Maintenance And Service; Rough Grinding; Cutting Metal; Cutting Stone - Bosch GWS Professional 20-180 Original Instructions Manual

OBJ_BUCH-721-005.book Page 12 Tuesday, August 30, 2011 2:58 PM
12 | English
Do not use damaged, out-of-centre or vibrating grind-
ing tools. Damaged grinding tools can burst and cause in-
juries.
Working Advice
Exercise caution when cutting slots in structural walls;
see Section "Information on Structures ".
Clamp the workpiece if it does not remain stationary
due to its own weight.
Do not strain the machine so heavily that it comes to a
standstill.
After heavily straining the power tool, continue to run
it at no-load for several minutes to cool down the acces-
sory.
Grinding and cutting discs become very hot while
working; do not touch until they have cooled.
Do not use the power tool with a cut-off stand.

Rough Grinding

Never use a cutting disc for roughing.
The best roughing results are achieved when setting the ma-
chine at an angle of 30° to 40°. Move the machine back and
forth with moderate pressure. In this manner, the workpiece
will not become too hot, does not discolour and no grooves
are formed.
Flap Disc
With the flap disc (accessory), curved surfaces and profiles
can be worked.
Flap discs have a considerably higher service life, lower noise
levels and lower sanding temperatures than conventional
sanding sheets.

Cutting Metal

For cutting with bonded abrasives, always use the pro-
tection guard for cutting 12.
When cutting, work with moderate feed, adapted to the mate-
rial being cut. Do not exert pressure onto the cutting disc, tilt
or oscillate the machine.
Do not reduce the speed of running down cutting discs by ap-
plying sideward pressure.
When cutting profiles and square bar, it is best to start at the
smallest cross section.
1 619 P09 125 | (30.8.11)

Cutting Stone

Provide for sufficient dust extraction when cutting
stone.
Wear a dust respirator.
The machine may be used only for dry cutting/grinding.
For cutting stone, it is best to use a diamond cutting disc.
When using the cutting guide with dust extraction protection
guard 22, the vacuum cleaner must be approved for vacuum-
ing masonry dust. Suitable vacuum cleaners are available
from Bosch.
For cutting expecially hard material, e. g., concrete with high
pebble content, the diamond cutting disc can overheat and
become damaged as a result. This is clearly indicated by cir-
cular sparking, rotating with the diamond cutting disc.
In this case, interrupt the cutting process and allow the dia-
mond cutting disc to cool by running the machine for a short
time at maximum speed with no load.
Noticeable decreasing work progress and circular sparking
are indications of a diamond cutting disc that has become
dull. Briefly cutting into abrasive material (e. g. lime-sand
brick) can resharpen the disc again.
Information on Structures
Slots in structural walls are subject to the Standard DIN 1053
Part 1, or country-specific regulations.
These regulations are to be observed under all circumstanc-
es. Before beginning work, consult the responsible structural
engineer, architect or the construction supervisor.
The machine must al-

Maintenance and Service

ways work in an up-
grinding motion. Other-
wise, the danger exists
Maintenance and Cleaning
of it being pushed un-
Before any work on the machine itself, pull the mains
controlled out of the
plug.
cut.
For safe and proper working, always keep the machine
and ventilation slots clean.
In extreme conditions, always use dust extraction as
far as possible. Blow out ventilation slots frequently
and install a residual current device (RCD). When work-
ing metals, conductive dust can settle in the interior of the
power tool. The total insulation of the power tool can be im-
paired.
Please store and handle the accessory(-ies) carefully.
Switch on the machine
and place the front part
of the cutting guide on
the workpiece. Slide the
machine with moderate
feed, adapted to the ma-
terial to be worked.
Bosch Power Tools