How do high end grinders perform better?

Grinders are one of the keys to exceptional espresso. Discuss them here.
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slipchuck
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Postby slipchuck » Jun 19, 2017, 4:44 pm

What is it about a high end grinder that allows it to get more consistent grinds?
The basic concept of the grinder seems simple enough.. a motor, a good set of burrs...
Is it because the more expensive grinder burrs aligned better then less expensive units? Or are they just more durable?

Any and all feedback is welcomed!

Thanks

Randy
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Charlene
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Postby Charlene » Jun 19, 2017, 4:52 pm

Oh lord! Now you're gone and done it, Randy! :lol:

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another_jim
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Postby another_jim » Jun 19, 2017, 5:35 pm

Grinders break beans into pieces, then break the pieces into smaller pieces, and so on. Like breaking a piece of toast or a cookie; when you break a bean, you get the pieces -- called grinds -- and the crumbs -- called fines. The ideal grind has pieces all the same size (so they extract at the same rate) and just the right number of fines to suit the brewing process -- no fines for steeping like French press, some fines for pourover, a lot of fines for higher pressure processes like vac pots or espresso.

That's about all we know for sure.

We used to think bigger grinders with bigger burrs were better since they had a longer grind pathways that broke the beans more gently. Moreover, a bigger grinder built to the same tolerances as a smaller one would have smaller relative errors. On the whole, this has been a fairly accurate rule of thumb. The 68mm - 71mm conical burr and the 64mm flat burr have been highly successful designs that have been used for decades. The 68mm conicals outperform the 64mm flats, which in turn outperform the smaller burrs found in most home, semi-pro, and commercial "decaf" grinders. That has been the status quo.

Recently, a new player, Mahlkoenig, a builder of industrial and lab grinders, has been moving into the cafe and home fields, building burrs for Baratza and under its own name. These have been smaller than the Italian burrs, and have performed well above expectation for their size. In addition, very light third wave roasts are not roasted long enough for the beans to get into their "glass phase," therefore, these beans are less brittle and pose grinding challenges for conventional grinders. It has become fashionable to use Turkish coffee grinders for these roasts. These two factors have posed some challenges to the conventional wisdom about grinder quality.

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Balthazar_B
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Postby Balthazar_B » Jun 19, 2017, 6:49 pm

Nice reply, Jim. And then there are the 83mm flats that are pretty prevalent these days. In addition to burr diameter, would you say that the relatively low RPMs at which these large grinders operate have a positive effect in the cup?
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Matt44
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Postby Matt44 » Jun 19, 2017, 8:52 pm

another_jim wrote:In addition, very light third wave roasts are not roasted long enough for the beans to get into their "glass phase," therefore, these beans are less brittle and pose grinding challenges for conventional grinders.


Didn't know this. Very informative, thanks!

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iploya
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Postby iploya » Jun 19, 2017, 9:33 pm

another_jim wrote:We used to think bigger grinders with bigger burrs were better since they had a longer grind pathways that broke the beans more gently.


This is potentially way off topic but has anyone ever tried developing a cylindrical grinder, like concentric cylinders with the burrs inbetween, so that the grind path is the same throughout and the beans are exposed to the same grind speed no matter where they make contact? I just don't know how you would adjust the coarseness that way.
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Postby bachampion » Jun 19, 2017, 9:44 pm

You're thinking is like a roller grinder that are used commonly for coffee grinding in bulk.
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ebola5114
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Postby ebola5114 » Jun 19, 2017, 9:47 pm

iploya wrote:This is potentially way off topic but has anyone ever tried developing a cylindrical grinder, like concentric cylinders with the burrs inbetween, so that the grind path is the same throughout and the beans are exposed to the same grind speed no matter where they make contact? I just don't know how you would adjust the coarseness that way.


A simple sketch of your idea could be really helpful to undertand,
Thanks!

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another_jim
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Postby another_jim » Jun 19, 2017, 10:36 pm

bachampion wrote:You're thinking is like a roller grinder that are used commonly for coffee grinding in bulk.


Yep, very good point. Cylindrical grinders are the gold standard of coffee grinding, since they can be calibrated for fines and grind particle size. So far they have only been used in industrial coffee grinding (i.e. mass producing cans of Folgers and Maxwell House). It would be very cool if smaller units made their way into cafes.

I get dibs if anyone wants to test a unit :D

osel
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Postby osel » Jun 19, 2017, 11:25 pm

What is THE ultimate home grinder for straight espresso?

If we're talking about low volume, preferably something small also to save kitchen space, but with best available quality? Monolith Conical? What tastes best in the cup and doesn't break or jam or is hard to operate? If price is not an issue.

 
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