As well as allowing us to ‘top & tail’, or ‘top or tail’ our grind distributions, sieves can also tell us something about our grind distributions.
I decided to dedicate one of my grinders (Lido 1) to optimising via my Kruve, but still allowing for use without sifting, for days when I just didn’t fancy the additional effort. Immediately it was obvious that 400 & 800 size sieves excluded a huge amount of my grind distribution with my Lido 1. Also a grind centred between these sizes was too fine for my regular drip brewing method. Therefore, I fitted the largest size I had (1100) in the top section and a reasonably fine sieve (350) in the lower section. This gave me…
At setting 0.50 from marked zero I landed 69% of the ground weight between 350 & 1100 sieves. This suggests my standard deviation for this grinder is less than 1.773, calculated as SQRT(1100/350). As an aside, I found that 400 & 1100 sieves gave me 68% between them and a standard deviation of 1.658 for this grinder, in this range. (SCAA & ECBC drip grind recommendations echo E.E. Lockhart’s 1950’s analysis, aiming for a standard deviation of 1.414, but this does not seem to be absolutely necessary for smaller brews).
Setting 0.63 also landed a healthy 66% between these sizes, with an even balance between sub 350 (16%) & larger than 1100 (18%) particles. Note that there is typically a bias towards the smaller end with most usable grinds, so this shows I am already coarser at 0.63 than will leave me with the average grind setting targeted by these sieves (620 Kruves). This would be an ideal place to stop, however, this was still slightly on the fine side for what I wanted, with my 1-mug V60 brews averaging 21.5%EY without sifting & removing any portion. I would be happier with a 20.5%EY average for a complete grind distribution, though I can exceed this happily when removing the largest 15-20% of ground weight.
Setting 0.75 gave 62% between the 350 & 1100 sieves. This is not a sign that the distribution is getting worse, but simply that I am now so coarse that I won’t fit the distribution within these sizes to +/- one standard deviation. Again, note that the sub 350 particles are now a much lower % than those larger than 1100.
Another way to view these results might be like this, with cumulative & diminishing weights at each interval, for each setting…Cool, eh? Kind of ‘X-ey’ 🙂 But probably a little hard to grasp until you blank out the area above 50%…
This now gives us a more intuitive hump/peak type diagram. The farther left the apex of the trace, the finer the grind. The farther right the apex of the trace, the coarser the grind. The more acute the angle between the cumulative & diminishing traces for the same setting, the tighter the distribution. The more obtuse the angle, the wider the distribution. Look at how the black ‘0.75’ trace almost touches the red 0.63 trace at 350. Blue (0.50) & red (0.63) traces are very similar & virtually parallel between 350 & 1100.
For now, I have settled on setting 0.69 with 500 & 1100 sieves. I get a maximum of ~20% under 500. This allows me to save a little time by being a coarser than I need to remove the bottom 15%, or so, for immersion brews. The 500 is also quicker & easier to clean.
This setting also retains ~20% on top of the 1100, which I discard for drip brews. Kruve have just announced availability of larger sieves, so I intend to replace the 1100 with a 1200, to allow me to sift out either the bottom 15% or the top 15% at will, depending on brew method.