I said a couple of posts ago that Rotarycraft is the thinking player’s tech mod. What I mean by this is that the way one produces, transmits, and uses power in Rotarycraft requires of players a degree of problem-solving effort not needed by the other major tech mods (like Industrial Craft 2, Thermal Expansion, or Mekanism). Case in point: the grinder. The grinder is one of the Rotarycraft machines that you need to get up and running pretty early in the game. This is for two reasons: 1) it makes lubricant from canola seeds, which you have to have in order to use gearboxes (without which what you can do with Rotarycraft is extremely limited); 2) it is the mod’s early game ore-multiplying method. It triples ore output, but this is no cheap metal machine: you’re going to use lots of iron in the course of a Rotarycraft game.
But the grinder has certain power requirements, namely a total power input of at least 4096 Watts with a minimum torque of 128 Newton-meters (Nm). Here is where you run into the problem: there is no single engine that produces 4096 Watts at 128 Nm. Of those engines easily accessible relatively early in the game, none produce 128 Nm of torque, period. The DC electric engine produces 1024 Watts at 4 Nm, the wind turbine produces a maximum of 4096 Watts also at 4 Nm, and the steam engine produces 16384 Watts but at 32 Nm. This illustrates a recurring theme in Rotarycraft: even basic processes will require you to think and design power systems rather than just plugging X into Y as most other tech mods have you do.
In my case, what I did at first was connect the output of four DC electric engines using shaft junctions to produce an output of 4096 Watts at 16 Nm, then tried to use an 8:1 stone gearbox to change that output to the necessary torque. But without lubricant, the gearbox quickly degraded and failed to power the grinder. So what it looked like to me early in my game was that we had a catch-22: you can’t power a grinder without lubricant, but you can’t get lubricant without a grinder. And the same thing holds true when using a single steam engine, which produces plenty of energy by itself to power a grinder but not at the right torque.
Not knowing a great deal about the mod, I decided to link four steam engines together with three shaft junctions to produce the right amount of torque (32 Nm x 4 = 128 Nm). This method is expensive, though, taking a total of 100 steel, 4 gold, and 3 glass (or 88 steel, 4 gold, 3 glass, and 16 tin if you have mod that adds tin installed). It works just fine, powering the grinder at 512 rad/s without needing fuel. One last thing, though: if you don’t have netherrack and choose to heat the steam engines with lava, you also have to make four cooling fins which cost another 12 steel (or 6 tin and 12 copper, if you have access to those metals). Also, this doesn’t count the pump and DC electric engine that you have to build to keep water in the steam engines.
However, it turns out that there is a much cheaper way to power a grinder. The FTB forum has a page about getting started with Rotarycraft where it suggests waiting on the grinder until you’ve made ethanol crystals and a gasoline engine. A gasoline engine produces the same power as four steam engines (128 Nm at 512 rad/s for a total of 65536 Watts). In this case, you have to make a fermenter, a pump, and two DC electric engines to make the ethanol crystals. Total cost in materials, including the gasoline engine, is 72 steel, 5 redstone, 1 glass pane, 3 glass, and 3 gold (or 50 steel, 12 tin, 5 redstone, 1 glass pane, 3 glass, and 3 gold, if you have access to tin). This is, by far, the best way to go about getting a functioning grinder. Even so, a minimum of 50 iron (which is turned into steel in a blast furnace) is certainly more expensive than other common early game ore-multiplying mechanics (say those of Thermal Expansion or the even less expensive Tinkers Construct).
One side effect of all of this is that Rotarycraft is both demanding of creativity and surprisingly linear at the exact same time. There is one very specific sequence of machines that ought to be built, at least early in the game, because you cannot go very far in Rotarycraft without an ore-multiplying method of some sort. This isn’t a criticism, even though ideally I think it would be better if you had more than one way to move up in Rotarycraft’s technology tree, even early on. Fortunately, once you get some lubricant, it is possible to power even an extractor (which multiplies ore output approximately fivefold and produces by-products) with a gasoline engine and a gearbox (albeit much more slowly than it operates a grinder).
My current setup for producing lubricant, which will be changing very soon, is depicted here.
I am powering a grinder that is dedicated to lubricant production using only two steam engines (each producing 32 Nm of torque for a combined 64 Nm) and a 2:1 gearbox set to torque mode (producing 128 Nm). The lubricant is pumped out of the grinder into a reservoir, from which it is pumped back into the 2:1 gearbox and elsewhere in my base. The reason this setup will be changing soon is that it is just too slow. I have an automated canola seed farm that sits dormant half the time because there just isn’t room for more canola seeds. I’m toying with the idea of maybe using a hydrokinetic engine (a water wheel) for my lubricant production (since it uses lubricant itself). We’ll see how things turn out.