yakster wrote:You might be able to rent a roller mill at a home-brew shop for testing.

I have a roller mill of the type home brew shops use, and I can't imagine it would work well for coffee. Not about to try it on mine because I don't want to contaminate the rollers with coffee oils.

Home brew mills are generally set up with a fairly large gap. Their intention is to crush barley while leaving the husk mostly intact, rather than to grind to fine flour.

Yes, and no.

It is difficult to build small scale rolling mills.

It is difficult to build large scale disk mills. (what we hobbyists call flat burrs - the industrial processors call them disk mills).

The same companies that supply very large scale roller mills for industrial scale coffee processing also make coffee disk mills (aka flat burr grinders) with burrs up to 7" or 8" in diameter. Can you imagine a 200mm flat burr? Well, they exist!

The large industrial coffee processors do an amazing, absolutely amazing, job of controlling particle sizes and distribution of particles. They *have* to, in order to make consistent food service and retail products, like K-cups and capsules and even just plain old bags of consumer coffee.

I think I've come to terms that a mini roller probably isn't going to produce a great grind simply because the crushing surface area probably is too small for accuracy on a speciality scale. One thing uncommented also may be the noise level of one of these machines which is probably not suited for a retail environment. When you look at the speciality space it's grind on demand and these roller mills are going to be grind for mass order for a wide array of packaging, somewhat of a counter principal to speciality as it probably is going to push the coffee outside of it's speciality life cycle.

as an update to this BH just released a blog entry answering this question in depth about the use of roller mills and why there isn't a bench model. here's the blog entry for anyone interested. It pretty much says a benchtop model is possible but there isn't enough demand/tech available for it to be cost-effective (yet). I wouldn't be surprised to see crowdfunding projects emerging but maybe this is for the next wave (fourth wave?) of coffee.

https://www.baristahustle.com/blog/benc ... ller-mill/

The Barista Hustle article sort of ignores the place of the roller mills in the production process.

For example, I am not sure that roller mills create less fines. Now it is probably true that the grinding process creates less fines - but as C. Klatt explains in the Brita Folmer book - It isn't the burrs but they have special techniques To handle the fines (like puffs of air or a normalized to affix fines to boulders).

One cannot simply compare a Versalab or a Mazzer or a Mythos or a Kafatek to a "roller". A roller is just one step in a complex grinding process.

from what I understand and can quickly google rollers have a more consistent grind distribution but I don't know if this is before any purging of fines is done to increase consistency which certainly seems plausible in a commercial setting.

Roller-mills typically have 3 sets of rollers to progressively go finer and finer. If one of Hoffmann's recent video can shed any light on this grinding twice can be better for consistency and produce fewer fines as coffee doesn't get as much burr rotation contact from congestion. Hoffmann has to grind coarse and then feed the coarse grind really slowly and the result was a better distribution and a better overall extraction (according to Hoffmann). Now roller-mills don't feed coffee slowly but the nature of their design draws coffee downward and its triple pass system may very well produce something similar to what Hoffmann describes, a better overall consistency from a multi-grinding step system. I would think roller burr contact with the coffee is minimal and is instantly released rather than constant burr contact chipping away at whatever is left and congestion probably isn't an issue, certainly not like a disc or conical burrs.

But I"m just thinking out loud, in the end, rollers will find themselves in high production commercial setups and not in cafes or countertops.

I've posted about this topic in the past.

One of the bigger manufacturers of laerge-scale coffee grinder is Modern Processing Equipment.

https://www.mpechicago.com

You can get an idea of the scale of the rollers necessary. Usually you'll see three rollers in sequence for coffee. The diameter of the roller is important as the gap between them. The diameter controls the relative rate of compression used to shear the bean. The ratio of the bean size to the roller is part of the equation. The length of the roller in turn, sets the amount of material that can be processed.

The physical size of the rollers and the need for multiple rollers and big motors are what keeps them out of small scale use. They make a lot of sense for processing tons (literally) of coffee per hour.

The roller systems aren't "grinders" they are granulizers. They produce very uniform granules and that's backed up with process control labs in industrial settings.

The also make large scale disc grinders (aka flat burr) that can process 500lbs an hour.

The same technology is used for other food, mineral (like salt), pharmaceutical and chemical processing.

The smallest roller system they make is here:

https://www.mpechicago.com/product/lpp-65/

As you can see, it's pretty substantial.

that's a great distinction from grinder to granulizer and I think it's helpful comparing these things. I don't think a bench model is practical, perhaps a shop model but you would have to have a lot of demand to get justify it. If someone eccentric and rich enough wanted to force it you could have that LPP-65 model with the viewing/feeding area on the bar side with the big back end on the shop/kitchen side but according to the specs, it stands almost 6 feet talk with hopper so it might be a 2 man job just to get a 1kg of coffee. What could be cool is just having the view window on the bar side and feeding/output on the shop side and people can watch the machine at work grinding coffee away all day like some sort of stress reliever but the industrial noise the machine makes probably makes this not an option.