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Influences on Accuracy
The ambient temperature has the greatest
influence. Especially temperature differences
occurring from the ground upward can divert
the laser beam.
As thermal fluctuation is largest close to the
ground, the tool, if possible, should be mounted
on a commercially available tripod and placed in
the center of the working area.
Apart from exterior influences, device-specific
influences (such as heavy impact or falling
down) can lead to deviations. Therefore, check
the accuracy of the tool each time before
starting your work.
Should the tool exceed the maximum deviation
during one of the tests, see recalibration
procedure or have it recalibrated by a Bosch
after-sales service center.
Checking the Vertical Leveling Accuracy
For this check, a free measuring distance of
approx. 13 ft between floor and ceiling on a firm
surface is required.
– Draw a straight line on the ceiling.
– Mount the tool to the holder or a tripod.
Switch the tool on and rotate it in such a
manner that the bottom plumb beam can
be seen on the floor.
– Position the tool in such a manner that the
upper plumb beam points against the line
on the ceiling. Allow the tool to level in.
Mark the center of the upper laser point on
the line on the ceiling (point I). Also, mark
the center of the laser point on the floor
– Rotate the tool by 180°. Position it in such a
manner that the center of the bottom laser
point is directed on the already marked
point II and the upper laser point is directed
against the line on the ceiling. Allow the
tool to level in. Mark the center of the upper
laser point on the line on the ceiling (point
– The difference d of both marked points I
and III on the ceiling results in the actual
deviation of the tool to the plumb line.
On the measuring distance of 2 x 13 ft = 26 ft ,
the maximum allowable deviation is:
26 ft x ±0.0036 in/ft = ±3/16 in.
Thus, the difference d between points I and III
should not exceed 3/16 in (max.).
Recalibration Procedure (Up & Down
All tools are calibrated when processed
through the Bosch quality control program. This
process assures that the customer receives a
superior product which conforms to the Product
Specifications. Although tools have been
calibrated before reaching our customers, it
contains many precision machined parts which
may be affected if the instrument is subjected to
abuse. Therefore, if the device is ever dropped
In this case, bring the tool to the level position
and wait for the self-leveling to take place. As
soon as the tool is within the self-leveling range
of ±5° or ±3° respectively, all laser beams light
up continuously again.
In case of ground vibrations or position changes
during operation, the tool is automatically
leveled in again. To avoid errors by moving the
tool, check the position of the laser beams with
regard to the reference points upon re-leveling.
Always use the center of the laser point for
marking. The size of the laser point changes
with the distance.