Straightness is measured daily in many industries. For example, members, rollers, pipes, machine ends, machine runners and conveyors. Straightness measurements are also carried out for bearing positions, in, for example, diesel engines. Straightness is often a basic requirement in order for a machine to function correctly and/or produce fault-free parts.

Principle for straightness measurement

The basic principle for straightness measurement is that all measurement values will show the position of the detector unit relative to the laser beam. First, the beam is roughly aligned along the measurement object. The detector is then positioned on the selected measuring points and the values registered. According to the measurement, two of the measuring points are set to zero, and the other points are recalculated for this reference line. New measurement points can be added or removed. An offset value for all points can be added for automatic calculation of correct adjustment values.

Relative or absolute reference

​When the measured object is to be the reference (relative reference), the laser beam is levelled to the detector positioned at the two reference points. This levelling procedure is always carried out according to the same principle – zeroing the laser.
When using the horizontal reference (absolute reference), the laser beam is levelled according to the vials on the laser transmitter (D22). Then all detector values are shown in relation to the horizontal plane.

Straightness measurement with S and M units

It is also possible to perform a straightness measurement with S and M units (i.e. no separate laser transmitter is used). The S unit is used as a references transmitter and the M unit is used as a detector. However, it is not possible to use horizontal reference in this case.