Originally Posted by
gugi
the linear grinding speed is not going to change with a simple two-pulleys system. the only thing you will accomplish is that the smaller wheel will make much more revolutions per minute than the larger wheel, and the relationship is linear, i.e. the wheel with twice smaller radius/diameter will spin twice as fast, the wheel with three times larger radius/diameter will spin three times slower.
however the speed that the belt is moving relative to the steel is going to be exactly the same on both wheels.
If you want to decrease the linear speed you'll have to use more complicated system where you have two pulleys stacked fixed on each other so that they always make the same number of revolutions per minute, and then the linear speed is directly proportional to the radius, i.e. twice smaller radius means twice smaller speed.