How fine do you need to grind for auto drip? Do you need th grind very fine - just coarser than espresso fine? Do you need to grind on the coarse side to keep the water flowing through the filter? All these and more questions are swirling in my head - overwhelming me with the complicated combinations of perportional perfection. What is the easy answer? If you dig for the truth about coffee like some over caffienated version of the X-File's Molder and Scully then follow with me - the truth is out there.
Actually the truth is in your kitchen, and my kitchen, and the answer is different for any one who owns a different grinder or coffee maker than you do. Thankfully the difference is not of a radical magnitude - great coffee prep, like football, is a game of inches. Some universal truths apply to all combinations. If your grinder will only grind one way - a blade grinder for example, then your prep method is simplified - you are dismissed early, go enjoy some coffee.
Now that we got rid of those guys, the rest of us with adjustable grinders can get down to the business of perfect coffee. But first a word about those flat burr crushing type grinders - coarse will be a mix of coarse and fine and will not behave in a way that makes sense with the rest of this blog's assumptions - why not adjust pretty fine and leave it there - this is the best consistency you can count on.
The rest of you with an adjustable burr grinder - flat or conical - can get ready to grind the beans for your perfect pot. If your coffee maker is small - a four cup model, be prepared to rind finer than your instincts tell you to - the water runs faster through a smaller ground bed that a larger one. Conversely, if you use 60 grams of coffee for 32 fl oz of water you will want to run a bit coarser - can't do this with the blade or the cheaper crush burr grinders - conicals are better than flats too.
The exact fine or coarse grind you need is based on the drip through rate of your coffee maker - 5 to 6 minutes is a common time measure to aim for. Grind finer if it flows too fast, grind coarser if it flows into the carafe too slow. Doing this will allow you to locate the sweet spot for your grinder and coffee maker combination.