2. Cautions on use of the speed control switch
This switch has a built-in, electronic circuit which
steplessly varies the rotation speed. Consequently,
when the switch trigger is pulled only slightly (low
speed rotation) and the motor is stopped while
continuously driving in screws, the components of
the electronic circuit parts may overheat and be
damaged.
3. Use a tightening time suitable for the screw
The appropriate torque for a screw di
ff
ers according
to the material and size of the screw, and the material
being screwed etc., so please use a tightening time
suitable for the screw. In particular, if a long tightening
time is used in the case of screws smaller than 5/16"
(M8), there is a danger of the screw breaking, so
please con
fi
rm the tightening time and the tightening
torque beforehand.
4. Work at a tightening torque suitable for the bolt under
impact
The optimum tightening torque for nuts or bolts
di
ff
ers with material and size of the nuts or bolts. An
excessively large tightening torque for a small bolt
may stretch or break the bolt. The tightening torque
increases in proportion to the operation time. Use the
correct operating time for the bolt.
5. Holding the tool
Hold the tool
fi
rmly with both hands. In this case hold
the tool in line with the screw or bolt.
It is not necessary to push the tool very hard. Hold the
tool with a force just su
ffi
cient to counteract the impact
force.
6. Con
fi
rm the tightening torque
The following factors contribute to a reduction of the
tightening torque. So con
fi
rm the actual tightening
torque needed by screwing up some bolts before the
job with a hand torque wrench. Factors a
ff
ecting the
tightening torque are as follows.
(1) Voltage
When the discharge margin is reached, voltage
decreases and tightening torque is lowered.
(2) Operating time
The tightening torque increases when the operating
time increases. But the tightening torque does not
increase above a certain value even if the tool is
driven for a long time.
(3) Diameter of bolt
The tightening torque di
ff
ers with the diameter of the
bolt. Generally a larger diameter bolt requires larger
tightening torque.
(4) Tightening conditions
The tightening torque di
ff
ers according to the torque
ratio; class, and length of bolts even when bolts with
the same size threads are used. The tightening torque
also di
ff
ers according to the condition of the surface of
workpiece through which the bolts are to be tightened.
When the bolt and nut turn together, torque is greatly
reduced.
(5) Tightening torque varies, depending on the battery’s
charge level.
19
English
000WH18DBDL2̲metabo.indb 19
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2020/11/06 10:24:38
2020/11/06 10:24:38
