Slight modification to the Weiss Distribution Technique - Page 3

Beginner and pro baristas share tips and tricks.
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RapidCoffee
Team HB

#21: Post by RapidCoffee »

ChadTheNomad wrote:Is there any conclusive evidence that extraction faults, including channeling, are caused by clumping during dosing rather than faulty tamping, a bad grinder, some fault in the shower screen (I suffered from this at one time).
Good question, and the answer is no. There is little conclusive evidence for anything in the espresso world. From personal experience, I found that severe clumping makes it difficult to get an even distribution of coffee grinds in the puck, which is one likely cause of channeling. But I have no conclusive evidence of this. (The other issues you mention are irrelevant in my case. Extraction flaws went away when I fixed distribution problems.)
ChadTheNomad wrote:It would seem to me that these types of faults would only be present if there were no tamp at all. Sufficient tamping force would almost certainly normalize any inhomogeneities in coffee distribution, would it not?
Easy enough to test. Create a really uneven distribution of coffee (e.g., push all the grinds to one side of the basket), and then tamp as hard as you want. Let us know how it turns out. :roll:
John

popeye

#22: Post by popeye »

Marshall wrote:O.K. After accusing WDT fans of being anal-compulsive fetishizers :D , I finally accepted (sort of) that it might be of some (minimal) help to owners of cheaper or doserless grinders. But, now I'm flummoxed. What is it you think your Super Jolly fails to deliver that needs fixing with these rituals?
Ok, Ok, I don't need to WDT. But i actually gave the super jolly to my brother and have a mazzer mini now. It still produces a great grind, but I haven't developed a good stockfleth's move. So I've been sticking with the routine I started ever since I had cheap grinders: grind into the portafilter (yogurt cup adapter helps me overdose slightly), WDT for distribution (vice clumps) and then tamp. I have the filter basket out of the portafilter this whole time, so I tamp 80% and spin the basket with the tamper still in it. If the tamper wobbles, or I can see the side of the tamper rise and fall compared to the side of the basket, I use the remaining 20% of the tamp to fix the tamp to level. Lock and pull. My mazzer has the doserless soda bottle mod, but i still don't really get clumps. If i worked on a stockfleth move, i could stop the WDT. I probably should, actually, because my long range plan - once i get out of the military - is to open a coffee shop. Can't do any WDT there!
Spencer Weber

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HB
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#23: Post by HB »

ChadTheNomad wrote:Is there any conclusive evidence that extraction faults, including channeling, are caused by clumping during dosing rather than faulty tamping, a bad grinder, some fault in the shower screen (I suffered from this at one time).
I don't think it's the clumps per se that cause the problem, but rather the uneven distribution they engender. Clump = compressed coffee = different weight per volume.

It would be easy to test this theory. Anyone with a "clump monster" grinder willing to dose into a basket and then carefully divide the basket's content down the middle (ambitious home baristas may prefer the "baked puck method" Jim did for measuring extraction solids)? My bet is the WDT puck will be less than a gram difference side-to-side and the clump monster basket will be all over the map. A three gram difference for a double is my guess for the tipping point between a barely acceptable extraction and a disastrously uneven one.
Dan Kehn

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Marshall

#24: Post by Marshall »

popeye wrote:I probably should, actually, because my long range plan - once i get out of the military - is to open a coffee shop. Can't do any WDT there!
So, reading between the lines, you gave away your Super Jolly so you could serve your country and be razzed by some civilian jerk in a desk job. Sorry. :oops:
Marshall
Los Angeles

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ChadTheNomad

#25: Post by ChadTheNomad »

HB wrote:I don't think it's the clumps per se that cause the problem, but rather the uneven distribution they engender. Clump = compressed coffee = different weight per volume.

It would be easy to test this theory. Anyone with a "clump monster" grinder willing to dose into a basket and then carefully divide the basket's content down the middle (ambitious home baristas may prefer the "baked puck method" Jim did for measuring extraction solids)? My bet is the WDT puck will be less than a gram difference side-to-side and the clump monster basket will be all over the map. A three gram difference for a double is my guess for the tipping point between a barely acceptable extraction and a disastrously uneven one.
I guess I haven't really faced serious clumping issues, but the way you describe it makes perfect sense to me now. For some reason the notion of a difference in weight didn't strike me, but it seems so obvious now.

