Starting Operation - Bosch GNF 20 CA Professional Manual Original

OBJ_BUCH-126-002.book Page 20 Wednesday, February 19, 2014 1:49 PM
20 | English
– Only use vacuum hoses as intended for by Bosch. Do not
manipulate the vacuum hose. When rocks or chunks of
stone/masonry are drawn into the vacuum hose, cease
work and clean the vacuum hose immediately. Prevent the
vacuum hose from being bent or creased.
– Use the wall chaser only according to its intended use.
– Only use tools that are in perfect condition. Decrease in
work progress is noticeable whilst using worn tools.
– Observe the general requirements for construction sites.
– Provide for good ventilation.
– Ensure that the working range/area is free of obstructions.
For longer slots, the vacuum cleaner must be guided along
in time, without obstructions in the path.
– Wear hearing protection, protective goggles, dust mask
and gloves as required. As dust mask, use at least a parti-
cle-filtering class FFP 2 half-mask.
– Use a suitable vacuum cleaner for cleaning the workplace.
Prevent settled dust from being swirled up by sweeping.
Mounting Diamond Cutting Discs
 Before any work on the machine itself, pull the mains
plug.
 When mounting and replacing diamond cutting discs, it
is recommended to wear protective gloves.
 Diamond cutting discs become very hot during opera-
tion; do not touch them until they have cooled down.
 Use only diamond-tipped cutting discs. Segmented dia-
mond wheels may only have negative cutting angles
and slots between the segments to a maximum of
10 mm.
Swivelling Out the Cutting Unit
For a tool change, the cutting unit must be swivelled out com-
pletely. Place the machine on a firm surface. Turn the release
lock 2 in anticlockwise direction, using e. g. the spanner end
of the two-pin spanner 21.
 This releases the cutting unit and immediately swivels
it upwards by means of resiliance.
Dismounting the Clamping Assembly (see figure A)
Press the spindle lock button 9 to lock the grinding spindle.
 Actuate the spindle lock button only when the grinder
spindle is at a standstill. Otherwise, the machine may be-
come damaged.
Loosen the clamping nut 20 with the two-pin spanner 21 and
unscrew the clamping nut 20. Remove the spacer discs 19
and the mounting flange 17.
Clean the grinder spindle 16 and all parts to be mounted.
Determining the Slot Width
The slot width results from the amount of spacer discs 19 be-
tween the two diamond cutting discs 18 and the cutting width
of the diamond cutting discs.
The slot width is calculated as follows:
Slot width = Thickness of the spacer discs + width of the dia-
mond cutting discs.
The allowable slot width is shown in the section "Technical
Data".
3 609 929 C89 | (19.2.14)
The machine can be operated with one or two diamond cut-
ting discs.
Mounting the Clamping Assembly (see figure A)
Set the mounting flange 17 onto the grinder spindle 16. The
mounting flange with its driving feature must be properly
seated on the grinding spindle.
Place the diamond cutting disc 18 and the spacer discs 19 on
the mounting flange 17.
 Regardless of the requested slot width, all spacer discs
19 provided must always be mounted. Otherwise, the di-
amond cutting disc 18 can become loose during operation
and lead to injuries.
Amount of required spacer discs:
GNF 20 CA: 5 pce., each 4 mm thick
GNF 35 CA: 3 pce., each 4 mm thick and 4 pce., each 6 mm
thick.
At least one spacer disc 19 must be mounted between two di-
amond cutting discs 18.
When mounting the diamond cutting discs, ensure that the di-
rection-of-rotation arrows on the diamond cutting discs
match with the rotation rotation direction of the machine (see
direction-of-rotation arrow on the gear case).
Press the spindle lock button 9 to lock the grinding spindle.
Screw on the clamping nut 20 and tighten it with the two-pin
spanner 21.
Swivel the cutting unit back again. Check the locking system
of the cutting unit by pulling the handle.
When working with 2 diamond cutting discs 18, always re-
place them in pairs.
See graphics page for the mounting sequence.
Operation
Pre-selecting the Cutting Depth
 The cutting depth may only be pre-selected when the
machine is switched off.
The requested cutting depth can be pre-selected with the
depth stop 6.
Press the button for depth stop adjustment 5 and push the
depth stop 6 to the requested cutting depth on the cutting-
depth scale 4. Release button 5 again.
Ensure that the depth stop 6 is engaged again.

Starting Operation

 Observe correct mains voltage! The voltage of the pow-
er source must agree with the voltage specified on the
nameplate of the machine. Power tools marked with
230 V can also be operated with 220 V.
Switching On and Off
 Before starting the machine, check if the cutting unit
has engaged in the upper position. Otherwise the dia-
mond cutting discs can touch the workpiece, resulting in
possible loss of control over the power tool when switching
on.
Bosch Power Tools