Hi,

Well, this is almost embarrassing, since getting a naked PF my confidence in my espresso skills has taken a hit.
When extracting the shot it's not uncommon for a patchy extraction across the bottom of the PF and none of the "espresso porn" cone development to occur. The shots still TASTE good.

I've tried down dosing, grinding finer, coarser, WDT, no-WDT, different beans, closer to roast, further from roast, even my hand grinder instead of my Mazzer. I've switched screens (due to maintenance).

I haven't tried a different basket (I have the VBM basket somewhere).

I've found if I extend the normal e61 'preinfusion' by allowing 4bar of pressure to build, then moving the lever to the middle position until there is even seeping through the basket (approx. 30-40s), it improves the shot at the start. I guess this is like a ~45s pre-infusion instead of the normal 6-7s? of an e61.

• Espresso machine: Vibiemme Domobar Piccolo (750ml SBDU) PID set to 93.5deg C, 9bar (Scace verified), IMS screen
• Basket: VST 20g ridge less
• Tamper: Pullman Nexus 58.4mm
• Water: tap, <50ppm GH, <50ppm GH
• Grinder: Mazzer Mini E (64mm burrs), burrs are 18 months old, so that would be approx. 20kg through their 300-400kg expected life. Recent burr clean completed.
• Other grinder: 1zpresso J-max

Images are screenshots of a video of not the worst shot. Looked bad in the PF, great floral notes on the nose and palate from a great Ethiopian from a fantastic local roaster.

Any insights welcomed.

Images should be in sequential order of shot development. I can dig out worse ones if needed.

Jeff wrote:Others may disagree, but that looks a lot like what I'd expect from a medium or medium-light SO.

That makes me feel better as medium through med-light is all I drink! If I posted this on r/espresso I'd be crucified.

_Ryan_ wrote:I've found if I extend the normal e61 'preinfusion' by allowing 4bar of pressure to build, then moving the lever to the middle position until there is even seeping through the basket (approx. 30-40s), it improves the shot at the start. I guess this is like a ~45s pre-infusion instead of the normal 6-7s? of an e61.

I would suggest either loosening the grind with this coffee and this dose or try other coffees.

Is your machine direct plumbed?

Not direct plumbed, but middle position (for this test, i don't always do that) holds pressure.
Darker roasts will extract a lot prettier now that I think about it, but I've had one darker roast in the past maybe 6 months?
Loosening the grind leads to a decrease in extraction quality in terms of flavour and aroma.
I drink lots of different beans as I rotate through different SO's or 2-bean blends, all roasted on the lighter side of medium, as is the norm for Melbourne's specialist roasters.

How much coffee in the basket and how much yield?
How tall is the IMS screen?
If you lock in the pf with a US nickel sized coin, ≈20 x 2 mm, and then remove, how big an imprint does it make?

The middle position is a ZERO-pressure coffee soak, not pre-infusion. It's uncontrolled, non-repeatable and IMO, a FWoT.
Pre-infusion was the rationale behind the e61 design.

e61's make great espresso with a practiced hand on the controls. They don't make the same espresso as a Slayer or GS3 or Decent or Verve or any lever, but they certainly hold their own. For cruising, it's hard to beat a '61 Bonneville Convertible. Gimme that any day over any current plasti-fab!

Aim for an even 'bloom' on the basket, regardless of dose. The cone should center within a few seconds. Only when making uber-ristretti are multiple cones permitted, but the basket should have no blank spots.

Jeff wrote:I never had much luck with the middle-position "preinfusion" claims with a reservoir machine. It seemed to be far too uneven and unpredictable. It was more like a dribble than something suitable for evenly wetting the grinds.

I typically do 10 seconds of the middle position "pre-infusion" or "soak" or whatever you want to call it. Then I activate my pump and pull a 1:2 at a 14 g dose of a medium light SO in about 35-40 seconds. I know I'm extracting a lot, but it's how I get the best results for my taste. I find that the initial 10 second pre-infusion helps with consistency, and reduces dead spots in my VST. When I don't pre-infuse, my shot goes over 40 seconds at the same grind and the pull isn't as consistent. So more than anything else, it oddly HELPS with my consistency. I attribute that to wetting my grounds thoroughly (water comes out of my shower screen quite evenly) allowing things to bloom so there's more uniformity in my puck. Just throwing my experience out there with this technique on the e61. It's been beneficial for me with what I do.

_Ryan_ wrote:The shots still TASTE good.

Then why drive yourself nuts and obsess over a good looking extraction? Is this not the end goal?

On a resavour driven E61, the middle position does nothing. You will get some water just because of thermal expansion of the water in the heat exchanger or boiler. You need a plumbed in machine for pre infusion. Then the middle position will flow water at your mains pressure. Skip it and just go full on.