Why you really need a bench grinder — HackSpace magazine
Posted about 5 years ago. Essentially, bench grinders are just tools for spinning grindstones, and these grindstones are for gently shaping metal. They're commonly used for getting blunt tools back to full sharpness, but they're not a onestopshop for instantly putting an edge on a tool. When using a cutting blade, the edge gradually dulls.