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 
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. 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 ªOFFº position when released.
·Do not tape, tie or otherwise secure the trigger in the ªONº 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. 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 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. 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 
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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