Bad cracks and donut + channeling with Elektra Microcasa a Leva

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StefanoB

#1: Post by StefanoB »

I am still new with the Elektra, and with espresso in general.

I have now a bottomless portafilter, and discovered with it my extraction are horrible :wink:

Here is below a few photos of my setting, a typical extraction I get, and puck afterwards.

My grinder is Commandante C40 with Redclix.

I am currently using Illy intenso, batch just bought to Illy Cafè they have received last week, new box opened (roast date is July 2020 but beans are kept under void).

My routine is to grind, transfer from the C40 dosing glass cup to basket+dosing funnel (I prepare the puck directly on the basket, the pf is on the group head heating in the meantime), stir vigorously and achieve an even surface with the Londinium-type WDT, do two gentle vertical taps on the mat to settle grounds a bit, then create a flat surface with the OCD-type tool (from bplus, made for La Pavoni pre-mils), tamp straight and direct (moderate force, just stop when I just feel the coffee bed start to resist, no fancy moves such as nutation or rotation after) with the stainless steel 49.5mm tamper on the photo below.

I am using Elektra's stock basket. I have done testing to determine, using a 20 cent euro coin, that 13.0g is the maximum dose for this basket and this specific coffee (at 13.5g the coin leave a mark in the puck when fully locking the pf, at 13.0g the puck have no mark at all after locking - unlocking). But to be 100% sure I don't have any updosing issue whatsoever I am using now 12.0g in this basket.

In the extraction I share the photos, I am pre-infusing 18'', I start to see coffee appearing (on the side, typical donut-type extraction) after 8'', first droplets in the cups at 15-16'', then I let the lever going up at 18''. I terminated the extraction by removing the cup after 42'' overall (therefore extraction time was 24'') to get a ~20-21g espresso cup.

Coffee taste was ok, not as good as in Illy Cafè but rather close to (these types of dark roasted blend and the lever machines are very - very - forgiving... :lol: ), but there is a little unpleasant "channeling" after-taste that I don't get at all when I get the same espresso in Illy cafè.

I precise I have taken out the portafilter some ~1'30-2' after the end of the shot. So no pressure any more to mess up things.

Last, I should say that I also have a Cafelat Robot in my office (the MCAL is at home), with a C40 grinder and same WDT tool, and with the same Illy intenso (same roast date but not same box) and a similar routine (grinding in C40 cup, transfering in the Robot basket, vigorous stir with WDT, gentle taps for settling, leveling surface then tamp with the Robot's levelling tamper), and a 15.6g dose, I do not get particular extraction issues (no donut or significant channeling, puck inspection is irrelevant with the Robot).


Do you have any clue of what is going on here, and how to fix these very bad issues with the MCAL?...



- tools I am using:




- after 12'' pre-infusion:




- after 18'' pre-infusion (when I release the lever):




- after 6'' extraction (24'' total time):




- after 18'' extraction (36'' total time):




- puck after removing (about 1'30-2' after end of the shot):

Stefano

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baldheadracing
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#2: Post by baldheadracing »

I haven't used illy in years -and never in an MCaL - so I can't comment on that.

Assuming that your boiler pressure is under 1 bar, your shower screen could be the cause, although I would say that's long shot. The water coming out of the shower screen should stream out like the first 20 seconds of this video by @fransg http://www.youtube.com/watch?v=Q-n_WYf5CFk
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StefanoB (original poster)

#3: Post by StefanoB (original poster) »

baldheadracing wrote:I haven't used illy in years -and never in an MCaL - so I can't comment on that.

Assuming that your boiler pressure is under 1 bar, your shower screen could be the cause, although I would say that's long shot. The water coming out of the shower screen should stream out like the first 20 seconds of this video by @fransg http://www.youtube.com/watch?v=Q-n_WYf5CFk
My MCAL is brand new. I have taken out the shower screen anyway to inspect it, and it was clean. Do you think IMS shower screen may improve on this doughnutting issue?

Another test today. I have increased dose to 12.5g and tamped hard this time (adjusting grind accordingly). Rest of my protocol unchanged. No cracked puck this time, but still a "beautiful" doughnut extraction...
Stefano

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baldheadracing
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#4: Post by baldheadracing »

Coincidentally, I just ordered new piston seals, shower, group gasket, etc., from espressocare.com and decided to go with the IMS shower. I'll post when I try it. (I'm not expecting anything over a good version of the stock shower screen.)

I myself don't worry about donut extractions given the double basket's design, but I am making Cappa's. I'll usually go with the stock single basket for the rare times I use the MCaL for straight espresso.

