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

Randy G. wrote: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.

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.

erics wrote: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.

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.

erics wrote: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.

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?

jgriff wrote: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