It is recommended that recalibration of the rolling straight edge by the manufacturer be carried out in the following instances:

At the start of a contractor testing programme

At intervals of 6 months or on completion of 30 km of testing, whichever occurs first

If the rolling straight edge fails to give correct reading during the user calibration check

If it is suspected that the equipment is not functioning correctly

General care

It is absolutely essential that the wheels are kept clean and free of tar, chippings, etc. Failure to clean the wheels after use will lead to inaccurate results.  In addition, recalibration cannot be carried out with wheels in poor condition.


DO clean wheels using Lamp Oil or similar paraffin-based solvent and a suitable cloth.


DO NOT use any solvent likely to attack rubber and/or plastic.


DO NOT lift assembled straight edge bodily off the ground.


ALWAYS roll sections together and apart on a smooth surface.


DO NOT use excessive force when clamping sections together.


NEVER push the straightedge at speed over badly rolled surfaces.


NEVER tow the straightedge behind a vehicle.


NEVER drag the straightedge sideways when turning round – roll the sections apart and lift them clear of the ground to turn them.