WDT - what causes uneven distribution in the first place? - Page 2

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

coffee_plXR wrote:Witnessing the difference, I definitely couldn't miss the advantage of WDT, even though it's tough for me to repeat this on every single shot.
That's helpful, but I was asking for a photo of the coffee as it "lands" in the basket. Judging from the lopsided pour, my guess is it's throwing the grounds heavy to one side; rotating the portafilter while the grinder fills the basket could help. Posting a video of your preparation from start to finish would be helpful, otherwise there's a good chance we're missing a contributing factor. See Spot the errors in my barista routine for an example.
Dan Kehn

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#12: Post by cafeIKE »

If you can, remove the PF support.
Make a set of spreaders for different doses:

Move the PF handle as much as possible to get a better distribution from the grinder. I use a collar and grind directly into the PF on the Niche, moving it about to get an even distribution.

Tap the PF V E R T I C A L L Y to settle. Start spreading with a couple of rotations. Tap PF again, continue until there is no more coffee in front of the spreader. No WDT required.

BTW, while the shot looks better, there are still blank areas. Drop the dose ½g and grind just a tad finer. Adjust as necessary.


#13: Post by DamianWarS »

coffee_plXR wrote:Thanks Dan:)
I still didn't get used to post picture properly, I just uploaded that big original ones It might get you a bit hard to go
(I have no idea for downsizing it.)

So here's the grinder

1. Without WDT

I use 1) distribution tool, 2) PUQ tamper only, and then go straight to espresso.

You see the extraction coming from the left? It happens everyday when I'm not using WDT
In my opinion, It at least shows that the density of the coffee grinds on one side is heavier than the other. But why this happens is a tough question.
In my case, the extraction occurs mostly on the left side(the right side is mostly clogged). I think it occurs randomly if it should happen because clumping doesn't tell any left or right side.

2. With WDT

On top of the previous prep, I added triangular whisk to stir coffee grinds.

Here's the change.

Witnessing the difference, I definitely couldn't miss the advantage of WDT, even though it's tough for me to repeat this on every single shot.

By the way, can you recommend me any doserless grinder in the light of this?
I think I'm going to buy Mazzer Major VP, but not sure if it can handle this problem.
Those shot differences are drastic. I think I would agree with the conesus here, without a form of WDT there is a problem with an uneven density in the puck. One thing you could test is after you tamp rotate the basket to see if that unevenness moves with the rotation. If it does the problem would point to the puck and you should be able to isolate which side is more dense. After you tamp you can also gently press your finger into the dry puck and it should confirm that one area is less dense then another area too.

I know this doesn't seem to be the issues but I would ensure the basket and shower screen are clean and also the water coming out is even. I would also check if you machine is level. They are all easy fixes should and it would just eliminate those as a factor.

If distribution is the issue there are other methods over WDT that may be more to your liking. As a cafe you probably don't want to add a long list of things to your prep and just want something that is easy to use and gets the job done. Duomo may have something easier for a bar workflow as it's more of a spinning tool. If you've identified your problem but WDT is too difficult to add to your work flow it's just a matter of using something else to distribute the coffee more even. It could be as simple as rotating the PF as it's dosing.

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#14: Post by AssafL »

From my experience there are a couple of reasons for uneven extraction:
1. Tamping an uneven bed. This is the classic "tamping a pile of coffee and getting a donut extraction". Obviously, tamping a pile that is on the left meaning less flow from the left. Why? Because the density of coffee will be higher where more coffee was pressed down.
2. Uneven particle size distribution. Even if the bed is flat, the density of each particle size must be homogenous (left to right, up to down, etc.). Imagine laying a math paper (with squares) on top of the puck. Each square should have the same number of particles - and the exact same particle histogram.
3. Fissures in the puck. That cause spritzers, channels and the like.

Boulders are heavier than fines. That means that as particles get discharged from the fast rotating blades the fines (that would "float down" rather than fall) would separate from the heavier particles, that would in turn separate from the high momentum boulders.

Now - do Illy or Nespresso "stir" the coffee in the pods? No. So Christian Klatt from Hemro - Mahlkonig (in the Brita Folmer book) talks about grind normalization (making a uniform density mix) and agglomeration (connecting the fines to larger particles so that they don't float away).

Very few "home" and SD style grinders do a good job of that. Dozers did a reasonable job. Some, like the EG-1 come with a shaker to do the normalization and agglomeration (simple solution that works well - and worth buying). Others have a sup and a whisk.

The only grinder I know that absolutely does not need it is the Versalab/Titus. The grinds are stopped at the burrs (less than a mm for them to separate until they hit the side of the grind chamber). They fall down while a paddle stirs them and agglomerates them. Homogenous to the extreme - but still it falls in a donut shape and you have to flatten the coffee bed (a knock or two). I slowed it down to 200RPM or so the make the donut even wider.
Scraping away (slowly) at the tyranny of biases and dogma.


#15: Post by nick_111 »

As already mentioned by others, the root cause of this unevenness is probably due to that the coffee does not fall evenly as you grind into the portafilter. You might want to take a look at this video on coffee distribution, which addresses exactly this issue: