I have a Crank&Stein 3 roller geared up in a custom mill cabinet. I don't recommend it, unless you are super engineering savvy about motors and belts and whatnot.
I used to have a regular Crank&Stein 3 roller in the mill cabinet, and it often time wouldn't catch. The rollers would just spin, malt wouldn't go through, and then you had to grab the pulley wheel and the bottom wheel together to grab the grain while off, or turn it on and bump the bottom roller with your hand to get it to catch and start milling. It was really a pain in the butt to use, especially trying to use it as our regular shop mill.
So I upgraded, bought a new crank and stein 3 roller, but this time geared up so all 3 rollers would turn under power. I installed it the same way as the old 3-roller was, turned it on, put some grain in, and it jammed. Rollers wouldn't spin. Tried to back it out and see what was happening, jams again. I called him, asked what was going on, the old one slipped but never jammed, why is the geared version jamming? He basically refused to give me advice and said it's not his rollers that's the problem, it's my motor isn't strong enough and the belt is clearly slipping.
To this day, it's gotten a little bit better, but things like wheat and carapils still jam it, crystal malts too, things that are really brittle will jam it up and it won't move. When it does mill, it does a decent job, it kinda pulverizes a bit too much, and creates a considerably large amount of dust.
So, coupling an issue with the mill itself, and mediocre to poor customer service, I can't recommend doing it.
Best purchase I've ever made was the SS Brewtech Mill. It's pretty expensive, but I love it. It's an incredible mill, and literally it's only downside is that it runs a little slow, on their website it says 350 lbs. per hour, 5.8 lbs per minute, The crank and stein does go incredibly faster than the Brewtech mill, but the crush isn't as good. Easy tradeoff.
