Great question; glad to see someone actually asking these questions.
There are certain scenarios where some of these things matter more:
- If you're going to be crushing a lot of grain, you wanted hardened rollers. If you plan to become an operating nano brewery- go with the hardened rollers, if you do large batch sizes or brew often, go with the hardened rollers.
- If you plan to wet mill or if your brewery is in a wet location, consider stainless rollers; you can get away with normal or hardened non-stainless rollers with 2% water malt conditioning, though.
- If you brew a lot of light beers or really hate husky, tanniny astringincy you want to lean towards technology that will shred the husks less: this means geared rollers (both rollers are powered and driven at the same speed, or slotted rollers, or stainless rollers so you can safely malt condition/ wet mill.)
- The bigger your brewery gets, the more important efficiency is; the standard easy gain here is 3 or 4 or even 6 roller mills for the giant guys. Fluted rollers help as does wet milling or malt conditioning. Note: Wet milling or malt conditioning helps gain efficiency because you can set the mill gap smaller without shreading the husks.
Personally the feature I'd really like to see in a mill is geared rollers; it's available in the Schmidling but they really don't have any turnkey options available. There's a mill that's becoming widely sold in the UK called the "Bulldog" -something like that that has geared rollers. I love the feature as it means that both rollers are powered and spin at the same time, which HUGELY reduces the torque/ tearing forces on the grain husk and results in more intact grain husks. -It does require a slightly more powerful motor, though.
You also need to remember that with the larger diameter, longer length mills and with 3 roller mills you will need a more powerful motor to turn them. -A battery powered drill won't power all mills.
I also think another important feature is the mechanism that locks and adjustable mill into place and ensures that it doesn't move when you don't want it to. (As Monster Mills learned from their early products.)
If you plan to brew a lot of beers with wheat, you'll want an adjustable mill, too; you really want both sides to be adjustable and again you want a design that will hold the gap you set well.
The fluted / slotted rollers are interesting, and more like professional rollers; as far as I know only the "Captain Crush" from Northern Brewer and the new MM-2Pro SL, which is a response to the Captain Crush offer the feature. They do help with shreding husks, but not as much as a gear that ensures that both rollers spin at the same speed. -See my frustration there? -The Captain Crush has some pretty terrible reviews and most of them seem to be with the non-powered roller not spinning. I just can't understand adding fluted rollers as a feature BEFORE geared rollers.
If you plan to ever power your mill with a motor; even if it's a POSSIBILITY pay the like $9 extra for a 1/2" drive shaft vs. 3/8"; so wish I would've done this.
Per Monster, hardened rollers can survive up to 10x as long as unhardened so it's not an insignificant difference...
Adam
