The goal here is to crack the cocoa beans into pieces and then separate the husk from the nib.
To make chocolate, this husk needs to be fully removed. It can be done by hand, but this is rather tedious.
Running the roasted cocoa through a very course mill (Corona type) to just crack the cocoa beans into large pieces (called nibs) and then blowing the husk (chaff) away (winnowing) is another option.
A meat grinder set on very coarse does not work. It just pulverizes the beans and does not allow separation.
After proper roasting, you will notice the outer husk is much looser and easier to remove. It sounds simple enough but a year ago, there were not many pieces of equipment that worked off the shelf. We contacted two companies to see if they had any interest in modifying one of their products to handle cocoa beans.
CrankandStein worked with us and we are happy and proud to offer a heavy three roller, dual drive, set gap mill. You can see it in action below. It is a breeze to crank and easily does 4 lbs/min. It also has a 1/2" shaft that will fit most drill chucks if you with to motorize it.
The CrankandStein Cocoa mill in action
A few notes: For winnowing, just use any old hair dryer, although a small shop vac works great. Come in high and stir with your hands (or those of your apprentice, you can see my daughter Logan helping above). You will soon work out how close the blowing air needs to be to blow the husk away, but not the nibs. After a few minutes, you should have a nice bowl of nibs ready for the Champion Juicer. Don't fret too much about a few pieces of husk here and there. The screen in the Champion will remove those few bits, and actually make a very nice filter bed.
Also, the mill does just fine on the Raw cocoa beans. You can make your own raw nibs for adding to various raw food recipes. In this case, it usually takes two passes as the husk adheres to the beans more than when the cocoa beans are not roasted.
Finally, if you don't want to bother with a mill and have access to a Champion Juicer this does a marvelous job of grinding and separating the husk all at once (See Grinding for details).
It may be that with the juicer, separate cracking and winnowing may not be necessary for home made chocolate batches. I plan on taste testing cracked and winnowed chocolate vs. Champion separated chocolate in the future before I give my final opinion. So far I do not notice any unpleasant or off flavors from grinding with the husk intact. I will update this more as I gather information.
One thing I do notice though is with winnowed cocoa nibs, there is less wasted cocoa liqueur and the Champion does not have to work as hard so at the present time I would advocate cracking and winnowing before grinding.