However, a rotating shaft may be less tolerant of radial run-out since the centre of gravity is displaced by the amount of run-out.Īxial run-out is the result of a rotating component not being parallel with the axis, such as a drill chuck not holding the drill exactly in line with the axis. In general, cutting tools are more tolerant of radial run-out since the edges are parallel to the line of cutting tending to keep the tool tip aligned. This means that the rotating tool or shaft, instead of being centrally aligned, will rotate about a secondary axis. Radial run-out is the result of a rotating component running off centre, such as a ball bearing with an offset centre. At any point along a tool or shaft it is not possible to determine whether runout is axial or radial only by measuring along the axis can they be differentiated.Ībsolute alignment is impossible a degree of error will always be present. Runout will be present in any rotating system and, depending on the system, the different forms may either combine increasing total runout, or cancel reducing total runout. In addition, irregular run-out is the result of worn or rough bearings which can manifest itself as either axial or radial run-out. Axial run-out will vary according to how far from the base it is measured.

Axial run-out causes the tip of the tool (or shaft) to rotate off centre relative to the base. Axial run-out is caused by the tool or component being at an angle to the axis.Radial run-out will measure the same all along the main axis. the tool or component axis does not correspond with the main axis. Radial run-out is caused by the tool or component being rotated off centre, i.e.If a rotating component, such as a drill chuck, does not hold the drill centrally, then as it rotates the rotating drill will turn about a secondary axis. Run-out is dynamic and cannot be compensated. In the case of bearings, run-out will cause vibration of the machine and increased loads on the bearings.

For example when drilling, run-out will result in a larger hole than the drill's nominal diameter due to the drillīeing rotated eccentrically (off axis instead of in line). Run-out or runout is an inaccuracy of rotating mechanical systems, specifically that the tool or shaft does not rotate exactly in line with the main axis. For other uses, see Runout (disambiguation).

Another word for running out of time