<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tom Chips:
I want to understand the small details as to why a cheap grinder wont work as well. </div></BLOCKQUOTE>
There are a few factors... The cheapest grinders use a blade to chop up the beans. This can create particles of many different sizes in the grind. These particles will extract at different rates. The smaller pieces (including dust) will extract faster and will over extract, adding bitter notes to the coffee, and the larger particles can under extract and add a sour note to the coffee. Also, the degree of grind is controlled by how long you grind and reproducibility is difficult.
The next step up is a bur grinder which uses toothed burrs to grind the coffee. These can be set for a specific grind level so you can reproduce the same grind every time. The difference between burr grinders of different price levels is based on on the size and type of the burrs (flat vs. conical), the strength of the motor, and the mechanism that holds the burrs. Better grinders will have larger conical burrs with bigger motors and mechanisms that allow very minute adjustments (sometimes even "stepless" adjustments) and do not drift from a setting. Less expensive burr grinders will have coarser adjustment, smaller burrs and smaller motors.
For drip coffee most people can use a blade grinder without noticing the difference. If you are concerned about being able get the same results every time then go to a burr grinder. Again, for drip, the less expensive burr grinders will work very well.you For espresso, in order to dial in the proper shot timing (approx 2 oz of espresso in approx 25 seconds) you need the ability to adjust the grind in fine steps. This is why I recommended the Cunnill Tranquilo earlier in the thread. For an espresso grinder it produces a consistent grind with very little dust and has enough adjustability that it will allow you to dial in the grind properly.
Don't over look used or regurb commercial grinders for espresso. I bought a $900 commercial grinder for $75 on eBay a couple of years ago, spent $45 on new burrs and I have a fantastic grinder!