Burr Coffee Grinders
The burrs referred to in Burr Grinders is what grinds/curshes the coffee beans. Burr grinders give a much more consistent grind than blade type grinders and a uniform, consistent grind is important in creating a great tasting espresso or any other type of coffee.
There are two differenty types of burrs used in burr grinders.
The Conical grinders are aptly named due to the conical shape of the grinders. Two such ginders, with rough ridges on the outside of each, catch the beans between them to crush/grind the coffee beans.
A flat plate burr grinder uses two serrated and parallel rings. The beans are caught between the rings and as the rings turn, the beans are crushed/ground.
The motor in both types of burr grinders turns only one of the conical grinders or one of the flat plates. The other conical grinder and/or flate ring remains stationary and the beans are caught between the turning burr and the stationary burr. Both types of burr grinders give the uniform texture you need for a great tasting cup of coffee.
The other type of grinder (that is NOT a burr grinder) uses a blade to spin around and chop up the beans. The problem with this type of grinder is that the consistancy acheived is very poor. You will end up with fine powder and large chunks in the same batch. Blade grinders are generally not recommended by coffee lovers.