Abstract: An adapter for converting a right angle grinder into a random orbital sander which employs a sanding pad assembly, the right angle grinder having a threaded output shaft, the adapter including a cylindrical body having a bearing aperture on its front side and a threaded bore for screwing onto the threaded output shaft on its back side, the axis of the threaded bore corresponding to the axis of the cylindrical body; a bearing assembly fitted into the bearing aperture so that as to establish a second axis of rotation that is parallel to but offset from the axis of the cylindrical body; an attachment for attaching the sanding pad assembly to the bearing assembly so that the sanding pad assembly can rotate freely about the second axis; a counterweight mounted on the front side of the cylindrical body so as to be located relative to measurement along the cylindrical axis at a position that is between the center of mass of the bearing assembly and the sanding pad assembly when the sanding pad assembly is connected