ETA: My MCaL is 35 years old - my experience may not be applicable to the latest production.
What I'm interested in is my worst espresso being fantastic - James Hoffmann

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StefanoB (original poster)

#5: Post by StefanoB (original poster) »

baldheadracing wrote:Coincidentally, I just ordered new piston seals, shower, group gasket, etc., from espressocare.com and decided to go with the IMS shower. I'll post when I try it. (I'm not expecting anything over a good version of the stock shower screen.)
Thanks, that would be interesting to know.

baldheadracing wrote: I myself don't worry about donut extractions given the double basket's design
What do you mean? That the double baket's design compensate for the dounut issues?

I am wondering if a convex tamper might not help with the issue.
Stefano

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baldheadracing
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#6: Post by baldheadracing »

StefanoB wrote:... What do you mean? That the double baket's design compensate for the dounut issues?

I am wondering if a convex tamper might not help with the issue.
Sorry, I wasn't clear. The stock basket has holes at the edges so extraction starting at the edges happens at least some of the time for me. When I make a double on the MCal, the espresso is going into a cappuccino. The milk dilutes the impact of extraction, so I enjoy the drink regardless :) .

I do use a convex tamper with the single basket - but I have never used that tamper with the double basket. Hmm.
What I'm interested in is my worst espresso being fantastic - James Hoffmann

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StefanoB (original poster)

#7: Post by StefanoB (original poster) »

baldheadracing wrote: I do use a convex tamper with the single basket - but I have never used that tamper with the double basket. Hmm.
With the single it makes sens. With the double in principle we do not need one, but as there is this issue which persists... Where did you by yours? I haven't found many options for a convex tamper with a 49mm / 49.5mm base (actually, none yet :wink: ).

After having done some more research in this and other forums, I have found two extra ideas that may be worth trying:

1) finger tamp at 12'+3'+6'+9' O'Clock at the same time (4 fingers), then 1'30+4'30+7'30+10'30, with fingers on the very edge of the tamper to achieve proper seal of the outer ring of the puck (that means also moving to light tamp) ;

2) distribute (with my Londinium-like tool) in a circular way (from outer ring to center of the basket?) in order to achieve a slight concave distribution (slightly less height in the middle and little more in the outer ring).

I may try that with and without using the OCD-like tool. Problem of number 2) is to be repeatable...

If nothings solve the issue permanently I'll consider the convex tamper.
Stefano

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baldheadracing
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#8: Post by baldheadracing »

You might be able to find an online shop that still has stock of the Espro calibrated tamper in 49mm convex. Also, I just noticed that H-B sponsor Prima Coffee has a 49mm convex https://prima-coffee.com/equipment/prima-coffee/atb-ss
What I'm interested in is my worst espresso being fantastic - James Hoffmann

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StefanoB (original poster)

#9: Post by StefanoB (original poster) »

Thank you, the H-B convex tamper looks nice :-)

Today a few tests with a concave distribution, and the finger tamp at the extremity of the tamper (4 fingers, at 12 - 3 - 6 - 9 O'clock, and then 1'30 - 4'30 - 7'30 - 10'30).

With a slight concave distribution: still dounuting, but it seems for a little less time.

With a pronounced convave distribution: coffee start to appear the the outer ring (dounuting...) and in the center at the same time, leaving a void middle ring for the first few seconds. It has also lead to channeling in the center, and a cup that was not so good, too bitter (same setting otherwise).

Because the dounuting is still present even with a pronounced concave distribution, it seems to me that the issue might not be related to distribution, but to proper seal of the puck.

I use a 49.5mm tamper, but the baskets I use (Elektra's stock and Strietman) avec 49.8mm. So what about using a 49.7mm tamper for instance: would it enable a better seiling of the puck?

Otherwise, what are the techniques to best seal a puck?
Stefano

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baldheadracing
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#10: Post by baldheadracing »

Speaking of tampers, as you're in the EU a tamper from tidaka.net might work out better for you. They have a 49.1 convex base available. (I've purchased from tidaka.net over the years and recommend them.)

I just re-read the thread and there isn't much difference in our prep that could affect donuts except that I tamp harder. You may not be tamping hard enough to seal the puck against the sides of the basket. I suggest that you try a 15kg or so push on the tamper after the puck has been fully compressed. If that helps then you can adjust lighter as desired.

Good luck! I know that espresso frustrates me sometimes!
What I'm interested in is my worst espresso being fantastic - James Hoffmann