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Thread: EM6910 stuck puck

  1. #1
    Member peteru's Avatar
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    EM6910 stuck puck

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    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?

  2. #2
    Sleep is overrated Thundergod's Avatar
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    Re: EM6910 stuck puck

    It happened to me too yesterday.
    Maybe its the weather.
    Ill be looking forward to the answer as well.

  3. #3
    Senior Member Dennis's Avatar
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    Re: EM6910 stuck puck

    Near perfect dispersion, smooth, level tamp, finer grind, all make a nice seal on the screen.

    Thats just my theory. :-/ Then again, it happens more with some machines than others.

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    Re: EM6910 stuck puck

    I changed many variables over time as I try to get closer and closer to the perfect shot on demand. Some of the changes were to my dispersion and tamping technique. I now run a thin piece of metal through the coffee and tap the PF lightly to get as even distribution of coffee as possible before tamping. The tamp is now just a single steady push down, instead of several pokes followed by a handstand. :D The final polish is with almost no pressure - just the weight of my hand. I get better extractions now. However, I had the stuck puck problem even before I adopted the above technique.

    Would under/over dosing result in a stuck puck? If so, what is a good way to determine the correct dosing?

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    Re: EM6910 stuck puck

    Quote Originally Posted by Dennis link=1226019023/0#2 date=1226020239
    Near perfect dispersion, smooth, level tamp, finer grind, all make a nice seal on the screen.

    Thats just my theory. *:-/ *Then again, it happens more with some machines than others.
    I get this problem too. Does that mean im doing something right? ::)

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    Re: EM6910 stuck puck

    It used to happen to me when the puck was a tad wet, not soppy like you can get when not dosed enough, but almost like it was borderline slightly under and may not have expanded enough in the basket to be held in firmly with the pressurised water.


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    Re: EM6910 stuck puck

    Mine did it when it was brand new. We had to buy ground beans from a big cafe chain in Perth because we were waiting on Rocky coming in to the shop. Since then, I get my beans from a place that sends them the day they roast them, so they are 1 day old (usually), and it has never happened again.
    I dont know how fresh your beans are, but that could be something.

  8. #8
    Senior Member Stan's Avatar
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    Re: EM6910 stuck puck

    I get it as well from time to time but I thought it was the grind as when I adjust the grind a little courser it doesnt stick. But then again it only happens occasionally (except if you leave the PF in when you steam the milk) then it sticks every time. ::)

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    Sleep is overrated Thundergod's Avatar
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    Re: EM6910 stuck puck

    I always leave the pf in until after Ive poured the milk so I disagree that its a cause.

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    Re: EM6910 stuck puck

    Ive been using the 6900/6910 for more than 2 years and have never had this occur.

    I feel inadequate now :-(

  11. #11
    Senior Member Stan's Avatar
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    Re: EM6910 stuck puck

    Well all I can put it down to then is the relative humidity or perhaps the water quality or maybe the tamping or the grind or the time of day or was I standing to the right or left or maybe ;D ;D ;D ;D

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    Re: EM6910 stuck puck

    It seems that using a little bit more coffee is helping things. I have not been able to definitively conclude that the dosing is the only variable making a difference, since increasing the dose also requires a slightly coarser grind.

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    Re: EM6910 stuck puck

    Hi there,

    Ive managed to get sticky pucks on several occasions using a EM6910/M4D Micrometric combination. Ive found that grinding a little finer fixes it.

    Thinking it through has led me to believe the problem is caused by the grind being set between just right and course enough for the granules to not stick together. Ive started calling this the M&S grind (moist & sticky).

    Im keen to hear if grinding finer fixes the problem for you as well.


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    Re: EM6910 stuck puck

    Been playing around with it a bit more and im starting to believe its related to dosing as well. I googled wet puck and found other forums reporting the wet puck being caused by underdosing.

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    Re: EM6910 stuck puck

    It seems I have two solutions to help with this:

    1. More coffee, coarser grind, heavier tamp.

    2. More coffee, same grind, lighter tamp.

    It still happens every now and then, so I still dont have a clear idea of what the issue is. I am a little concerned about overdosing though, in light of the risk of damaging the collar.

  16. #16
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    Re: EM6910 stuck puck

    Im confident my grind, dosing etc is consistant so disagree that more or less coffee is the answer.


