Help with channeling - Page 4

Beginner and pro baristas share tips and tricks for making espresso.
cai42
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#31: Post by cai42 »

Greetings,

Do you like the taste of the shots you're making? If yes, get a spouted portafilter and you won't see what's going on.

Cliff

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crazy4espresso
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#32: Post by crazy4espresso »

Great post by Anvan. I'm curious about the pre-infusion times as well. Try experimenting with a longer time and see what happens.
"I would rather suffer with coffee than be senseless." — Napoleon Bonaparte
LMWDP #427

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MVendi81
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#33: Post by MVendi81 »

I have the same grinder, and use almost the same exact technique (sawed-off yogurt cup, WDT). In my experience, removal of the yogurt cup after stirring causes slight voids around the edge of the basket--you can see this from the ground coffee stuck to the sides of the plastic cup. These areas are less dense, which might explain the problems you're having.

What I do is, after I take the yogurt cup out of the basket, gently give another stir with the needle only about an eighth of an inch under the surface of the coffee, focusing mostly along the edge to even things out. It sounds ridiculous, but it works!

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shawndo
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#34: Post by shawndo »

I have been having tons of channeling problems, as is demonstrated in this thread
What can cause variable puck expansion

I think I've mostly solved them. First was absolutely zero, none, no tapping the basket or PF to settle the grounds. Some people seem to be able to do this, but it doesn't work for me. Second, a euro-curve convex tamper (deeper curve than the american convex) It is generally against the normal forum wisdom (and VST recommendations) to use this with a VST basket, but I hope to verify my results with some refractometer results in the next few weeks. The pulls sure are pretty and tasty!
Darmok and Jalad at Tanagra

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Peppersass
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#35: Post by Peppersass »

Earlier in the thread, you mentioned that the spring in the PF is a PITA. Did you take it out or are you using a ridgeless basket now? If you're still using a ridged basket with the spring, odds are that you're disturbing the puck when you snap the basket into the PF.

I agree that the yogurt cup or dosing funnel leaves a void around the edge. Try NEWS sweeping or Sockfleths to fill that void and level the top of the puck.

I didn't see a scale being used in the photo. Are you setting the Mini E's timer and expecting that it gives you a perfectly calibrated dose? I wouldn't, at least not until you solve the extraction problems. Use the scale to get the exact same dose every time.

VST recommends dosing within +/- 1g of the rated basket capacity. John gave you good advice about lowering the dose, but I wouldn't dose 16g into an 18g VST basket. I'd use the 15g basket for that dose.

If you have one, try a non-VST basket with an appropriate dose. Let's see if the type of basket makes a difference.

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williamsavona (original poster)
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#36: Post by williamsavona (original poster) »

Thanks again to everyone for being so helpful! You guys are seriously the thing that is making this continue to be so much fun.

Special thanks to Anvan for the epic post. It's really helpful! I will definitely be trying out your suggested experiment this weekend but here are some initial thoughts and a quick video update (spoiler: things are improving)
Anvan wrote: Others have written - and I've confirmed to my satisfaction from tests I've done myself - that pre-infusion works well to cure at least some donut or halo problems. Sometimes the shot-to-shot differences are dramatic and the donuts simply disappear altogether. The reasoning from here is that PI expands the coffee and tightens the puck throughout, evening up the pack's density and undoing most of the random and non-random inconsistencies that cause dead spots anywhere, including those in the center. If you're currently using a short pre-infusion but still have problems, try a "Magnum PI" for 15 seconds, just to see what happens.
I suspect this might be really helpful to temper my distribution issues however until I get my machine plumbed in (having trouble with BSP to NPT conversion fittings at the moment) pre-infusion is not really an option. While you can get a tiny amount of pre-infusion from my machine when running off the water resevior it isn't something I could really reliably work into a routine at this point. Once I do get the machine hooked up to the water line with a pressure regulator I'll be able to test how pre-infusion affects the pour.
Anvan wrote: Basket bottoms are frequently rounded - even if they're flat when new, the high pressures and constant use will bow the flat surface. This affects thin baskets more quickly, but even the best or heaviest baskets are not immune from 9 bars hitting them again and again. Just that slight extra puck thickness in the middle can be enough to divert the flow elsewhere.
I am very new to this world so I have nothing to compare them to, but I have to say I am surprised by just how round the bottom of my baskets are (these are from the manf. of the machine).
Anvan wrote: You may likely have more problems with too-fresh beans than stale coffee. This affects channeling in general (and especially affects large doses) since the heavier out-gassing during brewing can break up a puck's integrity. It may also disproportionately cause edge channeling if the brew water quickly causes a lot of fizzing at the basket-wall enough that the fissure never can repair itself. Stale coffee has its own problems, but at least in my experience, it isn't usually the cause of donut-pour problems.
I did not know this and I am so glad I know now! This may be part of my problem. Because I am just starting out, and flying through beans, I haven't been able to keep them longer than 6 or 7 days post-roast. The last video I posted was done using beans that were 6 days post-roast. Over the last few days I have notice some improvement to my pours. Maybe I need to wait longer before jumping into a new bag (it's just hard not to get excited!)
Anvan wrote:While clumping might prevent some free migration of local fines at some stage of the prep - and could possibly therefore cause random unevenness of flow (if the tamp doesn't crush them into submission and the fines distribution ends up affecting the pour) clumping and persistent donut pours are not going to be related.
This makes perfect sense to me and is why I am haven't been focusing too much attention on destroying every little tiny clump during WDT. To my eye the clumps are pretty minimal in both quantity and size.
Peppersass wrote:I didn't see a scale being used in the photo. Are you setting the Mini E's timer and expecting that it gives you a perfectly calibrated dose? I wouldn't, at least not until you solve the extraction problems. Use the scale to get the exact same dose every time.
I am using a scale however I am about ready to throw it out my kitchen window out of frustration! It is not reliable and I find it to be inconsistant by as much as a couple grams. It's also slow to respond and auto-powers off far too soon. I ordered an American Weigh Scales SC-2KG-A earlier this week and it should arrive today or tomorrow.
Peppersass wrote:VST recommends dosing within +/- 1g of the rated basket capacity. John gave you good advice about lowering the dose, but I wouldn't dose 16g into an 18g VST basket. I'd use the 15g basket for that dose.
I am actually not using VST baskets. I am using the stock manf. supplied double basket for this. I've heard a lot about them but I am wary of throwing another variable into the mix at this point.


