I've been using a Chemex for almost 20 years and the main variable ( assuming fresh beans and right grind) is water temp. 180-200 is ideal, just off boil will scald and below 180 extraction suffers. I can do it by timing by now but there are some day when I'm desperate that I just dump the water in right away. Fwiw my ratio is 50g to 3/4 of a Hario kettle. Works about 90 percent of the time.
8/22/16 at 1:40am