Abstract: A process finishes the surface of rotationally symmetrical workpieces. The workpiece is pre-machined and hardened with a stock allowance and is then finished in two steps in a device in which it is clamped only once. The largest part of the stock allowance is first cut by a hard turning process and the residue is then ground down to the actual size of the workpiece to be manufactured. The device for performing this process includes a motor-driven workpiece spindle for receiving the workpiece having a spindle head. The workpiece spindle has at least one motor-driven grinding spindle adapted to accept a grinding tool. The grinding spindle generally is axially aligned with the workpiece spindle or the workpiece thereon. The workpiece spindle can be fitted with a lathe tool having a cutting edge for hard turning.

Abstract: An electric precipitator has a plurality of parallel, longitudinally straight and throughoing, and transversely spaced longitudinal main beams, respective parallel, planar, and transversely spaced longitudinal main plates suspended from the beams, a plurality of parallel and longitudinally spaced cross plates extending generally orthogonally between the main plates and defining corners therewith, and respective oblique webs in the corners and each extending at about 45.degree. from the respective cross plate to the respective main plate. Thus the plates and webs together define octagonal-section passages. Respective electrodes extend centrally in the cells and, due to the octagonal section of these cells, there are no dead corners and, in fact, charge concentration is more uniform than in the hexagonal-section systems.