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  • A_M
    replied
    Re: EM6910 stuck puck

    Originally posted by 57495D1B0 link=1226019023/33#33 date=1291169381
    Originally posted by 617465746364110 link=1226019023/0#0 date=1226019023
    I have developed a new problem with the puck sticking to the shower screen of the EM6910. I can get it off by loosening the PF and using the manual button to deliver a one or two second burst of water.

    What are the likely causes for the puck sticking to the shower screen?
    Ive been having the same problem. Tried all sorts of solutions starting with a good clean, then varying the dose and the tamping pressure. Every second puck seems to stick.
    Has anyone tried removing the plastic insert that sits under the filler basket?
    I never had this problem with other machines, just with the Cafe series Sunbeam. Apart from that Im happy with it and its more reliable than my Gaggia.
    As stated in teh posts above... Underdosing and tamp is the reason for teh stuck puck.

    What black plastic thing ;D Remove IT

    Leave a comment:


  • LRF
    replied
    Re: EM6910 stuck puck

    Originally posted by 617465746364110 link=1226019023/0#0 date=1226019023
    I have developed a new problem with the puck sticking to the shower screen of the EM6910. I can get it off by loosening the PF and using the manual button to deliver a one or two second burst of water.

    What are the likely causes for the puck sticking to the shower screen?
    Ive been having the same problem. Tried all sorts of solutions starting with a good clean, then varying the dose and the tamping pressure. Every second puck seems to stick.
    Has anyone tried removing the plastic insert that sits under the filler basket?
    I never had this problem with other machines, just with the Cafe series Sunbeam. Apart from that Im happy with it and its more reliable than my Gaggia.

    Leave a comment:


  • JavaB
    replied
    Re: EM6910 stuck puck

    Originally posted by Thundergod link=1226019023/20#31 date=1228307210
    Yay!!!!!

    So do we conclude that underdosing results in a puck not heavy enough to overcome some kind of suction or other such force at the screen?

    My guess is (based on experience with a La Cimbali 2 group - admittedly a bit different!)

    When water hits the puck it expands.....

    When you updose, there is little or no "head room" for the puck to expend into...
    So the puck becomes compressed and is homogeneous.... like a lump of clay! And stays together rather than sticking to the showerscreen etc... Because it is denser, it wont break up when knocked out.

    With a lower dose the puck has more room to expand into, so doesnt clump together..... it can stick to the showerscreen as it is more like a collection of wet grains of sand..... and will also break up easier.....

    In summary - updosing - a firmer puck which comes out more cleanly (and better tasting espresso as well) - all for the cost of a couple of extra grams of coffee

    Leave a comment:


  • Thundergod
    replied
    Re: EM6910 stuck puck

    Yay!!!!!

    So do we conclude that underdosing results in a puck not heavy enough to overcome some kind of suction or other such force at the screen?

    Leave a comment:


  • peteru
    replied
    Re: EM6910 stuck puck

    My scientific mind is satisfied.   I have a reproducible experiment!  8-)
    • Preheat group handle and portafilter by running 100 ml of water through.
    • Wipe dry portafilter and shower screen.
    • Fill portafilter with freshly ground coffee and tamp with 15kg pressure.
      • A. Fill so that the silver portion of the Sunbeam tamper is about half way above the top of basket.
        (Normal grind)

        B. Fill so that the silver portion of the Sunbeam tamper is completely inside the basket - about 0.5-1.0mm under the top of basket.
        (Slightly finer grind to achieve equivalent extraction to above method.)
    • Pull about a 35-40 ml shot.
    • Wait 20 seconds.
    • Remove PF.

    Method A. will produce a puck that comes out neatly.
    Method B. will produce a puck that will stick to the shower screen and occasionally break up in the PF.

    I performed six experiments in a row, alternating between the two methods.  I had 100% repeatable results with three stuck pucks and three good pucks.

    Leave a comment:


  • Senator
    replied
    Re: EM6910 stuck puck

    good coffee will be with you, always...........

    Leave a comment:


  • peteru
    replied
    Re: EM6910 stuck puck

    These are not the beans you are looking for. Roast along. Nothing to grind here. ;D

    Leave a comment:


  • Coffee2Di4
    replied
    Re: EM6910 stuck puck

    "Help me ObiWanKenobi, youre my only hope..."

    ;D

    Okay, nothing valuable to contribute, I just couldnt help myself... [smiley=lolk.gif]

    Leave a comment:


  • peteru
    replied
    Re: EM6910 stuck puck

    Thundergod,

    Those two seem the most plausible and are probably a (major) contributing factor for me. One thing I would add: When I was having these problems, I was using beans that benefited from a longer than normal extraction.

    I agree that from a simple Newtonian physics point of view, ever-dosing is the most likely explanation, however empirical evidence shows that more complex forces are at work.

    Leave a comment:


  • Thundergod
    replied
    Re: EM6910 stuck puck

    I said previously that a cold basket may be a possibility for me and maybe another factor may have been not removing the PF soon enough.

    Leave a comment:


  • peteru
    replied
    Re: EM6910 stuck puck

    Shadow,

    As I have empirically proven, it is not over-dosing.

    If I fill and tamp to normal level, I dont get a stuck puck. If I fill about 4mm lower than normal, tamp to same pressure AND do the above steps, the puck sticks.

    So, under-dosing is part of the stuck puck phenomena. Perhaps over-extraction is the other half.

    Leave a comment:


  • Thundergod
    replied
    Re: EM6910 stuck puck

    shadow, as I said before, my dosing is consistant.
    Even if I was overdosing, the puck has only stuck 5 or 6 times in the last 2 years.
    I make 10 coffees a week on the 6910.
    You do the math.

    Therfore, overdosing cant be "the only explanation".

    Leave a comment:


  • shadow745
    replied
    Re: EM6910 stuck puck

    IMO any of you that are experiencing this must be over-dosing. Thats the only explanation for the puck to be that close to the screen. Back off a few grams and see how that changes things. Later!

    Leave a comment:


  • peteru
    replied
    Re: EM6910 stuck puck

    Well, I can report that coffee does not seem to obey simple laws of physics.

    Ive been running a number of experiments over the last few days, trying to find a single reason for a stuck puck, but it seems its a combination of a number of factors that causes the issue.

    Heres a way of making a stuck puck (and a disgusting coffee):

    1. Start with cold portafilter/basket.
    2. Use a finer than normal grind.
    3. Underfill the basket (normal tamp pressure should make all of the silver part of the tamper disappear in the basket)
    4. Overextract the coffee to the point where it blonds to white crema and starts turning into stained water.
    5. Wait about a minute before removing the portafilter handle from the head.

    Of course I dont make coffee like that, the point was to make the puck stick - which I accomplished. The lesson learned? Stuck puck is not due to overdosing.

    Leave a comment:


  • sammys
    replied
    Re: EM6910 stuck puck

    I upped the dose for two doubles today. It was a 1g increase for both. Tamped the first a bit soft and ended up with some fissures and a slightly wet puck. Was dryer than the previous ones. Tamped harder on the next one and voila! Dry puck with a reasonable imprint of the shower screen on it.

    Ill start using the scales to get the scientific method going.

    Leave a comment:

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