Blade grinders is often the cheapest and the worst for producing a very fine grind. They function by the internal blades cutting up the coffee beans and in addition to grind finer you simply need to keep the grinder running longer. Unfortunately, the resulting coffee grounds can be uneven in size, leading to inconsistent brew quality. Another major downfall, is that if you are grinding finely and therefore leaving the beans in the grinder for a longer period of time, there will be created significant heat by the blades. The created heat will give your final coffee a burned taste and vanquish some of the fresh essential coffee oils. These blade grinders are perfect for basic use when grinding for press pot or filter, but thats about it.
|Conical burr grinder|
Burr grinders are the notorious champions when home grinding for espresso or turkish coffee. Be aware of the two kinds of burr grinders; Wheel burr / Conical burr. In general the burr grinder function by moving a grinding wheel towards a non-moving surface and hereby crush the whole beans. The positioning on the burr is what regulates the ground size, which allows for a more consistent grind.
The less expensive burr grinder is the wheel burr, which has a high RPM and therefore spins the wheel very fast. The high speed of the wheel leads to noisiness, mess and a high temperature (The high temperature can likewise the blade grinders vanquish the essential coffee oils). The best choice for a home grinder is certainly a conical burr grinder, that functions opposite of the wheel burr grinder by having a low RPM, which makes them quieter and less messy. You can use a conical burr grinder for oily or flavored coffees and it is not likely to clog, like the other kinds of grinders. These are as mentioned before the best grinders, but you will pay a high price for them.
If you have chosen a burr grinder there a grinder types with flat and conical burrs, which each have some cons and pros. The flat burr grinders will make the beans go multiple ways in the bean path, because there are several sides, which means that the coffee beans have to change directions. A pros for the flat burr is that it cools quicker then the conical burr grinder.
The conical burr grinder are more temperature stable and the coffee beans is gravity fed directly into the conical burr. The quality conical burrs cut the whole coffee beans gradually down to the appropriate size, and flat burrs essentially crush the coffee beans and then cut it. The flat burrs is thereby giving a more homogeneous grind then the conical burr.
I would personally advise people to spend at least $200 on their grinder, because a good grinder is half the effort in the making of a good espresso. Even though you have a lousy old espresso machine like I, you can achieve amazing results with a proper grinder. Buying a good grinder also last a lifetime, so you will not have to change it, unless you really like to.
I have chosen a home grinder with 54 mm flat conical burrs, which I will blog about very soon!