US Patent 7121932 Portable drill sharpener

A portable drill sharpener includes a casing, a sand-wheel, a positioning device, a first grinding unit and a second grinding unit, a holding member for positioning a drill to be ground, a first adjustment unit and a second adjustment unit respectively connected to the first and second grinding units. Each of the first and second adjustment unit includes a guide rail and a sliding frame is movably mounted on the guide rail. The fist and second grinding units have at least one axle along which the first and second grinding units are adjusted.