pump when the lever is in the mid-position, as Ian said, most definitely shows that the switch is misadjusted. I suspect that the switch's locknut is a tad loose.

It does no physical harm to the machine but DOES DO harm to a flushing routine because Anita's blind flow passes THROUGH the heat exchanger. See below:

The image of the E-61 group is copyright 2005 by Verna Design, Inc. It is shown in the brew position.

[bigdog002]

It does no physical harm to the machine but DOES DO harm to a flushing routine because Anita's blind flow passes THROUGH the heat exchanger. See below:

I played with the lever more, if I raise it slowly I get a 'click' , no pump, at the very bottom of the mid-position. I assume this is proper operation. If I raise the lever slightly to the top of the mid-position the pump engages. It's not as out of adjustment as I first thought.

I'm confused how it would hurt my backflush. I engage the pump as normal during a backflush ... ?

[bigdog002]

Ok, I've made another discovery ..

When I pull OUT (towards me) on the lever as I lift it does not engage the switch behind the lever (pump) at the mid-point, however at this point it does NOT open the valves as it should. At this point, if I put slight sideways pressure on the lever toward the group head the valves open up and the pressure is released. Neither of these require much force at all, just slight pressure on the lever out and in at the same time.

I talked to a tech at Chris's .. he is sending me a spacer to install and he says it should fix that problem.


Chris

[erics]

It is not easy to explain because temperatures can vary quite a bit depending upon how much you flush and whether or not this is the first shot after an hour's warmup or the 2nd shot a minute or so after the first AND whether or not your reservoir is 90% full or 90% empty.

It seems, now, as though your machine's pump switch is properly adjusted after all.

HOWEVER, if this were NOT the case, you would be cooling off the hx and NOT passing any water through the group during this "misadjusted" flush. As you can probably imagine, there are numerous ways in which Anita (and other similar machines) can be operated with the goal being to deliver a consistent water temperature to the espresso grounds regardless of when the shot is produced.

Good explanations are contained here: http://www.home-barista.com/hx-love.html

[bigdog002]

I understand Eric, thank you. Each time I read your posts I gain more insight on the inner workings of these E-61s, even if it takes me a week to decypher them to the point of understanding

I'm just relieved it's a such a minor matter. The thought of shipping this back and being without for 10 days or so actually shuts down my brain. If I think about it I just collapse in a pile right where I stand.


Chris

[cafeIKE]

On the VBM's, the E-61's midpoint lever position opens the HX and water path and allows the pressure of the heated water in the HX to be released into the brewhead and onto the coffee.

I installed my Digital pressure gauge, locked in a blind basket and set the lever to the mid position.
After 10 minutes on a dry blind basket, the pressure had not changed at all. Only a few drops of water from condensation, nowhere near enough to infuse a puck, was in the basket. If the test were performed before shots are pulled, the basket would be dry.

I filled the blind basket by running the pump to full pressure and lowered the lever to the bottom position to Zero the gauge. After 10 minutes with the lever in the mid position, the gauge read -0.07bar due to the the cooling of the water in the blind basket.

I then placed a dry blind basket on a stand under the group for zero backpressure on the group.
The amount of water captured into an open dry blind basket with the lever in the mid position for 10 minutes, Zero.

The mid position on an e61 does nothing. Nada. Zip. Zilch. Only if the lever is moved so the cam engages the valves will water flow. Whether the pump runs before or after the valves open is a mechanical adjustment.

[erics]

On the Quickmill machines, it's a different story. Or perhaps, I better say, on my Anita, it's a different story.

When I lift the lever from the fully down position to the mid-position (audible click and you can certainly feel the detent), the hx is open to the group and any pressure build-up in the hx due to expanding water is immediately dissipated and water flows through the group. If I manually activate the pump (by depressing the "button" with my fingers), it's as if I were flushing the group - water flows.

