Bosch GLM Professional 50-27 CG Manual Original página 51

the laser viewing glasses (20) (accessory) and the laser target plate (19) (accessory) or
shade the target area.
Influences on the measurement result
Due to physical effects, the possibility of inaccurate measurements when measuring vari-
ous surfaces cannot be excluded. These include:
– Transparent surfaces (e.g. glass, water)
– Reflective surfaces (e.g. polished metal, glass)
– Porous surfaces (e.g. insulating materials)
– Structured surfaces (e.g. roughcast, natural stone).
If necessary, use the laser target plate (19) (accessory) on these surfaces.
Inaccurate measurements are also possible where the laser is pointed at target surfaces
diagonally.
Layers of air at different temperatures and indirectly received reflections can also influ-
ence the measured value.
Checking accuracy and calibrating the grade measurement (see figure M)
Regularly check the accuracy of the grade measurement. This is accomplished by means
of a reverse measurement. To do this, lay the measuring tool on a table and measure the
inclination. Turn the measuring tool by 180° and measure the inclination again. The dif-
ference between the displayed values must not exceed 0.3°.
In the event of larger deviations, you have to recalibrate the measuring tool. To do so, se-
lect in the settings. Follow the instructions on the display.
We recommend that you perform an accuracy check and if necessary a calibration of the
measuring tool after extreme temperature variations and after impact to the tool. After a
temperature variation, the measuring tool must adjust to the ambient temperature for a
while before calibration is performed.
Accuracy Check of the Distance Measurement
You can check the accuracy of the measuring tool as follows:
– Choose a measuring section of approx. 3–10 m in length that is permanently un-
changed, the exact length of which is known to you (e.g. room width, door opening).
The measurement should be taken under favourable conditions, i.e. the measuring
section should be indoors and the target surface for the measurement should be
smooth and reflect well.
– Measure the section ten times in succession.
The deviation of the individual measurements from the mean value must not exceed
±4 mm over the entire measuring section in favourable conditions. Record the measure-
ments in order to be able to compare the accuracy at a later date.
Bosch Power Tools
English | 51
1 609 92A 4ZJ | (14.10.2020)