Bosch GRL 300 HV Professional User Manual

Page 25

English | 25

Bosch Power Tools

1 619 929 J21 | (21.6.11)

Levelling Accuracy of the Rotational Laser Level

Influences on Accuracy
The ambient temperature has the greatest influence. Espe-

cially temperature differences occurring from the ground up-

ward can divert the laser beam.
The deviations play a role in excess of approx. 20 m measur-

ing distance and can easily reach two to four times the devia-

tion at 100 m.
Because the largest difference in temperature layers is close

to the ground, the measuring tool should always be mounted

on a tripod when measuring distances exceeding 20 m. If pos-

sible, also set up the measuring tool in the centre of the work

area.
Accuracy Check of the Measuring Tool
Apart from exterior influences, device-specific influences

(such as heavy impact or falling down) can lead to deviations.

Therefore, check the accuracy of the measuring tool each

time before starting your work.
For the accuracy check, an unobstructed measuring distance

of 20 m on firm ground between two walls A and B is required.

With the measuring tool in the horizontal position, a transit

measurement is to be carried out across both axes X and Y

(both positive and negative) (altogether 4 complete measure-

ments).
– Mount the measuring tool in the horizontal position onto a

tripod 37 (accessory) or place it on a firm and level surface

near wall A. Switch the measuring tool on.

– After levelling, direct the laser beam in point operation on-

to the close wall A. Mark the centre point of the laser beam

on the wall (point I).

– Turn the measuring tool around by 180°, allow it to level in

and mark the centre point of the laser beam on the oppo-

site wall B (point II).

– Without turning the measuring tool, position it close to wall

B. Switch the measuring tool on and allow it to level in.

– Align the height of the measuring tool (using the tripod or

by underlaying, if required) in such a manner that the cen-

tre point of the laser beam is projected exactly against the

previously marked point II on wall B.

– Rotate the measuring tool by 180° without changing the

height. Allow it to level in and mark the centre point of the

laser beam on wall A (point III). Take care that point III is

as vertical as possible above or below point I.

– The difference d of both marked points I and III on wall A

amounts to the actual deviation of the measuring tool for

the measured axis.

Repeat the measuring procedure for the other three axes. For

this, turn the measuring tool prior to each measuring proce-

dure by 90°.
On the measuring section of 2 x 20 m = 40 m, the maximum

allowable deviation is:

40 m x ±0.1 mm/m = ±4 mm.

Consequently, the difference d between points I and III for

each of the four individual measurements may not exceed

4 mm max.
If the measuring tool should exceed the maximum deviation in

anyone of the four measuring procedures, have it checked at

a Bosch after-sales service agent.

Working Advice

Always use the centre of the laser point for marking.

The size of the laser point changes with the distance.

Laser Viewing Glasses (Accessory)
The laser viewing glasses filter out ambient light. This en-

hances the laser visibility for the eye.
f

Do not use the laser viewing glasses as safety goggles.

The laser viewing glasses are used for improved visualisa-

tion of the laser beam, but they do not protect against laser

radiation.

20 m

180°

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