Image Number 9 for United States Patent #4411105.
The drill grinder includes a drill bit holder mounted for movement about a swing axis provided by a rocker arm. The swing axis parallels the plane of the grinding wheel. An index ring mounted on the holder provides precise indexing of the drill bit. The extent of micrometric feed movement of the rocker arm is precisely marked so that such movement can be exactly duplicated as to all lip surfaces, thus achieving a symmetrically surfaced drill bit. These structures are integrated in a system that provides simple adjustment for drill bit size, clearance angle and contour control of lip surface.