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    A_M
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    Re: EM6910 stuck puck

    Quote Originally Posted by Honest Gaza link=1226019023/0#9 date=1226048564
    Ive been using the 6900/6910 for more than 2 years and have never had this occur.

    I feel inadequate now :-(
    Dont feel inadequate.. *It is no ideal outcome *;D

    1: Stuck Vs Wet are different and not to be confused.

    I have had *one or two stuck at times and it is due to a combination of Grind,Tamp and UP/Overdosing *:o

    Now I know some will jump at that...... *BUT the pure physics and evidence proves it *8-)

    A: To be stuck to the shower screen; it must have been up there to start with AND OR has expanded with the infusion; such that the grinds are in physical contact with the shower screen.

    If not, *then many scientists would like to know how you can suspend a puck in mid air *::) and defeat gravity. *Unless your in *space... *::)

    B: When you unlock the PF; *if you also have the right consistency and dryness/wetness *then there is enough bonding throughout the puck and the interface with the shower screen (Unless your defeating gravity) to hold it to the shower screen and ALSO break it from the smooth walls of the PF.

    Thus while I can not comment on your beans, grind, tamp and any other variables: *it still stands to reason, that to become stuck to the shower screen.

    Then it must be in contact AND with some level of force; be it overdosing and or expansion (beans / grind etc). *8-) * I do not thing it is any one thing but more a combination of the product and significant contact with the shower screen.

    Note: I have had my wife do it, where she has left the system in place and had to rush out. *Only to come back a few hrs later, go to make a coffee and can not put a new filled PF in. Only to find the old puck was still in place... Then again that is her and not me *;D

    Feel free to explain it any other way... *

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    Re: EM6910 stuck puck

    AngerManagements theories make perfect sense - there has to be enough coffee in the portafilter to make good seal with the showerscreen. Unless, somehow, high pressure physics and the fluid dynamics can cause the coffee to "float" to the top - which is not very likely.

    If I also apply my scientific hat and start postulating theories, then I have another plausible explanation:

    Cold filter basket?
    When you start with a cold filter basket, the coffee makes a tight contact with the walls. As the basket warms up, the diameter increases and the adhesion of the puck to the side walls becomes weaker than the adhesion to the shower screen. At the end of the pull, the puck ends up stuck to the shower screen and loose in the filter.

    The temperature of the filter basket is not one of the variables that I paid too much attention to in the past. However, thinking back to when I had the most frequent troubles with a stuck puck, I was sometimes dosing the filter basket on its own, while the portafilter handle was pre-heating in the coffee machine. Ill run a couple of tests where I will only vary the temperature of the filter basket to see if that is the culprit.

  19. #19
    Sleep is overrated Thundergod's Avatar
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    Re: EM6910 stuck puck

    Cold filter basket might be an answer.

    I warm the cup and the empty PF with hot water but the basket is only at room temp or at best the temp of my shirt pocket before its loaded into the PF just before I add the grinds.

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    Re: EM6910 stuck puck

    I did one test run. Cold basket and portafilter vs. warm/hot basket and portafilter. Neither of them resulted in a stuck puck.

    Cold basket gave me what I considered a nicer extraction with richer crema, but the puck was a bit "patchy" and inconsistent at the end. It sort of broke up in segments/layers. Blonding onset was gradual.

    Warm basket was a bit drippy at the start and then extracted OK. The puck came out nicely as one unit and cleanly too. The blonding stage had a well defined and sudden onset.

    Both were dosed to the same level, at the same grind and tamped on scales to 15kg.

    Inconclusive, so I will repeat the experiment a few more times over the next few days.

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    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. ;)

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    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.

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    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!

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    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".

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    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.

  26. #26
    Sleep is overrated Thundergod's Avatar
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    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.

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    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.

  28. #28
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    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]

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    Re: EM6910 stuck puck

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

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    Re: EM6910 stuck puck

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

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    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.

  32. #32
    Sleep is overrated Thundergod's Avatar
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    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?

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    Re: EM6910 stuck puck

    Quote 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 :)

  34. #34
    LRF
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    Re: EM6910 stuck puck

    Quote 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.

  35. #35
    A_M
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    Re: EM6910 stuck puck

    Quote Originally Posted by 57495D1B0 link=1226019023/33#33 date=1291169381
    Quote 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 ;)



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