Hello

As of recent I've started to play with the 16gr basket in my open portafilter on my Dalla Corte Mini.

but I am not sure what exactly is going wrong...

if I grind too fine (by little) the coffee almost won't come through... it only will dribble randomly at certain spots beneath the basket...

if I set it little coarser coffee flow seems fine, but the extraction is uneven... resulting in two or three "exit points" at the basket and it usually Sputters water/coffee all around... making a mess.
the coffee is "Ok" - read "not great, but drinkable (it could be much better)".

The one thing which annoys me most is that I started to play with the bottom less p/f when I started not to get the desired crema anymore... (don't know if it's my new coffee... or something with the machine (doubt it)).... so I thought the bottom less p/f would be a good way to check what's happening,... and the results are described above.

now I've tried a lot... but the results are far from consistent.

I also checked the brewing pressure inside the p/f using a special porta-filter pressure gauge I built (0-15bar gauge on a 3/8 T-Elbow)... and the dalla corte is dialed in at 9,8-10 bar) (which seems fine imho).
Temperature is very consistent set to 95°C (so I guess I've got the basics still right).

One thing I was wondering if water hardness and resulting scale could have some influence... I'm trying a different type of water at the moment...


any tips and hints VERY welcome

thanks

Have you read this post yet?

ferrum wrote:The one thing which annoys me most is that I started to play with the bottom less p/f when I started not to get the desired crema anymore... (don't know if it's my new coffee... or something with the machine (doubt it)).... so I thought the bottom less p/f would be a good way to check what's happening,... and the results are described above.

How old is your bean?

ferrum wrote:now I've tried a lot... but the results are far from consistent.

As old man said, practice makes perfect. I do have the same problem before, so I invite my friends every week for a full months just to improve my espresso. It does improve my espresso alot, even it burns out my wallet

Being how I am... (I tend to lean towards "perfectionism" "slightly " ) I just spent a good amount of time in front of my coffee-setup playing around with things...

and I tried "stirring" the espresso grounds once I had them inside the portafilter as described here: http://www.home-barista.com/weiss...ion-technique.html

the result was instant improvement... not perfect, but a hell lot better...
then I started varying the grind... and voila, even more improvement...
it's not yet "perfect" but closer... a lot closer.
and the espresso... as yummy as it should be


btw: the beans should still be ok... no older than two-three weeks.
maybe it's also due to the fact that humidity levels have increased here since spring started (winter-climate is VERY dry)... so there's more "clumping".


still any more tips, are of course welcome as usual.

thanks

1 - the way you adjust extraction is by changing the grind. The grind is not a constant.

2 - two to three weeks old is stale with many coffees.

ferrum wrote:btw: the beans should still be ok... no older than two-three weeks.

Is this measured time from the roast date?
If the actual roast date is not known, then the beans are usually too old before you open the bag.

Can you buy beans from a local roaster so you will know the roasted-on date?

Uneven extraction are caused by poor technique, nothing else. However, the extent of good technique required for properly flowing shots varies from machine to machine, grinder to grinder, and coffee to coffee. Personally, I give the DC Mini the donut-king booby prize when it comes to nice looking extractions. Try using the bulb-handle of your tamper to make a hole in the center of the puck prior to leveling and tamping to encourage earlier flow from the center.

No crema is caused by old coffee, pretty much nothing else; with fresh coffee, you should get at least decent crema on any extraction short of a complete catastrophe.

I've done quite a lot of experimentation with my DC Mini and documented it on this board. As Jim Schulman said, it likes to make donut-shaped extractions, and will make lots of them until you find the right combination of grind and weight.

The magic combination for me turned out to be 15 g. of a superfine grind. No needle stirring or other rituals are necessary. You should get a nice, even extraction nearly every time. But, be sure to lock the portafilter in very tightly (steady the machine with your right hand), or the pressure will turn it out of the brewhead.

And, as others have said, be sure your coffee is reasonably fresh.

Interesting as that contradicts what Jim said about making a depression.

Thanks for all the replies!

1. Coffee... It is from a local roasted, freshly roasted... The Problem is that I had the original packing at my machine shop, so when I posted I did not exactly remember the roast date - but I knew it was between two to three weeks. (it's called "Bonga Bonga" and is an Ethiopian "Rain Forest" coffee... pure arabica... no blend - very tasty....)
But I suspect that the container I used for storing isn't "good"... as the beans I have at the shop tend to yield the better coffee (although it supposedly is from the same batch, unless I mixed something up).

2. Today opened up a new pack (I buy 'em in 250gr packages from my roaster)... and Crema was back again... lovely...


@another_jim
Thanks also for the tip about using the bulb-end of the tamper... this really solved the donut problem...


@marshall
I'll give that a try... but I need a more precise small scale to measure it exactly.


@HB
Pardon my ignorance but what exactly to you mean by "nutate" ???? as far as my english goes, but I understand "nutate" as to make a circular "wobbly" motion or something along that line...
if you don't mind, but please go in-depth about what exactly you mean with nutate in combination with a DC Mini and coffee...