Ryobi HD420 Manual Del Operador página 9

SELECTING HAMMER MODE OR DRILLING
MODE
See Figure 8, page 12.
To adjust for type of drilling, slide the selector on top of the
motor housing to hammer mode or drilling mode. The ham-
mer mode symbol is on the right and the drill bit symbol is
on the left.
NOTE: The hammer drill has not been designed for reverse
hammering.
Use carbide-tipped bits and select hammer mode when
drilling in hard materials such as brick, tile, concrete, etc.
Select normal drill mode when drilling with twist drills, hole
saws, etc., in soft materials.
DRILLING/DRIVING SCREWS
See Figure 9, page 12.
 Depress and release the switch trigger to be sure the drill
is in the OFF position before connecting it to a power
supply.
 Check the direction of rotation selector for the correct
setting (forward or reverse).
 Secure the material to be drilled in a vise or with clamps
to keep it from turning as the drill bit rotates.
 Plug the drill into power supply.
 Hold the drill firmly and place the bit at the point to be
drilled, or where the screw is to be driven.
WARNING:
Do not drive a screw where there is likely to be hidden
wiring behind the surface. Contact with a "live" wire will
make exposed metal parts of the tool "live" and possibly
shock the operator. If you must drive a screw where hid-
den wire may be present, always hold tool by insulated
gripping surfaces (handle) when performing the operation
to prevent a shock to the operator.
 Depress the switch trigger to start the drill.
 Move the drill bit into the workpiece, applying only enough
pressure to keep the bit cutting or driving the screw. Do
not force the drill or apply side pressure to elongate a
hole. Let the tool do the work.
WARNING:
When drilling, be prepared for binding at bit breakthrough.
When these situations occur, the drill has a tendency to
grab and kick in the opposite direction and could cause
loss of control when breaking through material. If not
prepared, this loss of control can result in possible seri-
ous injury.
OPERATION
 When drilling hard, smooth surfaces, use a center punch
to mark the desired hole location. This will prevent the
drill bit from slipping off-center as the hole is started.
 If the bit jams in the workpiece or if the drill stalls, stop
the tool immediately. Remove the bit from the workpiece
and determine the reason for jamming.
WOOD AND METAL DRILLING
For maximum performance, use high speed steel bits for
wood or metal drilling. Select drilling mode. Begin drilling
at a very low speed to prevent the bit from slipping off the
starting point.
Wood Drilling
 Increase the speed as the drill bit bites into the material.
 When drilling through holes, place a block of wood behind
the workpiece to prevent ragged or splintered edges on
the back side of the hole.
Metal and Steel Drilling
 Use a light oil on the drill bit to keep it from overheating.
The oil will prolong the life of the bit and increase the
drilling action.
 Maintain a speed and pressure which allows cutting
without overheating the bit. Applying too much pressure
will:
• Overheat the drill;
• Wear the bearings;
• Bend or burn bits; and
• Produce off-center or irregular-shaped holes.
 When drilling large holes in metal, start with a small bit,
then finish with a larger bit.
MASONRY DRILLING
For maximum performance, use carbide-tipped masonry
impact bits or designated hammer drill bits when drilling
holes in brick, tile, concrete, etc. Select hammer mode.
 Apply light pressure at medium speed for best results in
brick.
 Apply additional pressure for hard materials such as
concrete.
 When drilling holes in tile, practice on a scrap piece to
determine the best speed and pressure. Begin drilling at
a very low speed to prevent the bit from slipping off the
starting point.
9 — English