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Thread: Constant outer edge extraction from one particular type of bean.

  1. #1
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    Constant outer edge extraction from one particular type of bean.

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I'm getting an extraction that starts at the very edges of the basket and I doubt ever comes from the centre section of the puck (difficult to tell when the edges cumulatively form in the middle after 10 or more seconds).



    I've tried redistribution to level out the dose, but nothing works. What's weird (to me) is that it only happens with one particular type of brand of bean, if I switch to another blend I still get the outer edge starting, but the extraction is very even shortly after.

    https://youtu.be/ZJv8gWpuVUo

    It's not a problem, I just simply won't use this blend anymore, wasn't a fan anyway, but I'd love to know what it is, if possible.
    Last edited by BobSac; 4th April 2019 at 08:50 PM.

  2. #2
    Mal Dimal's Avatar
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    G'day mate...

    Might be an optical illusion but the bottom of the basket appears to be slightly convex.
    If it is like this in reality, the dose in the basket will be distributed more towards the centre of the basket thereby creating less depth of tamped coffee around the edges, therefore less resistance for the water to penetrate...

    Sounds good in theory anyway.

    Mal.

  3. #3
    Senior Member Jackster's Avatar
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    I was thinking similar. Maybe a convex tamper would fix it. I have a convex and a flat, and I think it makes a little difference. Maybe try the nutating tamp to get a bit harder to the edge tamp

  4. #4
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    Must be the distortion of the lens, took the basket out and put it on a flat bench, it's flat. It's the standard genuine Rancilio basket (and naked group handle).

    Switched back to another blend and problem solved.
    Very weird.
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  5. #5
    Senior Member noonar's Avatar
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    Quote Originally Posted by BobSac View Post
    Must be the distortion of the lens, took the basket out and put it on a flat bench, it's flat. It's the standard genuine Rancilio basket (and naked group handle).

    Switched back to another blend and problem solved.
    Very weird.
    Hi BobSac,

    I get the same thing - sometimes - with certain beans/roast levels and again sometimes it slightly worsens with the age of the roast, it may be due to the oils in that particular bean/roast and water being a path of least resistance beast tends to find an easier flow around the rim of the puck and then spreads from there. One thing I try, which does help, is to grind slightly coarser and (sometimes) tamp substantially harder. As you mentioned, only with certain beans/roasts, switch to another and the problem goes away. I'm using a (flat bottom) VST and they can be finicky anyway, my regular tamp is very light. Good Luck.
    Dimal likes this.

  6. #6
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    That works!

    A step coarser and a higher dose and slightly firmer tamp.
    Wow, I wouldn't have thought the characteristics of the extraction would change.

    I was using a 16g dose (in a triple 21g basket) but now I'm using a 19-20g dose (same basket).

    Perhaps it's my grinder (still using a sunbeam EM0480).

    I won't be buying these beans again, they aren't bad but not great either, but sure was interesting to solve this, thanks!
    Dimal likes this.

  7. #7
    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by BobSac View Post
    That works!

    A step coarser and a higher dose and slightly firmer tamp.
    Wow, I wouldn't have thought the characteristics of the extraction would change.

    I was using a 16g dose (in a triple 21g basket) but now I'm using a 19-20g dose (same basket).

    Perhaps it's my grinder (still using a sunbeam EM0480).

    I won't be buying these beans again, they aren't bad but not great either, but sure was interesting to solve this, thanks!
    Great to hear it's solved . I was also puzzled about the different beans acting differently, but just a little observation, a 16g dose in a 21g triple basket is a reeeeally low dose, far too low reckon, and I think perhaps there was too much space in the basket for the water to just go nuts. Not to mention how fine a grind you would have to go for that dose, the water was probably just thinking "nahhhhh I'm just goin round!" (Water being very resourceful like that :P)

    Definitely upping the dose to around what the basket size is would help, good stuff!

  8. #8
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    With my sunbeam, I'm unfortunately unable to get in between steps required to do so.

    Macap M7D is on the way though and that should solve that issue.
    Dimal likes this.

  9. #9
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    Quote Originally Posted by Dimal View Post
    G'day mate...

    Might be an optical illusion but the bottom of the basket appears to be slightly convex.
    If it is like this in reality, the dose in the basket will be distributed more towards the centre of the basket thereby creating less depth of tamped coffee around the edges, therefore less resistance for the water to penetrate...

    Sounds good in theory anyway.

    Mal.
    A quick addition to that - hit any lower quality basket with 9 bar pressure and a restrictive coffee puck and it will distort and become noticeably convex, even though it is flat at room temp / pressure.
    Dimal, cafelazio and BobSac like this.

  10. #10
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    Wow, didn't know that.

    I may upgrade the basket just to see if I get an increase in quality and/or consistency.

  11. #11
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    Quote Originally Posted by BobSac View Post
    Wow, didn't know that.

    I may upgrade the basket just to see if I get an increase in quality and/or consistency.
    I admit to a bias, however I would recommend VSTs if you want to upgrade. Ask Yelta for a differing view or just look up the VST basket thread.

  12. #12
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    Behmor Brazen - $249 - Free Freight
    I'll get onto a VST basket soon, just to muck around and see if it actually makes any noticeable difference, I'll watch until I'll got all other areas of the process consistent.

    Right now I'm testing different size baskets, I'm keen to get a single working well. It's tastes OK, not as good as my doubles.

    Dimal likes this.



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