Eccentricity Measuring Instruments
Bench centers are instruments used to measure eccentricity. Level of eccentricity is also called eccentricity ratio, and when the center of gravity and center of rigidity match, eccentricity is displayed as being 0. Contrarily, the more the center of gravity and center of rigidity differ, the higher the eccentricity ratio is. With general bench centers, shaft bend and circular pitch run out of gears can be measured. The workpiece to be measured is held at both centers and slowly rotated, and eccentricity is read on a dial gauge. There are highly accurate bench centers with which precision measuring is possible, and they can be placed against cylindrically-shaped objects to measure eccentricity of external shape or inner diameter, radial runout, or small objects. There are various types of bench centers from small and compact ones to large vertical ones, so they are selected according to the application they are used for.