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Thread: EM6910: Replaced collar & seal, needs very firm pressure on handle to get a good seal

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    EM6910: Replaced collar & seal, needs very firm pressure on handle to get a good seal

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    My EM6910 has recently had a new collar and seal fitted, and I'm not sure everything is quite right. If I use a relatively high pressure shot (needle at the upper end of the recommended range, or even a bit higher than that), I need to apply very firm pressure on the group handle in order to get a good seal. When it leaks, it always leaks from the same place - the front left hand side of the group head. I tried my group handle and filter basket in a friend's EM6910, and it works much better - I only need to apply a small force on the handle, for a similarly high pressure.

    After the new collar & seal were fitted, I did notice that the handle doesn't move as far to the right as it used to (which I know is good/expected), but the resistance seems to build up more rapidly than the other machine - the other one feels very smooth.

    I rang around a few repairers, and two of them said the same thing - that it is normal for a new collar & seal to feel tighter, and it will bed in. The only problem with this is that I tried my friend's machine when it was brand new, and it still felt smoother and easier to get a good seal. (I bought my machine used)

    Any advice much appreciated - thanks.

    Greg.

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    2 things I can think of... 1 is the ramps on the collar are different now - IIRC there are 2 different collars available, 1 from an older 6910 version - if your friend's is new and yours is the older model (not necessarily indicated by purchase date) you could have a different experience. The other is the lugs on your PF might be worn to suit your old collar and now fit differently on your new one - for the difference with your friend's see reason 1.

    The leak I have found tends to come from over-dosing. The manual is, IMO, wrong. I get best results dosing about 4mm down in the basket, even on the SB ones. Trying dropping your dose a little and see if the leak goes away.

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    Thanks. Yes, the technician that repaired my machine advised me to drop my dose, but I still have the same problem. I am currently using 15g in the double basket. I do not see any of the silver lining of the tamp showing when I tamp. I am very confident that the grinds are not touching the shower screen and preventing the tightening of the portafilter.

    Greg.

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    I have a 6910 [nearly 5 years old] and I tamp so that only 50% of the silver lining shows, I use the single basket - I regularly enjoy the result!

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    Quote Originally Posted by Skip View Post
    the technician that repaired my machine advised me to drop my dose
    I had to get mine fixed for a separate issue (leaking from under the machine and lack of steam pressure) and the technician told me that I shouldn't use single floor baskets as it wasn't worth it and real baristas in cafes always use double floor baskets... This has made me 'reevaluate' some of my technician sourced advice...

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    Quote Originally Posted by fLame View Post
    I had to get mine fixed for a separate issue (leaking from under the machine and lack of steam pressure) and the technician told me that I shouldn't use single floor baskets as it wasn't worth it and real baristas in cafes always use double floor baskets... This has made me 'reevaluate' some of my technician sourced advice...
    A friend of mine (a different friend - got lots of 'em ;^) told me that a barista told him the same thing - not to use singles. I was very skeptical of this at first, but after perusing the forums for a while, I got the impression that there may be some credence to this - apparently it is harder to pull a good single, due to the tolerances being tighter - there are less grinds, which makes it more difficult to dose and tamp accurately. I even saw a comment to this affect in a video on that Seattle Coffee Gear site - Gale's assistant made a comment like "this will be the first time I've seen Gale attempt a single". However, even if it's true, I wonder whether it applies to a 7g shot. I think the Sunbeam single basket takes more than 7g.

    Not sure what I'm going to do next re my problem - not looking forward to asking my technician about the possibility of multiple collar profiles.

    Greg.

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    Hello there,
    Personally I'd check to see that your group handle locking lugs are contacting evenly on both collar cam surfaces - maybe mark some ink (from a permanent marker) on the underside of the group handle lugs. Cupping the group handle I would press it hard up against the surface of the group seal (using the seal surface as the square point of reference) and gently turn the handle until it just starts to engage the lugs. Maintaining upward pressure, carefully remove the group handle and examine the surface of the lugs. If theyre engaging unevenly then your're putting uneven pressure against the main seal. If thats going on your new collar's lifespan will suffer.

