Bosch GLM400C Operating/Safety Instructions Manual page 36

Accuracy Check and Calibration of the Grade Measurement
(see figure H)
Regularly check the accuracy of the grade measurement. This
is done by carrying out a reversal measurement. For this, place
the measuring tool on a table and measure the grade.
Turn the measuring tool by 180° and measure the grade again.
The difference of the indicated reading may not exceed by
more than 0.3° (max.).
In the event of larger deviations, you have to recalibrate the
measuring tool. For this, select
the display.
After severe temperature changes and impact, we recommend
an accuracy check and, if required, to recalibrate the measuring
tool. After a temperature change, the measuring tool must
acclimate for a while before calibrating.
Accuracy Check of the Distance Measurement
The accuracy of the measuring tool can be checked as follows:
– Select a permanently unchangeable measuring section
which is approx. 9.8 to 32 ft (3 to 10 m) long and which you
know the exact length of (e.g. room width, door opening).
The measurement should be performed under favorable
conditions, i.e. the measuring section should be indoors with
weak backlighting and the target area of the measurement
should be smooth and reflect well (e.g. a white-painted wall).
– Measure the distance 10 times in succession.
The deviation of the individual measurements from the
average value must not exceed ±.07 in (±2 mm) over the
entire measuring section in favorable conditions. Record the
measurements in order to be able to compare the accuracy
at a later date.
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11/3/17 1:09 PM