I would say that this is (at least on the QM machines) the way it is intended because this would allow one to pre-pre-infuse if they were connected to line pressure e.g. the Vetrano.

Of course, I'll be anxious to hear how that dual boiler, rotary Vibiemme works for you.

[HB]

The mid position on an e61 does nothing. Nada. Zip. Zilch. Only if the lever is moved so the cam engages the valves will water flow. Whether the pump runs before or after the valves open is a mechanical adjustment.

I just tried it and confirm the Vibiemme is as you describe, i.e., water does not flow when the brew lever is at the midpoint detent.

When I lift the lever from the fully down position to the mid-position (audible click and you can certainly feel the detent), the hx is open to the group and any pressure build-up in the hx due to expanding water is immediately dissipated and water flows through the group.

This is consistent with what I found with other Quickmill models like the Vetrano, i.e., water does flow when the brew lever is at the midpoint detent. Looks like you're both right.

[cafeIKE]

On the Quickmill machines, it's a different story. Or perhaps, I better say, on my Anita, it's a different story.

Perhaps we need a definition of positions :
Upper: When the cam lobe contacts the upper valve to allow brew water into the group

Mid: The neutral position reached when neither cam lobe contacts the valves.
On the Vibiemme, the "mid" position has quite a bit of travel and is much freer than the upper or lower positions.

Lower: When the cam lobe contacts the lower valve to allow release of the brew pressure.

[erics]

Absolutely, I agree with your definitions; its just that the QM machines apparently give a little nudge to the brew valve when the lever is in the mid-position. And, it seems, a little nudge goes a long way.

If I operated the Anita lever with my eyes closed and were going strictly by feel, I would agree with you 100%.

However, that's not what happens here on the RIGHT coast and the only guys who really know the story are cutting Z's because it's 2:00 am over there.

[jesawdy]

Absolutely, I agree with your definitions; its just that the QM machines apparently give a little nudge to the brew valve when the lever is in the mid-position. And, it seems, a little nudge goes a long way.

Yup, same on the Alexia. I've used this to wet a cleaning rag just after turning the machine off. Move the lever to mid position and you'll get a nice dribble from the grouphead for a few seconds... just enough for a quick polish.

[jgriff]

And my Anita is slightly different in the way it operates. I can raise it to the middle position with no flow at all; however, if I apply slight upward pressure I do get flow from the HX loop. I use this trick when I scrub the group with my Pallo tool. It's funny, though . . . there's a very fine line (on my machine) between getting a little dribble and engaging the pump, and it seems to vary depending on when I'm using it. Sometimes nothing comes out but the pump engages and builds pressure, presumably without filling the chamber at all. Then other times I can get it to dribble without hitting the pump switch. I haven't noticed, but I guess it could vary depending on how hot the machine is and how much pressure is in the HX loop.

So maybe every machine, even similar ones from the same manufacturer, has its little quirks?

[luca]

So maybe every machine, even similar ones from the same manufacturer, has its little quirks?

The lever engages a switch. On many of the machines that I have seen, you can adjust how far out from the machine this switch sits and, consequently, when the pump is engaged. It is entirely possible that someone's switch has slipped and it shouldn't take too long to pull the cover of the machine and adjust it.

As for the benefits of preinfusion, that's another story. Without exception, every single person that I know who has a synesso doesn't bother with the middle position. A few years ago when I experimented with it, I found it oddly satisfying to be able to preinfuse at line pressure until I saw beads at the bottom of the naked PF basket, then slam it into full pressure. However, I don't think that it made the shots taste any better. It might have made them taste a little richer.

Over the past few years, I have found that shots with a longer preinfusion time tend to be richer in body, but lower in clarity of flavour. Most of the domestic machines that I have used have a very long preinfusion time already and I think that it is detrimental if you prize shots with clearly defined flavours, so, personally, I wouldn't be worrying too much about adding PI time with the middle position. However, if you like ristretto type shots it might be worth messing around with.

Cheers,

Luca