    Personally if I were installing a new collar I'd run a vernier on the collar / group handle before I started - making sure surfaces were true to eachother before starting, but that said if only one lug is engaging when the handle locks up against the main seal then the way its going to 'wear in' is my crushing the surface of the collar. Personally, I wouldn't put up with that.
    Last edited by mspw; 24th March 2014 at 11:08 PM.

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    MSPW: Thankyou! When I rotate it until it just gently engages (as far as I can without using the handle), I can't see any removal of ink from either lug. However, if I then use the handle to tighten further, there is removal of ink from one lug only, AND, the lug that doesn't have any removal of ink ends up (after rotation) at about the point where it always leaks from.

    Note that the technician said to give it another month to bed in, and in a couple of weeks I'll be taking it back to him. I was going to go along with that, but armed with this new knowledge, I'll probably take it straight back ASAP.

    So, what do you think the problem is? A badly aligned collar? Are you saying that the collar needs to be aligned carefully when it is installed? Or could it simply be a bad collar?

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    Hi there and sorry about the lateness of this reply. To me, if you're getting uneven lug engagement then off the top of my head you're probably not limited to - an uneven or unclean mounting surface the collar was mounted to, a distorted collar, unequally torqued screws (or a stripped screw somewhere in the equasion), a burr on one of the mounting points of the collar or possibly installed to and uncleaned surface? Equipment mishandled during the install is possible but that is a lot of 'whatifs'.

    One could ascert the repairer may have skipped some loving care along the way and assumed she'd be right. He may not realise how much of a problem you're experiencing. The assumption might be both lugs are locking but with a little uneven contact pressure around the seal. If you follow the repairers advice and things start working the way they should then great. Still might be reassurring for you to get that advice in writing somewhere, maybe via an email discussion because if it does finally 'bed in' either the main seal is going to have to give in or the collar does. If the seal manages to permanently distort enough to solve your problem then the same issues may reoccurr when it's time to replace that seal. If not the seal then the collar has to be the one that gives.

    Just as an exercise, might be worth removing the showerscreen and seal and just make sure there isn't dirt or debris up under where the seal sits.
    Last edited by mspw; 30th March 2014 at 04:11 PM.

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    Sorry for my late reply too.

    I can't be sure now whether the engagement is uneven, because I can see some removal of ink on the suspect lug as well, but the width of the wear path is less than the other one. This doesn't necessarily mean that the force applied to that lug is any less than the other one - it could be the same force, but over a smaller area. I've decided to just do what the technician suggested - wait a bit longer and then take it back to him if it still has the same problem. (it'll be about another week now) In the meantime, I'm using a lower pressure (requiring a lower handle tortion) than I would ideally like to, to reduce collar wear. This probably isn't what the technician wanted me to do, but too bad. ;^) My shot times are around 20 seconds for a double.

    Btw, can anyone point me to a table that lists average shot times for different basket diameters, if the quantity of grinds is held constant?

    Greg.

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    I took it back to the repair technician. It didn't leak for him, but he tightened it more than I had been - it was about level with the little arrow to the right of the "secure firmly" label on the group head. I told him how a friend's machine only needs to be tightened gently, such that the handle is perpendicular (even if the machine is choked with a very high pressure), but he said every machine is different, and they all have their idiosyncrasies. The funny thing is, I'm sure he had on an earlier occasion told me to just tighten it gently, so that the collar doesn't wear prematurely! (I wish I had remembered this - I would have taken him to task).

    Anyway, I'm finding that for a 25 second double shot, the pressure needle is at the upper end of the recommended range, and I don't have to tighten it TOO tightly, so I think I'm pretty ok for now. (the handle is a bit to the left of that aforementioned arrow). I realise that the shot times are just a guide and I should also look at colour and determine what I like in the flavour etc - I'm a beginner though and want to start somewhere in the recommended range.

    I haven't inspected for debris under the seal & shower screen yet. Is it ok to turn the machine upside down, or should I get a mirror?

