These are all considered rotary tools, but an inventor named A.J. A motor produces a variable rate of spin, and a specialized blade or bit performs a task, whether it be slicing through a piece of wood, boring a hole in sheet metal, or grinding down a burr. Many common power tools, such as a circular saw, drill, or grinding wheel, would fit the broad definition of a rotary tool. Circular saws and grinding wheels are also rotary tools, but not nearly as versatile as the multi-purpose Dremel.
