Interested in trying a quick experiment to help diagnose?
Recently downgraded from a sunbeam conical burr, to a mini-mazzer (it seems).
My mini mazzer + Lelit PL41 + naked portafilter setup gives only two outcomes:
1- Brew head blocks up and only slightly drips
2- Paints my wall, floor, splash back in coffee encouraging thoughts to end my life with a rock.
I have tried all combinations of the following: (all with beans 2 weeks old)
- Fine/coarse grinds
- Tapping/no tapping during dosing and before tamping
- Different volumes of grinds (always with dosing tool)
- Tamping low/high pressure
- Used traditional and naked portafilters
After all experimenting, brought old sunbeam grinder back out, perfect shot achieved (FML).
Any assistance would be greatly appreciated.
Interested in trying a quick experiment to help diagnose?
Sounds to me like maybe distribution related. One thing you might try is getting both grinders adjusted so the shots you produce are blocked and slightly dripping about the same rate based on the same grind weight, purging as you need to.Then back off the grind a bit to coarsen it on both grinders just a bit, ie 1 notch on each, and purge again as needed so the grind output reflects the new grind size. Then using scales, grind a specific grind weight via the sunbeam that is appropriate to your filter basket into a small cup, shake the cup to break up any clumps, dose into the basket, distribute and pull your shot. Try the exact same steps, including dosing and distributing in the same way with the mazzer. Describe each of the shots via this thread
You mention you are tapping, so maybe this won't be of any use - but barista hustle has an interesting piece about distribution. Might be worth a peek.
Wondering if the Mazzer is a manual or an electronic.
If the burrs are new, then single dosing could definitely be causing problems, also if the burrs are old and worn out (unlikely unless its ex cafe been on decaf duty)
Load up the hopper at least half full and grind a decent amount of coffee and see what happens....
Have you tried the layering technique.
Put in 3mm of grinds and lightly tamp (2-3kg), put in 5-6mm and lightly tamp, fill up to required dose amount and lightly tamp. You can add smaller layers if you want. Pull shot.
I believe the theory is you are setting up layers within the coffee to help evenly distributing the ground and water as it flows. This method is too cumbersome in a commercial setting but not cafes don't use naked PF so no one can tell if the shot is channelling anyway.
One experiment has shown that even with a tamping pressure of 300lb, only the first 6mm is compressed leaving the remainder unaffected and susceptable to channelling. Layering addresses this.
First things first. The beans being used. The number one cause of channeling is old beans. At 2 weeks old they could be just now coming into peak flavor/time to use, or they could be ancient beans that are only good for the compost pile.
What coffee are you using? Where did the coffee come from? How and where is it being stored?
Java "By the numbers" phile
Toys! I must have new toys!!!
Aparently the beans were sufficiently fresh to pull a great shot after using a sunbeam grinder but not the mazzer, so the problem as I understand it is to troubleshoot the variance in outcomes from the 2 grinders?
A Mazzer can easily show up problems with marginal beans that a Sumbeam grinder won't.
The original poster has no history here so we have no way of knowing what a "perfect shot" is to them. It could be simply a shot that took a 'reasonable amount of time', again an undefined phrase for us due to the users lack of history here. Many new users think because a shot using supermarket beans took 20-25 seconds it's a 'perfect shot'. Until we get a response from the OP and he gives us some more details we don't know where they fall in the spectrum of experience.
We could have them chasing their tails for days and never solve the problem because the beans were never looked at.
Java "First things first!" phile
Toys! I must have new toys!!!
Interested to see what the OP reports back with, but would be absolutely amazed if the main reason for the OP experiencing bad channelling on a mazzer and not on the Sunbeam was the choice of beans
Owning a sunbeam myself - I wonder whether because of it's poorer, broader particle distribution, it produces enough fines to somehow manage producing a shot that really shouldn't be produced from older beans.. thus being a little more forgiving? But that doesn't necessarily account for the changes in the Mazzer that swings it from choking to channelling. Does the OP know how little the grinder needs to be adjusted to make changes?
Sorry for the delay. I wont be doing this experiment till tomorrow most likely. (final hours of uni for 2015)
in brief reply:
- changed beans, helped a little but channelling still exists. Original beans were 'yahava,' new beans 'big brew' (Perth).
- "perfect shot" was probably a slightly poor choice of words from the sunbeam. the shot was consistent. no spray, flowed at an ideal rate.
- I believe the sunbeam may be a little more forgiving, possibly hiding flaws in the beans OR my dosing, tamping technique. Whereas the more precise mazzer is a little more revealing. The experiment should reveal.
What is the roast date on the beans? What origin/blend are they? How have they been stored?
Java "These things matter!" phile
Toys! I must have new toys!!!
All of a sudden I have begun to have minor channeling problems myself.
Is it correct to believe that channeling is all about the pressure of the water at the showerscreen/puck interface - and therefore the key variables are one or a combination of grind too fine, dose too big and/or tamp too tight?