SOME IMPROVEMENT:
I am not sure if it is the maturity of the beans (they are 8 days post-roast) or some minor improvement to the distribution technique I've been using (only change I've made is to add a quick gentle WDT after pulling out the funnel as suggested by MVendi81) but there does seem to be some improvement to the last few shots I've pulled. Here's the latest video from about an hour ago:

jontyc
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#37: Post by jontyc »

Anvan wrote:
  • We should differentiate between serious "edge channeling" - where at least some of brew water flows rapidly along the sides - and a "halo" where most of the brew exits the basket away from the center. Yes, this is in some ways a matter of degree, but we have to recognize that there will always be some tendency for faster edge flow. The trick is to minimize that difference.
  • Maybe at the start, the flow will first appear around the edges, but in a good basket prep, it will be temporary and self-healing. That early flow expands the coffee grains in the cake at the outside - where it naturally starts - creating a tighter matrix and incenting the flow to move progressively toward the center - until the shot becomes essentially even across the basket bottom.
This halo effect has been plaguing me (although I suspect it's no big a deal, just OCD), but noticed all other vids from the same machine (mypressi) did the same (like below at 0:35). That seemed to rule out distribution, so then concluded that was because its diffuser throws at the perimeter of the showerscreen. Until, that is, I noticed the showerscreen grate evened things out to give a nicely diffused shower.
So your explanation here makes a lot of sense. I still see some vids with pours starting from the center, like here:
Doser slightly compacting at the perimeter, maybe?
Anvan wrote:
  • If a convex tamper seems logical and it works for you, great. But don't bet on it. A convex tamper is just as likely to pack the coffee harder in the middle and make the donut problem worse instead of compensating for a bowed basket bottom.
What I was thinking could work, but I don't have a convex tamper to test it, is to do a light tamp with a convex to spread the grinds slightly towards the perimeter, then a final tamp with a flat?

genovese
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#38: Post by genovese »

williamsavona wrote:having trouble with BSP to NPT conversion fittings at the moment
I like Grainger for this; last time, I ordered online and they had my adapter in my mailbox in 3 days. I used THIS ONE, but they have other size/gender configurations. You could fudge it with NPT and a lot of teflon tape, I know, but it's just as easy to do it right.

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MVendi81
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#39: Post by MVendi81 »

Looks better William, keep at it! It still looks like you have some unevenness toward the front-left edge of the basket, but definitely an improvement. Maybe try stirring a little harder on your first pass....I know some days the Mini E clumps pretty badly and I really have to give the grounds a beating. I guess it all depends on how humid my kitchen is on any given day.

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Peppersass
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#40: Post by Peppersass »

You're doing a good job improving your distribution, and I encourage you to keep at it. This is time (and coffee) well spent.

But I'm sure you've been reading the thread, Working on Lumpy Uneven Mazzer Mini Doserless Grinder. Just read through it myself.

Although others may disagree, my conclusion is that most of the problem is with your grinder. While some feel that you should be able to get a decent pour from a Mazzer Mini, others do not. My own experience with the Macap M4, which is pretty-much a clone of the dosered Mini, was quite frustrating, though I had more problems with consistency than clumps, halo pours, etc. I ended up trading the M4 for a Baratza Vario, which solved a lot of problems and actually put money back in my pocket.

The Doserless Mini adds even more uncertainty to the equation. It's relatively new, and it seems that there are a number of issues with it that owners are discovering. When I look at the lengths to which owners are going to make that grinder perform, I ask myself, "Why are they bothering?". Yes, the Mazzer grinders are built like tanks and will last forever. All that means is that you will always have to struggle to overcome the shortcomings of your grinder. The Vario is certainly a better alternative, albeit probably with more maintenance required over time (recalibrating, tightening the belt, replacing plastic parts, etc.)

Good performance and consistence starts at about the Mazzer Super Jolly level. If you're willing to use a doser (which is no big deal IMHO), you can pick up a used SJ for close to what you can sell the Mini E for. If you must have a doserless grinder, then I'd recommend the Baratza Vario.

You should understand that the grinder is the second most important factor in espresso, right behind the coffee itself. I have a Compak K10 now, and wish I had just started with that grinder. Yes, it's double what you paid, but well worth it IMHO.