how are you determining that your shots are channeling?
I am having MASSIVE issues with channelling recently... I just had to sink 5 shots, then gave up in frustration. I've tried by VST 18g basket, with doses of 18, 19, 20 and 21g. And I've tried my Synesso 14g basket at doses ranging up to 18g. I've also often wound my K3T to as fine as it will go. Which of course produces clumps. Each shot gets a serious WDT treatment. But nothing seems to help... I'm not sure if it's dose, tamp or grind...
In serious need of help...
how are you determining that your shots are channeling?
Have you cleaned your grinder?
Winding up a K3 as fine as possible does not seem right. Take off the top burr and clean off any grinds and loose/stuck beans from everywhere.
Re-assemble and start again.
Once you done that, weigh the beans on a diet scale for the corresponding weight basket. eg. 18 gms for a 18 gm basket.
Simply grind into the basket.
Tap lightly on the two prongs once.
Tamp, evenly. At this stage, use a moderate to light tamp. More important at this stage to get that even tamping done.After this step, do not even tap on the side of the portafilter or bang it on the bench. This may cause channeling you mentioned. Any loose grounds is then a simple wipe of the lip, and the lugs.
Then look and taste your shots, and then it's a matter of adjusting the grind to achieve 30ml in 30 seconds, My preference is 25 ml in 25 seconds.
I tend to look at my shots and cut off once the blonding stage starts, and that happens at 25 seconds in my set up.
My honest opinion is you are worrying needlessly and I think you are certainly wasting coffee by "sinking" it.
So what if your whatchamacallit is channelling? Its what's in the cup that counts.
Put the silly holey group handle away in the drawer. Work out your grind / dose / tamp to best effect with your beans and equipment, TO GET THE BEST POSSIBLE CUPPA ON PALATE.....and then if when you remove the group handle and find a (god forbid) channel.......turn a blind eye because it wont be relevant.
Your grind / dose/ tamp of course will only work to best effect with the CORRECT DOSE which is, to fill the filter to a point where when you remove it from the group, you can see the imprint of the shower. It doesnt need to be a heavy imprint and its up to you whether you want to "updose" or not (in which case it will be a heavier imprint).
Work backwards from the dose / tamp to get the required grind setting.
After that, relax and enjoy
Hope that helps.
As far as I'm concerned it was the wanton destruction of a good PF.
I dunno. I've got a good use for the naked portafilter. Once I've got the dose/grind right for a particular bean (about 19g for the double), I then place the naked portafilter (with ground coffee) on top of my kitchen scales and weigh (the naked sits flat on the scales..whereas the double/single are a bit wonky). That way SWMBO can make a decent coffee while I'm at work without turning the coffee bench into something out of Willy Wonka. Oh, and i think it stays a touch cleaner as you can rinse both sides of the filter basket without removing it.
a shot in the dark - are you tapping the portafilter on the side with your tamp at all after tamping? i had a similar issue (coffee in the eyeball is never pleasant) found once i stopped tapping channelling all but vanished; assuming everything else is ok ofc!
Alright. To reply to all of the above:
Yelta- The shots aren't great. They are better than most coffees I've been getting out (dodgy cafe's which are convenient more than anything else). But I know the machine can do better, I spent months getting great shots from this combo. I want that back.
Fresh_Coffee- Little bits of channeling sure, but it is affecting the taste of the shot. So i want to fix that...
Troyboy- No, not tapping.
I will give the grinder a good clean. Try a 18g dose in my vst and go from there.
Will let you know how it goes!
From my limited experience with causes of channelling, I found that changing beans had a big impact. As did visiting Jetblack and getting a tip on the dose size that suited my machine, they were very helpful.
I had been using freshly roasted beans from a very popular Sydney CBD coffee shop and after sticking to the recommended dose and changing beans, I have not had any where near the ongoing channelling problem I used to have.
It wont, if you sort out the required grind / DOSE / tamp for the beans you are currently using to suit the equipment you are using. Get that (grind / DOSE / tamp) sorted properly, and I doubt any chanelling that occurs after that point will affect the taste of the shot.....it will be no more than a "....yup, there's a channel, but I cant say it's affected the great coffee I've just made and cupped...".
Considering the importance of understanding the importance of the DOSE to properly working out the rest of the set up & technique, we should be saying "DOSE / tamp / grind / rate of pour / character in cup" in that order, instead of the simplified grind / dose / tamp.
Honestly, cleaning the grinder and weighing an 18 gram dose into whatever filter is in use are not going to do anything. It doesnt matter what size or type filter is used, the golden rule is to fill the filter to the correct level (dose) FOR THAT FILTER for that design of group on that machine for that grind, for those beans. The only way I know of to do that is to do it volumetrically....the weight is irrelevant, and will change dependent on type of beans / grind setting / intensity of settle and tamp / density in the puk. You could weigh out 18 grams, into a nominal 18 gram filter, for any particular grind, and it still may not be the right dose, and the character of the coffee may not be all that good, irrespective of whether it channelled or not.
Get this right, and your problem will become *insignificant* whether you see an occasional channel or not..
Hope that helps.
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Last edited by Fresh_Coffee; 17th July 2012 at 09:24 PM.
Thanks again to everyone for their helpful responses and for reaffirming my faith in myself that I do actually know what I am doing. The grinder got a good clean this morning. Filter basket got a rice test and a 5c test. Dosed to 16g in the 14g synesso and away we went. Resulting shot did still channel a little. But as Attilio said, it doesn't affect the taste of the shot. Which is absolutely beautiful. Thanks everyone!
I remember a while back when I was struggling with channeling. My solution was to stop doing extra crap at the dose and distribution stage. If I was able to dose the basket in a reasonably clean and 'centred' way, straight from the grinder, then forget levelling, sweeping, WDT, or any of that stuff. just stomp it with the tamper and brew. Don't even 'twist' or 'polish' the top of the puck with your tamper. Every thing you do to that bed of grinds is just going to screw it up even more.
Often overlooked or not considered is how rough you can be with the dosed portafilter when locking it in to your machine, if you are clanging and banging that PF in to the group head, of course it's going to also destroy that bed of grinds before brewing. Be very gentle with it after dose/tamp
Over-complicating the dose/distribution/tamp process can easily result in issues in the cup. Keep it simple!
I get the impression that some machines are more 'dose sensitive' than others.
My Perfetta is very dose sensitive and if I under or overdose I can guarantee that the result will be inferior.
If I get channelling it will generally be with an overdose. Underdosing produces a slightly thinner faster pour.
Sometimes I have two Demis under the double basket PF and only one spout will produce. I just shut off the pour and start again and immediately the other spout will deliver.
I take a lot of care to have precisely the right dose in the PF to get the best pour.
I used this test but used couscous instead- the particles are finer and you get a more accurate result.
It's great to know the level where your coffee is just clear of the shower screen
Also I agree with JamesM - i just time the shot from my grinder and do a single tamp. no fancy tapping or levelling. ( but i do a single twist and polish- beacuse i like that bit) Occassionally adjust the time if necessary.
I'm no expert mind you but getting consistent results....
Just my 5cents worth, maybe try distributing the coffee evenly across the basket with your index finger or back of a knife. This often leads to an even extraction.