What's the difference between a blade grinder and a burr one? I'm sure the same rule that goes along with purchasing quality clothes that last can be said for a quality grinder but I haven't been schooled in that aspect of life yet.
The difference has nothing to do with how long they will last (or even build quality really)...and everything to do with how they work.
A blade grinder doesn't really "grind
"...it chops...basically a tiny little food processor. The problem with this, is that you will never get the uniform grind that is required. The poster still hasn't mentioned his brewing method, but if you are using an espresso machine, you will never get the total uniformity required. And the problem with that, is that if the grind is not very
uniform, the water under pressure will simply find a channel in the puck, and never extract properly. You simply could not use a blade grinder for espresso.
A bit of a mute point, as anybody who uses a blade grinder for espresso machines, would also not be using an espresso machine capable of a good shot anyway. Inevitably, this person would also not have the necessary skills or knowledge to pull a good shot, and would also not likely be using quality beans either. These kind of people are generally candidates for the "push-a-button" crowd...Tassimo or any superautomatic espresso machine (which is actually the more expensive route in the long run, let alone getting the inferior coffee).
A burr grinder actually grinds the beans between two grinding wheels. Fine adjustments can be made, and depending on quality, uniformity of grinds can be quite good (less so on really cheap models). The really cheap burr grinders have a hard time with espresso grind, but it isn't impossible. The larger and slower the grinding wheels are, the better the grinds...slower grinding produces uniformity and less friction heat, which in turn is better for the grinds.