Maintenance - Makita HR3520B Instruction Manual

Installing or removing drill bit or other bits (bull
point, etc.) (Fig. 3 & 4)
Important:
Always be sure that the tool is switched off and
unplugged before installing or removing the bit.
Press in the tool retainer and turn it until the red dots on
the tool retainer and the tool holder are aligned. Release
the tool retainer. (Fig. 3)
Insert the bit into the tool holder as far as it will go. Press
in the tool retainer and turn it a full 180 degrees. Then
release it to secure the bit. (Fig. 4)
CAUTION:
Never use A-type shank bits. They can cause damage to
the tool.
To remove the bit, follow the installation procedure in
reserve.
Selecting action mode (Fig. 5)
(Not available for HR3520B)
Rotation with hammering:
For drilling in concrete, masonry, etc., rotate the change
k
lever to the 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. 6)
Loosen the wing bolt and adjust the depth gauge to the
desired depth. After adjusting, tighten the wing bolt.
Switch action (Fig. 7)
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. 8)
Install the center bit. (Fig. 9)
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. 10)
(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. 11)
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. 8)
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
k
change lever to the 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. 12 & 13)
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.
l
position. Then rest
l
position. Rest the core
5