In the same spirit as the TGP II: Particle Distribution Analysis of Grinder Adjustments results, Kyra Baratza offered to share these laser diffraction particle distribution charts for their line of grinders. Unlike the TGP results that looked only at grinder settings in the espresso range, the charts below produced by Ditting/Baratza show the distribution at several grind settings. She thought they might be interesting to the HB membership and comments are welcome.

Baratza Maestro:


Baratza Virtuoso:


Baratza Preciso:


Baratza Vario:


PDFs: Maestro, Virtuoso, Preciso, Vario

Does this suggest the supposed bipolar/monopolar distinction between espresso grinders and shop grinders is more a function of grind setting (finest=bipolar) than burr design?

It's been my impression that no matter what the grinder design was, the finer you tried to grind with it, the higher the proportion of fines you would get.

That said, grinders will vary as to the relative proportions one sees when the peak(s) is/are adjusted for a desired size, and how concentrated those peaks are. As has been pointed out by others, there are significant differences between "brew" and espresso grinders that emerge when dialed in for different uses.

My thinking about these data has been modified a bit by the recent work from TGP II. The particle counters are not necessarily the be-all-and-end-all data generators I once thought they were, at least for coffee.

I really appreciate Baratza for publishing these plots. It would be fun to see one for a el-cheapo whirley blade or bean basher grinder to see the contrast between relatively inexpensive but well made grinders and the cheap competition. (Not really very relevant to espresso, though)

x2 on thanking Baratza for publishing these plots. if only more manufacturers would do this. i find these to be very insightful.

The proportional weight of fines declines as the grind gets coarser probably as as a matter of mathematical necessity, and has nothing to do with burr design. Every time a coffee fragment is broken, fines are generated, and a new coarse particle is created. So the ratio of fine to coarse counts stays roughly the same. This means as the coarse particles get smaller, the ratio of fines to coarse volume goes up. In the numerical datasets I analysed, this proportional relation of coarse size and volume is the strongest regularity to be found.

The Baratza distributions show a distinct change from the finer to the coarser espresso grind on the Vario and Preciso. We could not see this in our data with a 15 to 18 gram dose change; so presumably, the two espresso settings they used were further apart than this.