I might be under the mistaken impression that my Mini + rotating PF during dosing + distribution method and tamp addresses any of the small clumps, but I'll give your test a shot this week and see what I come up with.

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HB
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#26: Post by HB »

I encourage you to try it, but I don't think the Mini qualifies as a clump monster. The doserless Rocky Rancilio and Macap MC4 are better candidates for clumpy grinder poster child, as well as John's modified doserless Super Jolly grinder:

Image
From Banish Uneven Extractions

To make matters even more interesting, the Titan Grinder Project revealed that all clumps are not created equal. The Macap MXK extruded boulders of coffee grounds, and yet it was oh-so-easy to dial in the most picture perfect, evenly extracted espressos.

Image
From John's writeup of the Macap during the Titan Grinder Project

There's some other factor in play that I have not figured out...
Dan Kehn

Nickk1066

#27: Post by Nickk1066 »

I think one way to fix the clumping would be have a small rotating cog in the chute driven by the movement of the burrs.

There's obviously a few ways to deal with clumps:

A) Deal with the cause - compression of grounds.
My thought is that there's two causes that spring into my mind:
A1) Mechanical compression caused by the mechanical grinder components. The only way this is to be resolved is to redesign the chamber/parts with an eye on fluid mechanics. Powder does behaviour close to a fluid so by looking at the pressure model within the chamber one can see the points where mechanical compression will occur.
A2) Ground compression caused by the later grinds bumping to previous grounds (in the same grinding). This is caused by the lack of flow through either the design of the chamber or the friction/electrostatic attraction to the grinder wall. This causes a laminate flow effect and the grinds will quickly build up and compress as they will not smoothly pass each other like water. The resulting back pressure causes the compression and clumping.

This doesn't cover oil adhesion or static clumping which as others have had fluffy grounds into doser for the SJ, then I've ignored these!

B) Deal with the result - the clumps after they're created.
B1) break the clump in the grinder - that's a doser, intricate chute design component to break clumps.
B2) break the clumps in the basket - WDT etc.


Do I think that clumps affect distribution and aid channeling - I believe they do. However the tamping and extraction are key. Using a MCAL then you don't have a massive amount of force pushing the water through the puck so it's easy to choke if you over pressure in the tamp. I'm only 13 stone so I'll put the majority of my weight on it.. what pressure that is I don't know but I have a feeling it may be lighter than some tamping that goes on here.
In addition perhaps the fluffing causes less coffee volume - this is entirely possible but the end result is the important point rather than the method. This works very well and consistently.
Barista - applied pre-emptive hydro-thermodynamicist.
(#208)

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RapidCoffee
Team HB

#28: Post by RapidCoffee »

HB wrote:...I don't think the Mini qualifies as a clump monster. The doserless Rocky Rancilio and Macap MC4 are better candidates for clumpy grinder poster child, as well as John's modified doserless Super Jolly grinder.
To make matters even more interesting, the Titan Grinder Project revealed that all clumps are not created equal. The Macap MXK extruded boulders of coffee grounds, and yet it was oh-so-easy to dial in the most picture perfect, evenly extracted espressos.
There's some other factor in play that I have not figured out...
When the TGP began, conical burrs were all the rage. Some of that buzz has since died down, but one finding received fairly unanimous support: conical burr grinders are more forgiving. Conical burr grind settings are easier to dial in, and need less adjustment than flat/planar burr sets. Why? Who knows. But that's probably the "other factor" you're looking for.
John

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dsc

#29: Post by dsc »

Hi everyone,
Powder does behaviour close to a fluid so by looking at the pressure model within the chamber one can see the points where mechanical compression will occur.
I'm not so sure it does as it sticks to almost everything (coffee powder that is), clumps, doesn't want to 'flow' even when sticking outside it's support and doesn't always go down when it should (plus fluids don't really like to compress do they?). The reason why grinders clump is the way the 'throat' between the burr chamber and the rest of the grinder is designed. It's usually an inch long flat corridor which holds quite a lot of grinds, compresses them and when there's no room left for them they fall out on the other side, but already stuck to each other in the form of clumps.

WDT seems to work well and reduces clumping, but if you overdo it it can do bad things (already mentioned).

Regards,
dsc.