Olympia Cremina - air bubble in every extraction - Page 3

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dsc (original poster)
Posts: 1166
Joined: 17 years ago

#21: Post by dsc (original poster) »

This is how I fill the basket:

https://www.youtube.com/watch?v=fUuFC3WZpEA&vq=hd720

as you can see there's no clamping.

Afterwards I do a single light downwards tap and tamp. I've played around with various baskets today, got two currently, the shallow / standard one which came with the machine (this holds around 16g) and a deeper one, might be an Elektra (it's the one from OE, holds 20g maybe?). On the deep one I got really bad side channeling, much more than on the shallow one. Curious if raising the lever and head space have anything to do with this.

Beans are well rested, I was getting bubbles on all shots with all beans, from super fresh to 6 month old ones, but that was due to temps, as I was reading close to 100degC on the group. As for sour vs temps, I've read somewhere in the Cremina temperature study, that actually high temps might as well be sour, which is something I've experienced before (on light roasts). Currently I'm 80% sure this is down to underextraction, as there's a specific harshness lingering in the back which I always connect with underextractions.

Rgds,
T.

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aecletec
Posts: 1997
Joined: 13 years ago

#22: Post by aecletec »

I can't really comment on the Cremina particulars but it does seem strange.
With the puck preparation, you don't level the grounds? They come out beautifully but you could have a puck of uneven density if the grounds surface isn't flat before tamping...
I have noticed effects of lever raising too quickly, so it's worth experimenting with? Good luck!

IMAWriter
Posts: 3472
Joined: 19 years ago

#23: Post by IMAWriter »

Tom...there are a lot of ways to grind into a basket, but if it were me, with the time it takes to do that grind, there is just so much chance of uneven distribution, due to the constant movement you're undertaking.
I would get an OE http://www.oehandgrinders.com/OE-Ipanem ... _p_26.html

You won't regret it. Just hold the PF steady under the grinder. When done, do a WDT. Cremina's love it. You'll find you have more "feel" as you adjust your lever pressure whilst observing the pour. Also, if you have a flat bottomed tamper, I found it worked best with the smaller basket. I highly recommend Richard Penney's specially made tamper for the Cremina. It perfectly fits both OEM and MCAL double baskets, and has a thinner piston, which makes a level tamp so much easier. As to the tamp, try a lighter 10 lb tamp.

Hope this helps.

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dsc (original poster)
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#24: Post by dsc (original poster) »

Chris / Rob,

I do indeed level the grounds, I've also tried WDTing the lot, but nothing seems to help. Dropped the dose to 14g, light tamp and it still side channels rather badly now. Not sure what is going on as it was fairly good so far with the Cremina...

The tamper I'm using is flat and fits the basket really well as it's custom made. I guess I need to take the covers off the grinder and see if the alignment is spot or not (last time I re-assembled and checked the runout was 0.01mm, although in fairness I did not check the parallelism this time).

T.

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aecletec
Posts: 1997
Joined: 13 years ago

#25: Post by aecletec »

I somehow managed to miss this, sorry.
That's definitely a tricky problem. The only other distribution-related thing I'd look at is grinding into a container, stirring/whisking and then transferring into basket to see if it helps.

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