Makita HR3850B, Instruction Manual

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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
reverse.
Selecting action mode (Fig. 5)
(Not available for HR3520B)
Rotation with hammering:
For drilling in concrete, masonry, etc., rotate the
change lever to the
position.
Hammering only:
For chipping, scaling or demolition operations, rotate
the 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 mecha-
nism, 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
trigger 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 bal-
ance 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
concrete, 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 position. Then
rest the core bit on the concrete and turn the tool
on. The core bit will come loose from the hammer-
ing 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 position. Rest the
core 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
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
procedures covered in When using the center bit.
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