Roller Mill Grinder - Page 2

Grinders are one of the keys to exceptional espresso. Discuss them here.
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another_jim
Team HB

Postby another_jim » Dec 17, 2013, 1:59 pm

There's a company that makes these mills here in Chicago that claims they can engineer any particle distribution you want by adjusting the roller configuration. Their grinders are very cool if you like large machines; but I'm not certain about the claims.
Jim Schulman

Nate42

Postby Nate42 » Dec 17, 2013, 6:00 pm

I have a malt mill (for brewing purposes) similar to the ones in the OPs links. I don't think that specific type would work well for coffee, the knurls in the surface are pretty large relative to what you would want for coffee particle size. Brewers don't really care about even particle distribution, and with grain at least you get a lot of fine dust in addition to the larger particles. The thought has crossed my mind to run some coffee through mine to see what happens, but I thought better of it, don't want to contaminate the rollers (which thus far have only crushed grain) with coffee oil.

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Sardonic_Sardine

Postby Sardonic_Sardine » Dec 18, 2013, 12:00 am

Good point, Nate. The nature of the crushing surface on these home-use grain mills (and how that would affect the coffee grinds) did cross my mind.

I suppose this thread was more of a conceptual exercise, which could have potential lead to some (probably disastrous) DIY projects. I wonder if home/café grinder manufacturers have ever considered trying to make a small scale roller mill. I don't think that there would really be a need for a roller cooling mechanism similar to what Alan mentioned, given the relatively small amount of grinding it would do. Though as Tom pointed out, it might end up having several sets of rollers in decreasing order of grind size.

In the end though, it just seems as though the nature of roasted coffee makes the production of fines during grinding inevitable. Perhaps a wet grinding, home-use dual grinder/brewer? This grinder is becoming more and more convoluted in my mind!
"Really great things are evident to anybody who's paying attention." - Charles Babinski

jonr

Postby jonr » Mar 30, 2014, 9:37 am

A related question is if there is a way to remove the fines after grinding.

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Peppersass
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Postby Peppersass » replying to jonr » Mar 30, 2014, 1:36 pm

Great thread. Ever since I found out about roller grinders, I've wondered whether one could be engineered to be practical in a home or cafe setting. Evidently not.


There are screen systems that separate ground coffee into particle-size groups, but I don't know if they can be used to remove fines from espresso coffee grounds. I imagine if that's possible someone we know would have experimented with it by now, but I don't recall seeing any write-ups. I also imagine there could be some static issues that would make it difficult to get rid of all the fines.

Besides, as John said in another thread, it hasn't been shown that unimodal distribution produces a better cup. I guess getting rid of fines would speed up the flow, which would allow finer grinding (and presumably more fines to get rid of), but it's not clear whether all coffees would benefit and when the law of diminishing returns would kick in.