TGP II: Particle Distribution Analysis of Grinder Adjustments - Interim Results - Page 8

Grinders are one of the keys to exceptional espresso. Discuss them here.
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another_jim (original poster)
Team HB

#71: Post by another_jim (original poster) »

I'd really love to have an algorithm for knowing which of the things I don't know I need to know, and which I don't need to know. Until then, I'll persist in finding out how grinders grind. :roll:
Jim Schulman

Ken Fox

#72: Post by Ken Fox »

Marshall wrote:I think any "chicken or egg" discussion that tries to put the steps from bean to cup into a hierarchy of importance is doomed to become a freshman dorm mental exercise.

I have had too many good beans, properly roasted, which were obliterated in the hands of unschooled baristas, and too many commercial-grade bags from Italy, rendered as very drinkable espressos by skilled baristas, to take these discussions very seriously.
Well, welcome to the freshman dorm, Marshall; that's what most HB threads resemble anyway, so you are in the right place!

You are correct that with reasonably good technique, a competent barista can turn an inoffensive blend composed of stale and uninteresting beans into a "drinkable" espresso. If the beans are of such poor quality, by virtue of innate bad quality or bad roasting, very little can be done with them. However, you cannot get a really good espresso from anything other than really good beans which are still fresh.

I am not personally interested in drinking mediocre or bad espresso, or even "drinkable" espresso if it can be avoided.

What the equipment and the barista does is to try to coax as much of what is in the beans into the drink; they can't do any more than that. Basic barista technique combined with an acceptable level of equipment can produce an exceptional drink from exceptional coffee. The best barista in the world using the very best equipment cannot do the same with mediocre or stale coffee.

Since exceptional espresso demands exceptional coffee, the necessary but not sufficient combination of good technique and good equipment pales in comparison.

ken
What, me worry?

Alfred E. Neuman, 1955

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Arpi

#73: Post by Arpi »

it could be that coffee is a multidimensionally plural process. In a single process, there is a single cause effect relationship. In a plural process, there are multiple relationships (more complex). Multidimensionality means that things are not either black or white, but they can also be somewhere in the middle. Then you also have emergence. Good flavor emerges out of bad flavors (if taken separate) when combined in the right proportion.

Cheers

Ken Fox

#74: Post by Ken Fox »

Arpi wrote: Good flavor emerges out of bad flavors (if taken separate) when combined in the right proportion.

Cheers
This is how perfumers have made perfume from skunk oil, however I don't think it works very well with coffee.

ken
What, me worry?

Alfred E. Neuman, 1955

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Arpi

#75: Post by Arpi »

And how do they make blends? Don't they use sometimes 'bad' (incomplete by themselves) and make a better flavor? Isn't the result better than its parts?

Cheers

Ken Fox

#76: Post by Ken Fox » replying to Arpi »

I wouldn't use the word bad; it certainly does not have the same connotation, at least to me, as "incomplete."

There are a lot of reasons why coffee is (successfully) blended. Sometimes it is to take several unremarkable coffees and to try to make something out of them that is better "than the sum of the parts." This is the "Italian commodity blend formula." Sometimes it is to get unique flavors, without the constituent coffees necessarily being merely "acceptable." The latter would describe what is attempted by the better roasters.

ken
What, me worry?

Alfred E. Neuman, 1955

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HB
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#77: Post by HB »

Followers of this thread may be interested in Baratza Grinders - Particle Distribution at Various Settings. It shows a similarly-shaped distribution curve for the Baratza Vario at espresso settings:

Image
From the first post of this thread


From the first post of Baratza/Ditting results
Dan Kehn

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jpboyt

#78: Post by jpboyt »

I was playing around with an Azkoyen Capriccio M02 grinder this afternoon and noticed that when I cranked the stationary burr holder down till it rubbed, the rotating burr did not rub all the way around. This meant that the two burrs were not parallel and that they rub only when the two high spots pass each other. Being a machinist by trade I grabbed a dial indicator to see just how much runout I had in the rotating holder. It measured about .004". Rotating the lower till it was opposite the high point on the upper and cranking the adjustable down to the minimum gap, I came up with .006" upward travel required of the adjuster to stop the rub. Conclusion is that the difference in ejection gap varies by .006". This variance in gap spins with the rotating burr. It appears that I would always have this difference in a sample of ground coffee. The .006" equates to 152.4uM. This all lead me to wondering about espresso grind particle size which lead me to this thread. After spending much of today reading the material I am of the opinion that the data may: 1) reflect the mechanical deficiencies of a particular grinder and 2) may not be too useful for brand comparisons of grinders. I have been also doing studies and repairs on grinders used in high volume or extended low maintenance applications and am seeing quite a bit of bearing wear due to axial load and coffee infiltration. This may be one of the inherent advantages to the conical burrs because the burrs are predominantly radially loaded with the the axial load transfer being based on a cosine function of the conical burrs angle. There also is a range of stiffness values for the rotating holder based on material selection and bending moments based on burr diameter. Anyhow, I think all the testing is pretty cool, but I think that I would do some measurement of runout and axial play in my test grinder before I relied on my data too much. I was reading in another thread about someone comparing a Swift grinder to something else and saying that the new grinders were way more responsive to adjustments. My personal guess is that the Swifts were just plain tired and in dire need of grind chamber sleeving and bearing replacement. Those of you old enough to remember changing points on your car, remember how new points made your rig run better but sooner or later the thing needed rings and a valve job. New burrs are the same thing in a tired grinder. Runs better but not like a new one.
Thoughts?
James

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another_jim (original poster)
Team HB

#79: Post by another_jim (original poster) »

It's one of the 1,235,423 things that could go wrong.

However, I think you've happened to pick one that didn't. The problem with this data set is that all the particle distributions were so much alike that we couldn't make the distinctions we were hoping to make. That means either all the burrs were misaligned, or that none were, or that misaligned burrs do not show up on laser sizers.

Sadly, the thing that really went wrong is not one of the millions of things that can go wrong with espresso, but one of the millions of things that go wrong when engineering salespeople and payola labs overhype their toys. Laser sizers do not work to reliably distinguish the small grind changes required to keep the espresso flowing correctly.
Jim Schulman

Nick

#80: Post by Nick »

For what it's worth, I was talking to (the legendary) Don Holly at Green Mountain a couple of years ago as he took Trish and me on a tour of the GMCR facilities in Waterbury. One of the rooms he showed us was a room where grind analysis took place all day. They had a guy running a laser diffractometer, and they showed me how it worked. As you'd expect, they've got great-big roller mills that run for hours, and part of their QC is the grind analysis.

I asked Don about using the diffractometer to analyze grinds from different espresso grinders, and he immediately replied that the wavelength of the laser was not going to work very well for that grinds of that (small) size. For what it's worth. :(
Nick
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