There’s something about making a cup of coffee that riles people up. Somehow, each debate breeds its own sub-debates — brewer vs. pour over. Hario vs. Chemex. Medium grind vs. coarse grind, and so on.

Grinding, or abrasive machining, is the process of removing metal in the form of minute chips by the action of irregularly shaped abrasive particles. These particles may be in bonded wheels, coated ...