    Greg.

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    No probs with upside down but you only need to lay it on its back. Use the handle of a teaspoon (rounded) to remove the blue seal - anything sharp may damage it. The seal should be pliable and squash under mild pressure. Note which way it is and how the two screens fit in before you remove it.

    ebay has cardboard spacers that go in above the blue seal if the position of the handle worries you - moves it back towards centre position. The tech is full of it; properly adjusted the handle SHOULD be like your friend's one. But he's right in that it doesn't really matter provided a good seal is made.

    Another possibility he might have mentioned is the lugs can get worn, probably from people tightening it too much over long periods. That would mean replacing the collar (or perhaps the PF if that's where the wear is) which is a bigger job but again there are Google/ebay places you can get replacements.

    Another good way to help with the process is to get a naked PF - with the bottom cut out of a handle you can see how the coffee comes out. It's an excellent tool for working out some of the things that go wrong with tamping etc.

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    Problem solved - it WAS worn lugs on the porta filter! Whilst I had already tried my porta filter in my friend's machine, I had not tried my friend's porta filter in my machine. I have now done that, and it feels appreciably tighter when I turn it, and for a shot with the needle in the centre of the recommended range, I can in fact have the handle slightly to the LEFT of centre! There is no way I can do that with my worn porta filter.

    Also, I tried the worn one in my friend's machine again, and there is a TINY bit of leakage from the same spot where it leaks from mine. Just a tiny drop, but it's there.

    I'm ecstatic - problems like this bug the hell out of me!!

    Thanks again everyone for all your help.

    Off to source a porta filter. I probably won't get a naked one - my shots seem to be coming out well and consistently so I don't see much point. I DO want a single-pour spout though.

    Greg.

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    Quote Originally Posted by Skip View Post
    Thanks again everyone for all your help.

    Off to source a porta filter. I probably won't get a naked one - my shots seem to be coming out well and consistently so I don't see much point.

    Greg.
    While you sourcing a new P/F, you might get a second one, I got mine from a repair shop, for nothing!

    Cut the bottom out of it, to create a Naked P/F.

    Worth it in my view, to look and see what is going on, I use it all the time now, with a 7gm VST.

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    I'll ring around the repair shops - thanks for the tip!

    Just did my first real shot, with the pressure higher - the needle was half way between the top of the recommended range and the red zone, and yet I was still able to have the handle to the LEFT of centre, and more importantly perhaps, I didn't need to apply as much force. There is a world of difference. I don't know why I didn't notice the difference in behaviour when I tried my portafilter in my friend's machine, the first time.

    Now that this silly problem has been solved, I can start experimenting with the dosage, which we discussed a bit earlier. I see that the guy on the Sunbeam video is putting in a lot more grinds than I am! This morning I used 17g, firmly tamped, and yet a $2 coin (which is quite thick) only left an extremely shallow impression in the puck - I think I can go higher still.

    Greg.

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    When I first started making good coffee, I was dosing as high as I could get away with. I figured the more grounds in there, the more flavour I'd get in the cup.

    While that may be so, once I got the VST baskets I found I can get a very high level of flavour with much less coffee. I grind finer for the VST's by 2 or 3 notches on the EM0480 (depends on the beans) and the needle sits at the top of the upper 'good' zone and I get my 60ml in circa 25 - 30secs. I'm dosing about 15g in the 15g VST but the level is about 5mm down from the top.

    I also found progressive tamping (in both VST and SB baskets) provides more flavour from the shot. There are a couple of discussions on here about what happens with even 'hulk-smash' levels of tamping and what I know of grain physics tells me the idea that regular tamping as the basket fills is a better way to get an even distribution of pressure through the puck, so ALL the coffee gets extracted properly, not just the top half.

    For anyone interested, grains are a rather unusual state - the physics that governs how the pressure is distributed in the basket is the same as that which has all sand dunes with the same incline angle. i.e. there's considerable sideways distribution of the force applied.

