Maintenance - Makita HR3520 Instruction Manual

Installing or removing drill bit or other bits
(bull point, etc.) (Fig. 3)
Important:
Always be sure that the tool is switched off and
unplugged before installing or removing the bit.
Pivot the tool retainer to the side. (If it is difficult to move
the tool retainer with your thumbs, tap it with a hammer.)
Insert the bit into the tool barrel as far as it will go. Return
the tool retainer to its original position to secure the bit.
To remove the bit, follow the installation procedure in
reverse.
Selecting action mode (Fig. 4)
(Not available for HR3520)
Rotation with hammering:
For drilling in concrete, masonry, etc., rotate the change
lever to the k position.
Hammering only:
For chipping, scaling or demolition operations, rotate the
l
change lever to the position.
CAUTION:
• Do not rotate the change lever when the tool is running
under load. The tool will be damaged.
• To avoid rapid wear on the mode change mechanism,
be sure that the change lever is always positively
located in one of the two action mode positions.
Adjusting depth of drilling (Fig. 5)
Loosen the wing bolt and adjust the depth gauge to the
desired depth. After adjusting, tighten the wing bolt.
Switch action (Fig. 6)
CAUTION:
• Before plugging in the tool, always check to see that
the switch trigger actuates properly and returns to the
"OFF" position when released.
• Do not tape, tie or otherwise secure the trigger in the
"ON" position.
To start the tool, simply pull the trigger. Release the trig-
ger to stop.
Hammer drilling operation
Position the bit at the location for the hole, then pull the
trigger.
Do not force the tool. Light pressure gives best results.
Keep the tool in position and prevent it from slipping away
from the hole.
Do not apply more pressure when the hole becomes
clogged with chips or particles. Instead, run the tool at an
idle, then remove from the hole. By repeating this several
times, the hole will be cleaned out.
CAUTION:
When the bit begins to break through concrete or if the
bit strikes reinforcing rods embedded in concrete, the tool
may react dangerously. Maintain good balance and safe
footing while holding the tool firmly with both hands to
prevent dangerous reaction.
Chipping / Scaling / Demolition
Hold the tool firmly with both hands. Turn the tool on and
apply slight pressure on the tool so that the tool will not
bounce around, uncontrolled. Pressing very hard on the
tool will not increase the efficiency.
Core bit (optional accessory)
When using the center bit
Screw the core bit on the adapter. Install the adapter with
the core bit in the tool in the same manner as a drill bit.
(Fig. 7)
Install the center bit. (Fig. 8)
Rest the core bit on the concrete and turn the tool on.
Once the core bit has cut a shallow groove into the con-
crete, remove the center bit. Then resume drilling.
To remove the core bit, follow the procedures (1) or (2).
(1) Rotate the change lever to the
the core bit on the concrete and turn the tool on. The
core bit will come loose from the hammering action.
(Fig. 9)
(2) Hold the adapter with the wrench, insert the rod
(optional accessory) into the hole in the core bit and
tap with a hammer to unscrew. (Fig. 10)
When not using the center bit
Screw the core bit on the adapter. Install the adapter with
the core bit in the tool in the same manner as a drill bit.
(Fig. 7)
Rotate the change lever to the
bit on the concrete and turn the tool on. Once the core bit
has cut a shallow groove into the concrete, rotate the
change lever to the k position and resume drilling.
NOTE:
No problem is caused even if the core bit unscrews
slightly during brief use since the core bit rotates in the
tightening direction.
To remove the core bit, follow the same removal proce-
dures covered in When using the center bit.

MAINTENANCE

CAUTION:
Always be sure that the tool is switched off and
unplugged before carrying out any work on the tool.
Replacement of carbon brushes (Fig. 11 & 12)
Whenever carbon brushes must be replaced, they cut out
the tool automatically. When this occurs, replace both
carbon brushes at the same time. Use only identical car-
bon brushes.
Lubrication (Fig. 13 & 14)
This tool requires no hourly or daily lubrication because it
has a grease-packed lubrication system. Lubricate the
tool every time the carbon brushes are replaced.
Run the tool for several minutes to warm it up. Switch off
and unplug the tool. Remove the crank cap using a Mak-
ita lock nut wrench 35 (optional accessory). Rest the tool
on the table with the bit end pointing upwards. This will
allow the old grease to collect inside the crank housing.
Wipe out the old grease inside and replace with a fresh
grease (60 g). Use only Makita genuine grease (optional
accessory). Filling with more than the specified amount
of grease (approx. 60 g) can cause faulty hammering
action or tool failure. Fill only with the specified amount of
grease. Reinstall the crank cap and tighten with the lock
nut wrench. Do not tighten the crank cap excessively. It is
made of resin and is subject to breakage.
To maintain product safety and reliability, repairs, mainte-
nance or adjustment should be carried out by a Makita
Authorized Service Center.
l
position. Then rest
l
position. Rest the core
5