Fig. 13 - Bosch 22612 Operating/Safety Instructions Manual

BM 2609140358 12-05
You will extend the life of your bits and do
neater work if you always put the bit in
contact with the work before pulling the
trigger. During the operation, 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.
DRIVING WITH VARIABLE SPEED
The technique is to start slowly, increasing
the speed as the screw runs down. Set the
screw snugly by slowing to a stop. Prior to
driving screws, pilot and clearance holes
should be drilled.
Always hold the machine straight on the bolt
to be tightened.
The best method to determine the right
impacting/tightening duration is by means of
a trial. For small screws, the right
impacting/tightening duration can be reached
in less then 0.5 Sec. Therefore, work with low
RPM and switch the machine off immediately
when the screw is tight and the impacting
sound can be heard.
For screwing larger, longer wood screws into
hard material, pre-drilling is the best method.
TIGHTENING TORQUE
The tightening torque depends on the
duration of the impacting/tightening action.
FASTENING WITH SCREWS
This procedure shown in (Fig. 13) will enable
you to fasten materials together with your tool
without stripping, splitting or separating the
material.
First, clamp the pieces together and drill the
first 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
second hole the same diameter as the screw
shank in the first or top piece of wood.
Third, if flat head screw is used, countersink
the hole to make the screw flush with the
surface. Then, simply apply even pressure
when driving the screw. The screw shank
12/6/05 3:28 PM
Operating Tips
Page 16
The largest tightening torque is achieved
after approx. 6 to 10 Sec. impacting/
tightening action.
The torque build-up depends on the
following factors:
• Hardness of the bolts/nuts.
• Type of washer (disk washer, spring
washer, seal).
• Hardness of the material to be joined.
• Lubricating effect at the surfaces of the
junction.
This leads to the following application cases:
Hard case: The joining of metal to metal with
a disk washer. The maximum torque is
reached after a relative short impacting/
tightening action.
Medium case: The joining of metal to metal
where spring ring washer, disk spring
washer, stud bolts or bolts/nuts with conical
seats are used.
Soft case: The joining of e.g. metal to wood
or insulation material.
For middle or soft joining cases, the
maximum tightening torque is less as for
hard cases. Therefore, a longer impacting/
tightening action is necessary to arrive at the
maximum tightening torque.
FASTENING
WITH SCREWS
1. Drill 2/3 diameter and
2/3 of screw length for
soft materials, full
length for hard
materials.
Apply a slight
even pressure
when driving
screws.
-16-
2. Drill same
diameter as
screw shank.
3. Countersink
same diameter
as screw head.
Screw

FIG. 13