Maintenance And Service; Maintenance And Cleaning - Bosch GBM 50-2 Professional Manual Original

– Metal workpieces should be centre-punched before being
drilled.
– Twist drill: For drilling diameters > 10 mm, pre-drill with a
small drilling diameter. This allows you to reduce the con-
tact pressure and puts less strain on the power tool.
– When drilling into metal, only use sharpened annular cut-
ters (brand accessories) that are in perfect condition.
– Turn the crank handle (4) to move the drill forwards.
– Select the speed that is appropriate to the specifications
of the tool
Note: When thread-cutting, the lowest speed setting
must be used.
Working with the Annular Cutter
– Only use annular cutters that are free of defects; ensure
that these are in perfect condition before each use. Do
not use any annular cutters that are damaged.
– Switch the power tool off immediately if the annular cut-
ter gets stuck.
– Protect the annular cutter. The tip of the annular cutter is
hard yet fragile.
The following measures will help to slow down the wear and
prevent breakage of annular cutters:
– When drilling in steel, ensure that there is enough coolant
available; use coolant for metal cutting.
– Make sure that the workpiece is level and clean to guaran-
tee the required magnet strength.
– Before drilling, ensure that all parts are properly at-
tached.
– At the start and end of the drilling procedure, the contact
pressure should be reduced by a third.
– If large quantities of metal chips accrue when drilling in
materials such as cast iron, copper die casting, etc., com-
pressed air can be used instead of coolant to assist in the
removal of metal chips.
Neutral Position of the Rotational Direction Switch
The power tool stops if the rotational direction switch (8) is
activated during drilling.
If the rotational direction switch is in the centre position, the
application tool can be rotated clockwise while the on/off
switch for the motor (9) is continuously pressed.
In this way, the thread-cutting process can be ended
smoothly.
Drilling
– Align the power tool by referring to the laser cross on the
workpiece.
– Switch the magnet on to fix the power tool to the work-
piece.
– Secure the power tool with the safety strap when drilling
into vertical or sloped surfaces, or working overhead.
– Set an appropriate speed.
– Switch on the power tool.
– To drill, turn the crank handle (4) with uniform feed until
the required drilling depth is reached.
Bosch Power Tools
– Once the required drilling depth has been reached, re-
tract the crank handle until the drive unit has returned to
its initial position.
– Switch off the power tool, loosen the safety strap if ne-
cessary and switch off the laser and magnet.
Transport
– Check that all application tools are firmly connected with
the power tool and that the drill core is no longer situated
in the application tool.
– Wind up the network cable completely and tie it together.
– Always use the transport handle (3) to lift and transport
the power tool.
– Never pull on the crank or the cable of the power tool in
order to move it.

Maintenance and service

Maintenance and Cleaning

Pull the plug out of the socket before carrying out any
u
work on the power tool.
To ensure safe and efficient operation, always keep
u
the power tool and the ventilation slots clean.
In order to avoid safety hazards, if the power supply cord
needs to be replaced, this must be done by Bosch or by an
after-sales service centre that is authorised to repair Bosch
power tools.
Replacing carbon brushes
Indicator for carbon brush change:
The indicator for changing the carbon brush (14) will start to
light up red approx. eight hours before the power tool auto-
matically switches off as a result of the carbon brushes wear-
ing out. You can continue to use the power tool until it
switches off.
The power tool should be sent to the Bosch after-sales ser-
vice. For addresses, see the section "After-Sales Service and
Application Service".
Never replace only a single carbon brush.
Note: Only use carbon brushes supplied by Bosch and inten-
ded specifically for your product.
– Unscrew the carbon brush cover (1) using a suitable
screwdriver.
– Replace the spring-loaded carbon brushes and screw the
cap back on again.
Adjusting the Guide Rail Gap (see figures E1 – E3)
If the power tool vibrates strongly when drilling or a gap is
visible on the guide rail, the width of the guide rail gap must
be adjusted. This prevents application tools from being
snapped off and avoids damage to the power tool.
– Pull the mains plugs out of the plug socket, remove ap-
plication tools and the coolant supply system and place
the power tool down on a firm, level and horizontal sur-
face.
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1 609 92A 4S6 | (10.05.2019)