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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. Tightening torque
Refer to Fig. 15 for the tightening torque of bolts (according to size), under the conditions
shown in Fig. 16. Please use this example as a general reference, as tightening torque
will vary according to tightening conditions.
NOTE:
If a long striking time is used, screws will be strongly tightened. This may cause
the screw to break, or may damage the end of the bit.
If the unit is held at an angle to the screw being tightened, the head of the
screw may be damaged, or the specified torque may not be transmitted to the
screw. Always keep the unit and the screw being tightened in a straight line.
4. Use a tightening time suitable for the screw
The appropriate torque for a screw differs 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" (8 mm), there is a danger of the screw breaking, so please confirm the
tightening time and the tightening torque beforehand.
kgf·cm
N·m
(in-lbs)
Ordinary bolt
1000
100
(868)
800
80
(694)
600
60
(521)
400
40
(347)
200
20
(174)
0
0
0
1
2
Tightening time: sec
Bolt
Nut
18
9/16" × 1–15/16" (M14 × 50)
t=1" (25mm)
15/32" × 1–3/4" (M12 × 45)
t=1" (25mm)
3/8" × 1–3/6" (M10 × 30)
t=3/8" (10mm)
5/16" × 1–3/6" (M8 × 30)
t=3/8" (10mm)
(t: Steel plate thickness)
3
Washer
Steel plate
thickness t
Washer
kgf·cm
N·m
(in-lbs)
High tension bolt
1200
120
(1042)
1000
100
(868)
800
80
(694)
600
60
(521)
400
40
(347)
200
20
(174)
0
0
0
1
Tightening time: sec
Fig. 15
*The following bolt is used.
Ordinary bolt: Strength grade 4.8
High tension bolt: Hardness division 12.9
(
Explanation of strength grade:
4 — Yield point of bolt: 45,500 psi (32 kgf/mm
8 — Pulling strength of bolt: 56,900 psi (40 kgf/mm
Fig. 16
9/16" × 1–15/16" (M14 × 50)
t=1" (25mm)
15/32" × 1–3/4" (M12 × 45)
t=1" (25mm)
3/8" × 1–3/6" (M10 × 30)
t=3/8" (10mm)
5/16" × 1–3/6" (M8 × 30)
t=3/8" (10mm)
(t: Steel plate thickness)
2
3
2
)
)
2
)
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