Bosch GSR12V-300 Consignes D'utilisation/De Sécurité page 12

2610051568.qxp_GSR12V-300 12/19/18 1:15 PM Page 12
end of the screw in the pilot or clearance
hole and start driving the screw slowly,
increasing the speed as the screw runs
down. Set the screw snugly by slowing to a
stop.
▼ FASTENING WITH SCREWS
The procedure shown in Fig. 8 will enable
you to fasten materials together using your
drill without stripping, splitting or
separating the material.
First, clamp the pieces together and drill
the hole 2/3 the diameter of the screw. If
the material is soft, drill only 2/3 the
proper length. If it is hard, drill the entire
length.
Second, unclamp the pieces and drill the
hole in the top piece of wood again to the
FASTENING
WITH SCREWS
1. Drill 2/3 diameter and
2/3 of screw length for
soft materials, full
length for hard
materials.
Screw
Apply a slight
even pressure
when driving
screws.
same diameter as the shank of the screw.
Third, if flat head screw is used,
countersink the hole to make the screw
flush with the surface. Realign the holes on
the two pieces and apply even pressure
when driving the screw. The screw shank
clearance hole in the first piece allows the
screw head to pull the pieces tightly
together.
The adjustable screw drill accessory will do
all of these operations quickly and easily.
Screw drills are available for screw sizes
No. 6, 8, 10 and 12.
Operating Instructions
2. Drill same
diameter as
screw shank.
3. Countersink
same diameter
as screw head.
Adjustable
Screw
Drill
FIG. 8
▼ DRILL BITS
Always inspect drill bits for excessive wear.
Use only bits that are sharp and in good
condition.
TWIST BITS: Available with straight and
reduced shanks for wood and light duty
metal drilling. High speed bits cut faster
and last longer on hard ma terials.
CARBIDE TIPPED BITS: Used for drilling
stone, con crete, plaster, cement and other
unusually hard nonmetals. Use continuous
heavy feed pres sure when employing
carbide tip bits.
▼ DRILLING WOOD
Be certain workpiece is clamped or
anchored firm ly. Always apply pressure in a
straight line with the drill bit. Maintain
enough pressure to keep the drill "biting".
When drilling holes in wood, twist bits can
be used. Twist bits may overheat unless
pulled out frequently to clear chips from
flutes.
Use a "back-up" block of wood for work
that is likely to splinter, such as thin
materials.
You will drill a cleaner hole if you ease up
on the pressure just before the bit breaks
through the wood. Then complete the hole
Top
from the back side.
▼ DRILLING METAL
Bottom
There are two rules for drilling hard
materials. First, the harder the material, the
greater the pres sure you need to apply to
the tool. Second, the harder the material,
the slower the speed. Here are a couple of
tips for drilling in metal. Lubri cate the tip
of the bit occasionally with cutting oil
except when drilling soft metals such as
alu minum, cop per or cast iron. If the hole
to be drilled is fairly large, drill a smaller
hole first, then enlarge to the required size,
it's often faster in the long run. Main tain
enough pressure to assure that the bit does
not just spin in the hole. This will dull the
bit and greatly shorten its life.
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