In my case, the channel always seems to be in the same spot in the basket which suggests a pressure-point. My machine has always tended to build up too much heat requiring long cooling flushes and I wonder if there is maybe a bit of steam pressure in the group that causes a channel to form.
Does the channel move when you rotate the filter-basket, or always at the same 'clock' position?
Mazzer: extraction time not as quick as sunbeam but slightly quicker than ideal, stream ideal, sprays a little more than sunbeam, also slightly bitter but other flavours much more bold
Both prepared the same way. same volume shaken in container, poured directly into basket (tapped basket half way), dressed with flat dosing tool. I never used the dosing tool with the sunbeam in the past. Wondering if this could be a contributor. Four shots is enough for today, will try the same without the dosing tool tomorrow. And slightly finer grind.
The culprit is a region within the puck which provides less resistance to flow.
My quick fix for channelling is to do a nutating tamp before the final tamp - there's a thread somewhere around about it
Here's the thread I was talking about:
Last edited by SniffCoffee; 10th November 2015 at 08:18 PM. Reason: added thread link
Hi Mal, my impression is that the channel is usually at the same "clock" position on the basket (in this case about 8 o'clock)
I have already tried a slightly coarser grind and a lighter tamp and am going to go a notch coarser still.
Mr Jack - yes I agree it would stand to reason that the channel is a region on the puck that provides less resistance - but I can see no reason why there would be less resistance at a particular point (I am pretty anal about the dose/tamp process, tapping the porta-filter whilst loading and stirring the dose with a needle before tamping to break up any lumps (I've never seen any lumps))
Consequently I have tended to wonder about the possibility of higher pressure in the form of steam from the group.
Water seems to come out of the shower screen freely and evenly, suggesting that there is no restriction at the screen.
G'day again mate...
Have you tried changing to a different basket of similar type, eg a Double Ridgeless for another Double Ridgeless?
Got to be something simple mate. Maybe something has changed slightly in your technique that you haven't noticed...
Doubt that it's a jet of Steam (or water for that matter) so you just have to try changing one thing at a time, so that you are certain in your own mind just what is going on...
Have you replaced your shower screen lately? When I picked up a Silvia a while ago, the shower screen seemed to be due for replacement because every time I used the naked group handle it would show one half of the basket extracting before the other.
I tried all kinds of things like tamping un evenly in the opposite direction and moving the basket around clock wise. Got a new shower screen and boom fixed it straight away.
Thanks for the suggestions guys.
Mal - I think you are right about the "something simple" - the machine is very sensitive to minor changes in temp, grind, dose & tamp and I think I have to experiment a bit to see whether it is one of these that has changed. As you say it shouldn't be a little shot of steam as I give it a big flush prior to pour.
As a last resort I will try a different basket and maybe replace the screen.
(Heston - sorry to butt-in to your thread - intention was to let you know you weren't Robinson Crusoe, not to take it over)
Heston, as a next step would suggest making sure your grind distribution is doing the job. If you are interested there are youtube videos that provide a decent overview of techniques like WDT which are imho too slow to do all the time, but useful to be aware of if you arent already to deploy occasionally as part of overall troubleshooting.
Also re your Mazzer, it will help your distribution if you dose the grinds into the basket continually as you grind rather than waiting until the whole portion is ground.
Steam could in theory flash boil (due to pressure falling and lowering the boiling point) and maybe disturb the puck, but not because it's at a higher pressure. Seems highly unlikely though, given the pressure and temperature.
Sat and Sun I tried one notch coarser on the grinder and there was no channeling on the pours.
Single and double baskets always pour differently of course, but the double was a little fast on what was a fairly hard tamp, so next time I will tamp even harder and see if I can slow the flow a little.
I guess I am now into that tricky territory where too hard a tamp builds up water pressure, perhaps predisposing it to channel, and too light produces a tendency to flow too quick with consequent poor extraction.
The quality of both shots were good so I might be within a whisker of the right combination. Who'd have an automatic machine!
I would suggest that you try putting about 3 to 4mm of coffee in the basket and carefully tamp it "hard and level" first (old trick I learnt way back). Then complete the rest of your dose as normal. If no channeling, grind it one notch finer (i.e. your original setting) and do the initial tamp more gently. Hopefully still no channeling. Compare the shots and adjust away from there to your tastebuds content.
PS: semi auto - I would, Fully auto - no way!
I’ve spent some time developing my prep techniques to avoid this channelling issue with improving but wavering results. I found that some bags of beans were more prone than others, all from the same roaster (Yahava Coffee Swan Valley WA). Then I heard someone else having issues with Yahava beans producing wafer thin crema believing their quality has dropped. Change roaster, channelling gone. I now use Bolt Coffee Hazelmere WA and have consistently had no channelling, the extraction is a lot better and the end product much more delicious.
I believe switching to the more accurate Mazzer grinder highlighted the flaw in the beans, where the sunbeam with a more inconsistent grind hid the issue.
Good result! Sounds like your yahava beans may not have been so fresh?... Fiori are now in the swan valley if you want extra variety.