Bosch 1821 Instrucciones De Funcionamiento Y Seguridad página 14

BM 1609929Y07 10-10:BM 1609929Y07 10-10 1/18/11 10:06 AM Page 14
SELECTING GRINDING WHEELS
Before using a grinding
WARNING
wheel, be certain that its
maximum safe operating speed is not
exceeded by the nameplate speed of the
grinder. Do not exceed the recommended
wheel diameter.
DISC GRINDING WHEELS
Grinding wheels should be carefully selected in
order to use the grinder most efficiently.
Wheels vary in type of abrasive, bond,
hardness, grit size and structure. The correct
type of wheel to use is determined by the job.
Use disc grinding wheels for fast grinding of
structural steel, heavy weld beads, steel
casting, stainless steel and other ferrous
metals.
GRINDING TIPS
Efficient grinding is achieved by controlling the
pressure and keeping the angle between
wheel and workpiece at 10° to 15°. If the wheel
is flat, the tool is difficult to control. If the angle
is too steep, the pressure is concentrated on a
small area causing burning to the work
surface.
Excessive or sudden pres-
WARNING
sure on the wheel will slow
grinding action and put dangerous stresses on
the wheel.
When grinding with a new wheel be certain to
grind while pulling tool backwards until wheel
becomes rounded on its edge. New wheels
have sharp corners which tend to "bite" or cut
into workpiece when pushing forward.
CUTTING METAL
Using the optional type 1A wheel guard, it is
possible to perform limited cutting on small
stock such as metal tubes, piping or rebar.
When cutting, work with moderate feed,
adapted to the material being cut. Do not
exert side pressure onto the cutting disc, tilt
or oscillate the tool. When cutting profiles
and square bar, it is best to start at the
smallest cross section.
Grinding Operations
Always follow precautions for kickback.
Do not apply side pressure to cutting wheel
to reduce wheel speed.
The tool should always be used so that
sparks are directed away from user.
Operate the tool only with dust extraction and
additionally wear a dust protection mask. The
vacuum used for this application must be
approved for the extraction of masonry dust.
Bosch sells suitable vacuum cleaners.
WARNING
plate. The tool may be used only for dry
cutting. When cutting masonry use a dry
diamond wheel.
Always cut towards the dust extraction port
(Fig. 8).
FIG. 8
Turn the tool on and place the front part of the
cutting guide on the workpiece. Slide the tool
with moderate rate of feed, adapted to the
material to be cut.
When doing deep cuts, it is best to cut in
several shallow passes.
When cutting especially hard material, e. g.,
concrete with high pebble content, the dry
diamond wheel can overheat and become
damaged. This is clearly indicated by circular
sparking of the rotating dry diamond wheel.
In this case, interrupt the cutting process and
allow the dry diamond wheel to cool by running
the tool for a short time at maximum speed
with no load.
Noticeable decreasing work progress and
circular sparking are indications of a dry
diamond wheel that has become dull. Briefly
cutting into abrasive materials (e. g. brick) can
resharpen the wheel again.
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CUTTING MASONRY
When cutting masonry always
use dust extraction with foot