A reciprocating hermetic compressor includes a cylinder block internal to a shell and carrying a cylinder and a radial bearing hub; a crankshaft vertically mounted in the radial bearing hub and carrying, inferiorly, a rotor of an electric motor and, superiorly, a support annular face and an eccentric portion. The holder and the connection head are attached to one or the other of a tie bar and a mirror support arm and rotatably secured together. The optimal mix of hierarchical levels and stages is determined such that the orthogonality checker achieves the minimized circuit area. Repeatability is insured by a normalization technique performed on the light source before each reading, and an alignment method operated on the reagent strip prior to emplacement on the apparatus. A pair of abrasive blades having V-shaped carbide cutting edges is mounted in the other of the slots to also form a V-shaped sharpening slot.