Burr size difference in taste

Grinders are one of the keys to exceptional espresso. Discuss them here.
DavC

#1: Post by DavC »

Hi All,
Question :
Does a bigger burr size compared to smaller one with the same geometry improve the quality in cup? Considering maybe both are the same type of grinder, very similar burr geometry and both aligned properly (ie. Eureka 55mm specialita - 65mm XL/Zenith - 75mm Atom). Definitely can be other brands as well.
I'm not talking about in high volume situations, I'm just picturing a person trying to pull a couple of the best espresso shots.

baldheadracing
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#2: Post by baldheadracing »

Despite the quote from Hansung Lee (SSP owner) in my sig, I don't think that it is that simple.

For example, a while ago a few users went to the Compak R120 (120mm burrs), but I don't hear much about them now. Similarly, the Ditting 1203 is a rarity compared to the 80x. While machines these large have disadvantages in home use (the bag knocker on the R120!), I would suspect more people would have those grinders if the jump in quality from 98mm/100mm was there.

Also, it is hard to say "similar burr geometry." At the same rpm, a larger diameter has faster angular velocity. Are the designs still similar?

However, as a sweeping generalization, bigger flat burrs are often better, but size in and of itself may not be the actual reason.

Think of coffee. As a sweeping generalization, bigger beans are tastier than smaller beans. Entire country's grading systems are built on this, e.g., Kenya. However, it isn't the size itself, it is just that healthier beans are more likely to be larger.
- My espresso: Swirled, not stirred. My pourover: Stirred, not swirled.

TallDan

#3: Post by TallDan »

Burr size is part of it's geometry. You can't have burrs of different size and the same geometry. It's as simple as that.
Geometry is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that are related with distance, shape, size, and relative position of figures.

baldheadracing
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#4: Post by baldheadracing »

TallDan wrote:Burr size is part of it's geometry. You can't have burrs of different size and the same geometry. It's as simple as that.
A triangle is still a triangle regardless of size.
- My espresso: Swirled, not stirred. My pourover: Stirred, not swirled.

TallDan

#5: Post by TallDan »

But a big triangle is different than a small one. They can be substantially similar in many ways, but not the same.

80mm flat burrs and 64mm flat burrs are going to be different.

Bottom line though, it's probably an academic discussion with little practical value. Burrs are the most critical, but only one part of a grinder. If I can fit either 64mm or 80mm in my grinder, I'm going to want the 80mm, all else being equal. It's extraordinarily rare to have a grinder that can fit both, in part because there's not much benefit to putting small burrs in a big grinder.

If I'm choosing between a mazzer major and a lagom p64, I'd choose the lagom. But those two grinders have very little in common other than flat burrs and electric motors, even if those properties make them substantially similar.

baldheadracing
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#6: Post by baldheadracing »

As an aside, the large inner diameter of the Major burrs makes them 'smaller' than their outer diameter might imply. Dimensions here: Bigger burrs fact or myth? (in the cup)
- My espresso: Swirled, not stirred. My pourover: Stirred, not swirled.

henri

#7: Post by henri »

So let's suppose we magnify an x mm burr by some amount y, keeping relative dimensions identical ("scale invariant geometry"), and also adjust RPM so that the angular velocity at the perimeter is the same. Would these two configurations behave identically?

That's the null hypothesis, and I'd say it's up to adherents of the opposing view to demonstrate some mechanism which would give rise to a difference in the cup / in the particle distribution.

BaristaBob

#8: Post by BaristaBob »

TallDan wrote:But a big triangle is different than a small one. They can be substantially similar in many ways, but not the same.

80mm flat burrs and 64mm flat burrs are going to be different.

Bottom line though, it's probably an academic discussion with little practical value. Burrs are the most critical, but only one part of a grinder. If I can fit either 64mm or 80mm in my grinder, I'm going to want the 80mm, all else being equal. It's extraordinarily rare to have a grinder that can fit both, in part because there's not much benefit to putting small burrs in a big grinder.

If I'm choosing between a mazzer major and a lagom p64, I'd choose the lagom. But those two grinders have very little in common other than flat burrs and electric motors, even if those properties make them substantially similar.
So you would choose the Lagom P64 based on the intangibles rather than burr size...correct?
Bob "hello darkness my old friend..I've come to drink you once again"

TallDan

#9: Post by TallDan »

You have to consider the burr in three dimentions, not just two.

The angle of the cutting surface will be different. Borrowing a picture from another thread:
Image

A larger burr will have shallower angles for the grinding surface than a smaller burr.

Call that a "mechanism" if it satisfies you.

baldheadracing
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#10: Post by baldheadracing »

I think that the thing to remember is that nobody seems to know how to design burrs for taste. Tasting "boxes and boxes of burrs" seems to be the development process ... at least given public statements by Mahlkoenig/Ditting and Conte Valerio/Eureka/Nuova Simonelli/Victoria Arduino.
henri wrote:So let's suppose we magnify an x mm burr by some amount y, keeping relative dimensions identical ("scale invariant geometry"), and also adjust RPM so that the angular velocity at the perimeter is the same. Would these two configurations behave identically?

That's the null hypothesis, and I'd say it's up to adherents of the opposing view to demonstrate some mechanism which would give rise to a difference in the cup / in the particle distribution.
No, because the centrifugal force loading the burrs with coffee would be different.

In addition, the, for lack of a better term, triangles at the outer parts of the burr would be sized differently.
- My espresso: Swirled, not stirred. My pourover: Stirred, not swirled.