Operating Tips; Drill Bits; Drilling Wood - Bosch GSR12V-300FC Operating/Safety Instructions Manual

▶ Driving Nuts And Bolts
Variable speed control must be used with
caution for driving nuts and bolts with sock-
et set attach ments. The technique is to start
slowly, increasing speed as the nut or bolt
runs down. Set the nut or bolt snugly by
slowing the drill to a stop. If this procedure
is not followed, the tool will have a tendency
to torque or twist in your hands when the
nut or bolt seats.
▶ Drilling
You will extend the life of your bits and do
neater work if you always put the bit in con-
tact with the work before pulling the trigger.
During the oper a tion, hold the tool firmly
and exert light, steady pressure. Too much
pressure at low speed will stall the tool. Too
little pressure will keep the bit from cutting
and cause excess friction by sliding over the
surface. This can be damaging to both tool
and bit.
▶ Drilling With Variable Speed
The variable speed trigger allows you to
slowly increase RPM. By using a slow start-
ing speed, you are able to keep the bit from
"wander ing". You can increase the speed as
the bit "bites" into the work by squeezing
the trigger.
▶ Driving With Variable Speed
Variable speed drills will double as a power
screwdriver by using a screwdriver bit. Prior
to driving screws, pilot and clearance holes
should be drilled. Place the threaded 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. 13 will enable
you to fasten materials together using your
drill without stripping, splitting or separat-
ing 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.
2610051918.indd 15

Operating Tips

FASTENING WITH
SCREWS
1. Drill 2/3 diameter and
2/3 of screw length
for soft materials, full
length for hard mate-
rials.
Apply a slight even
pressure when driving
screws.
Second, unclamp the pieces and drill the
hole in the top piece of wood again to the
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.

▶ Drill Bits

Always inspect drill bits for excessive wear.
Use only bits that are sharp and in good con-
dition.
TWIST BITS: Available with straight and re-
duced 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 car-
bide tip bits.

▶ Drilling Wood

Be certain workpiece is clamped or an-
chored firm ly. Always apply pressure in
a straight line with the drill bit. Maintain
2. Drill same diame-
ter as screw shank.
3. C o u n t e r s i n k
same diameter as
screw head.
Screw
Top
Bottom
Fig. 13
15
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