Makita DHP446 Manuel D'instructions page 8

Hold the tool firmly with one hand on the grip and the
other hand on the bottom of the battery cartridge to
control the twisting action.
Hammer drilling operation
CAUTION:
• There is a tremendous and sudden twisting force
exerted on the tool/bit at the time of hole break-
through, when the hole becomes clogged with chips
and particles, or when striking reinforcing rods
embedded in the concrete.
First, turn the action mode changing ring so that the arrow
on the tool body points to the
ring can be aligned in any torque levels for this operation.
Be sure to use a tungsten-carbide tipped bit.
Position the bit at the desired location for the hole, then
pull the switch 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 the bit partially from the hole. By
repeating this several times, the hole will be cleaned out
and normal drilling may be resumed.
Blow-out bulb (Optional accessory)
(Fig. 11)
After drilling the hole, use the blow-out bulb to clean the
dust out of the hole.
Screwdriving operation (Fig. 12)
First, turn the action mode changing ring so that the arrow
on the tool body points to the
adjusting ring to the proper torque level for your work.
Then proceed as follows.
Place the point of the driver bit in the screw head and
apply pressure to the tool. Start the tool slowly and then
increase the speed gradually. Release the switch trigger
as soon as the clutch cuts in.
CAUTION:
• Make sure that the driver bit is inserted straight in the
screw head, or the screw and/or bit may be damaged.
NOTE:
• When driving wood screws, predrill pilot holes to make
driving easier and to prevent splitting of the workpiece.
See the chart.
Nominal diameter of wood
screw
(mm)
3.1
3.5
3.8
4.5
4.8
5.1
5.5
5.8
6.1
006421
8
marking. The adjusting
marking. Adjust the
Recommended size of pilot
hole
(mm)
2.0 - 2.2
2.2 - 2.5
2.5 - 2.8
2.9 - 3.2
3.1 - 3.4
3.3 - 3.6
3.7 - 3.9
4.0 - 4.2
4.2 - 4.4
Drilling operation
First, turn the adjusting ring so that the pointer points to
the marking. Then proceed as follows.
CAUTION:
• Pressing excessively on the tool will not speed up the
drilling. In fact, this excessive pressure will only serve
to damage the tip of your bit, decrease the tool
performance and shorten the service life of the tool.
• There is a tremendous force exerted on the tool/bit at
the time of hole break through. Hold the tool firmly and
exert care when the bit begins to break through the
workpiece.
• A stuck bit can be removed simply by setting the
reversing switch to reverse rotation in order to back
out. However, the tool may back out abruptly if you do
not hold it firmly.
• Always secure small workpieces in a vise or with a
similar hold-down device.
• If the tool is operated continuously until the battery
cartridge has discharged, allow the tool to rest for
15 minutes before proceeding with a fresh battery.
Drilling in wood
When drilling in wood, the best results are obtained with
wood drills equipped with a guide screw. The guide screw
makes drilling easier by pulling the bit into the workpiece.
Drilling in metal
To prevent the bit from slipping when starting to make a
hole, make an indentation with a center-punch and
hammer at the point to be drilled. Place the point of the bit
in the indentation and start drilling.
Use a cutting lubricant when drilling metals. The
exceptions are iron and brass which should be drilled dry.
MAINTENANCE
CAUTION:
• Always be sure that the tool is switched off and the
battery cartridge is removed before attempting to
perform inspection or maintenance.
• Never use gasoline, benzine, thinner, alcohol or the
like. Discoloration, deformation or cracks may result.
Replacing the carbon brushes (Fig. 13)
Replace when they wear down to the limit mark. Keep the
carbon brushes clean and free to slip in the holders. Both
carbon brushes should be replaced at the same time. Use
only identical carbon brushes.
Use a screwdriver to remove two screws then remove the
rear cover. (Fig. 14)
Raise the arm part of the spring and then place it in the
recessed part of the housing with a slotted bit screwdriver
with a slender shaft or the like. (Fig. 15)
Use pliers to remove the carbon brush caps of the carbon
brushes. Take out the worn carbon brushes, insert the
new ones and replace the carbon brush caps in reverse.
(Fig. 16)
Make sure that the carbon brush caps have fit into the
holes in brush holders securely. (Fig. 17)
Reinstall the rear cover and tighten two screws securely.
To maintain product SAFETY and RELIABILITY, repairs,
any other maintenance or adjustment should be