    I've tried it a couple of times after seeing the back and forth on here and each time I come away convinced it is better to tamp in small doses. It might not be economic in a busy café but for home use where you can spend the extra few seconds, it gives a better cup.

    And I would second the suggestion re naked. It's a great tool to see what is happening AND to improve tamping - the flat base gets rid of any angle or wobble when you tamp.

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    Thanks Journeyman. For the intermediate tamps, do you tamp gently? I saw mention of an automated tamper that tamps multiple times, but it only tamps very gently, which is obviously because it is only having to compact a much smaller quantity of grinds each time it tamps. Yes - I will definitely try this method - it makes a lot of sense to me.

    Actually the SB barista on the DVD does two intermediate tamps too, although they appear to be very gentle.

    I also read somewhere that a "hulk tamp" doesn't really make much difference over a normal tamp - presumably a plot of compaction vs tamp pressure would be some kind of logarithmic curve, with diminishing returns?

    Greg.

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    Pretty much so - the grains distribute the pressure as much sideways as down so the compaction drops off rapidly with depth, probably logarithmically. It's why dunes 'fall over' when they get to a specific angle - think it's 35º but it was a long time ago so that might not be the right figure.

    Yes, light tamps - mine are somewhere between 2 & 3kg as per kitchen scale. If my pour is too fast I drop a notch on the grinder and tamp even lighter till I find the sweet spot.

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    Thanks again Journeyman.

    Got my new portafilter, and it's behaving the same as my friend's one - I just did a shot that was nudging the red zone, with the handle a good 10 degrees or so to the left of centre, with no leaking for just a snug twist - not forceful. Happy days.

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    I still think the force required to get a good seal is more than the other machine I've been testing with, and I'm afraid that I suspect I still haven't really gotten to the bottom of the problem. I've definitely moved the "good seal" position of the handle well over to the left, but I'm not so sure now whether I've reduced the torque. I suspect I'd need to look into the things that MSPW suggested earlier to really sort it out. Not sure whether I'll go any further with it for now though. (although I will at least have a look under the seal - that's trivial to do)

    I accept that if I had simply shimmied the seal & screens up a bit with cardboard I may have achieved the same result, without the cost of the new portafilter. (but I just don't like the sound of that idea much)

    Greg.

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    The cardboard shim I first made was only ever a temporary solution to stop leaks until I got the collar replaced just before the warranty ran out.

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    Check the basket

    Skip! I may have something for you to check.

    I recently went through the same process. Replaced seal. Replaced collar. Bashed head against wall. Thought maybe I'd seated the collar badly, so did it again.

    And then something caught my eye.

    The filter basket itself.

    See this image. (apologies if you're not supposed to post images but I couldn't find any such rules).




    https://lh6.googleusercontent.com/-N...511_114446.jpg

    I wedged a small screwdriver to exaggerate the problem so it could be easily seen.

    Anyway, my issue is FIXED. Hopefully this may assist with yours.

    Cheers,
    Glenn.

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    Thanks Glenn, but I don't think that's my problem - I've tried more than one filter basket.

    I've started lubricating the lugs and FB rim (using olive oil spray, just because I already had some), and that's helping. The new collar seems to have a bit of a "notch", and I think this notch is causing the initial resistance - not so much the friction of the seal against the rim. Lubrication helps me to get past this notch without having to apply excessive force. (maybe it will go away in time, as it wears). Even with lubrication, though, I am still able to leave the handle to the left of centre, using the new PF.

    I am still of the strong opinion that both the collar and PF lugs were worn.

    I'm happy with the way things are for the time being.

    Greg.

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    Pleased I found this thread! Replaced my collar and seal last year and was disappointed I was still getting a leak...

    Have been tightening quite hard to compensate (not always successfully) - originally suspected it may have been the basket or PF, guess this gives me some ways to test it...

    Thanks!

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    Good luck Footleg - I'll be very interested to hear how you go. Just enjoying an excellent cuppa right now - I'm really happy with how my coffee making is going. I'm getting a very pleasant "liquid powder" sensation in my mouth too.

    Greg.



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