Yes, your roller mill is sexy.
No, I am not willing to shell out that kind of cash. :-)
This page is designed to help people who own a Corona-style grain mill get better results on the cheap. It is not designed to convince anyone that a Corona is better than a roller mill, is a better value than a roller mill, or that it will bring about world peace or make us better looking.
Note that there are many Corona-styles mills out there (victoria, porkert, etc); I use Corona as a generic term to mean all such mills for the rest of this document.
Some collected tips
The corona is cheap and usually requires some fiddling. Here is how
to address some common tweaks needed to make it a workable part of
your all-grain or partial mash process. If you don't want to tweak and
adjust then pony up $150+ for a roller mill (and maybe have to tweak a
little anyhow).
grind is uneven - this is caused by plates that are not parallel, the most common complaint with coronas. Some are perfect out of the box; most are not.
I will work on these descriptions as I go; they are rough now.
some have taken the driven plate off and filed the side opposite of the grinding surface. I will try to get a pic of this.
Diablotastic says: "I removed that silly cotter pin which was applying uneven pressure to one side of the grinding wheel....basically pushed the grinding wheel up against the stationary wheel by applying pressure to the shaft that the adjustment screw would push on....then inserted an 8-32 screw in the cotter pin hole and tightened it up with a nut on the other side....this seemed to keep the plates more parallel then they were. The cotter pin seemed to be causing alot of the wobble"
flying ground grains fly everywhere - people have made plate covers and bought covers. I have used a butter tub upside down over the plates that the worked ok, but now I just wrap a bag around the plates; this greatly reduces free dust and eliminates the flying grains problem. Since I bag my mash grains for easy carrying anyhow this works great. This bag was one of the large bags that NorthernBrewer ships stuff in.
grinding is slow - It's slow, end of story. Takes several minutes of cranking to get through the grain. Some folks have removed the handle and attached a 5/16ths" bolt and drive it with a hand drill. This works well with a socket adapter so you can remove the bolt at will. Here's a view of mine. The socket adapter set (1/4, 3/8) came from Lowe's; Kobalt 280425, $4. A few run them off a pulley and dedicated motor.
hopper is too small - There is apparently a larger hopper you can buy, but many folks cut plastic bottles to fit.
too much flour in the grind - The corona will make more flour than a roller mill, for sure. But the flour can be minimized by getting your grind consistent so you don't have to overgrind. Take another peek at the close-up pic; there is no flour under the pile of grain, but there is a dust of flour on the grind.
torn hulls - no way around this, assuming you're not overgrinding as with the flour tip above. See the close-up again; the hulls are generally torn in half instead of whole-but-open. I have not had stuck sparges because of this, but if you are worried you can toss in some rice hulls. I do see little specks of black in my iodine test, and have been told this might be from hulls. So be aware of that side effect.
where to buy
The best way to get one of these is to find it at a garage sale of thrift store. $10 is a great deal; I don't think I'd pay more than $20. Since they are very heavy they tend to be expensive to ship. The chief virtue of these mills are that they are cheap and plentiful; paying too much defeats the purpose.
Note that sometimes people will list meat grinders as grain mills. They look similar but the output-end is different. Meat grinders have a cap with holes, and grain mills have a bracket that holds the grinding plates on, sometimes with a cover over the plates. Truly, the meat grinder will not work for grain milling purposes.
look around your local Hispanic grocery store. These are commonly used by our Latin brethren for grinding corn.
the mousepad
Yes, your roller mill is sexy.
