US Patent 7497649 Router

A fixed base router has a base supporting an upright wall. A motor based driver assembly is received in a cylindrical interior space delimited by the wall and movable along a spiral path. A read-out system includes a position sensor that detects and applies the displacement of the driver assembly along the spiral path to a processor based circuit, which in turn generates a signal indicating the displacement and a display device showing up the displacement for visual inspection. The read-out system allows for precise positioning the driver assembly and thus setting a cutting depth of a tool bit carried on and driven by the driver assembly so that adjustment of positioning of the tool bit is made simple, readable and precise.