re: Any of you knuckle draggers ever built your own generator?

I said that in the context of mechanical efficiency. So the reason for using a large diameter roller or wheel at the end of the conveyor is to move the weight of the water in the buckets further away from the center of the drive wheel. Think of it in terms of a lever. The longer the lever, the more force is created with a given weight. So if you use a small diameter roller, your buckets will have to be much larger to create the same amount of downward force at the circumference of the wheel. Depending on what you are trying to accomplish, that may be ok. But if you want to maximize hp, use a larger wheel.