Bunn LPG versus Baratza Vario with Steel Burr - Page 2

Grinders are one of the keys to exceptional espresso. Discuss them here.
jedovaty
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#11: Post by jedovaty »

I must find myself one of these sieves to get an idea on grind settings. My b vario with steel burrs wouldn't go much coarser than what I'd call slightly leaning towards coarse drip grind, even after adjusting the hidden set screw per b's support recommendation. I have thought a french press grind was more coarse, not sure if anyone is familiar with the two grinders, but b virtuoso settings in the mid 30 (near the end at 39), or the big red grindmaster 500 at "drip" or even percolator setting.

Huh, interesting.

Netphilosopher
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#12: Post by Netphilosopher »

You can use the approximation for the three primary mesh sizes:

30 Mesh is 589-595 micron, 24 Tyler or 25 US Mesh is 701-707 micron, and 20 Mesh is 833-850 micron.

Since most grinders have a fairly predictable sigma (disc/burr types), an approximation of grind size by the amount of retention on a particular screen between 80% and 20% (or for more confidence, between 70% and 30%, because of the nature of distributions)

30 Mesh: Ave Grind = 8.56*(%retained) + 173.6
24/25 Mesh: Ave Grind = 9.4*(%retained) + 243
20 Mesh: Ave Grind = 11.55*(%retained) + 268.6

If you have 50% retention on the following:

30 Mesh ~ 600 micron
25 Mesh ~ 713 micron
20 Mesh ~ 846 micron

The effective ranges for the three screens:
30% retention
30 Mesh ~ 430 Micron
25 Mesh ~ 525 Micron
20 Mesh ~ 615 Micron

and 70% retention
30 Mesh ~ 773 Micron
25 Mesh ~ 900 Micron
20 Mesh ~ 1077 Micron (1.08mm)


This can also give you three points to establish a distribution, if you want to fit Cumulative Distribution Functions. Pass through gets the primary peak for grinds this size, but likely won't be effective for very fine grind.

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another_jim (original poster)
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#13: Post by another_jim (original poster) »

While this is all correct; it is fairly pointless. It has been established since the 1980s that sieving is not repeatable or accurate enough to characterize grind distributions. Even laser sizers are not fully accurate. An appropriately sized sieve is useful to get the initial grinder adjustment about right, but it cannot be pushed further than that. The chapter on grinding in Illy summarizes all the relevant research.
Jim Schulman

Socalsteve
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#14: Post by Socalsteve »

JavaMD wrote:I put a set of steel burrs in my Vario-w which I have paired with a Bunn Trifecta MB and noticed less bitterness and better taste after swapping out the ceramics. For pour over or press coffee it really seems to be the better set of burrs ....

Steve
Same here! And funny enough, my name is Steve as well...

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Merkinz
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#15: Post by Merkinz »

Con someone please direct me to where one buys these steel burrs that improves the Vario? Thanks :)

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yakster
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#16: Post by yakster »

You can buy them directly from Baratza here.
-Chris

LMWDP # 272

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another_jim (original poster)
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#17: Post by another_jim (original poster) »

I forgot to mention that the static issue resolved itself after a few days. Perhaps the burrs getting a slight patina does the trick. The burrs also sped up a bit, although they are still only half as fast as the ceramic burrs (about 1.2 seconds per gram as opposed to 0.5 to 0.6 seconds per gram).
Jim Schulman

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Merkinz
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#18: Post by Merkinz »

Oh thanks, I thought they were some aftermarket brand burrs

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