![background image](http://html1.mh-extra.com/html/makita/btw070z/btw070z_instruction-manual_4203384009.webp)
9
The proper fastening torque may differ depending upon the
kind or size of the bolt, the material of the workpiece to be
fastened, etc. The relation between fastening torque and fas-
tening time is shown in the figures.
NOTE:
•
When fastening screw M8 (5/16”) or smaller, carefully
adjust pressure on the switch trigger so that the screw is
not damaged.
•
Hold the tool pointed straight at the bolt or nut without
applying excessive pressure on the tool.
•
Excessive fastening torque may damage the bolt/nut or
socket. Before starting your job, always perform a test
operation to determine the proper fastening time for your
bolt or nut. Especially for the bolt smaller than M8 (5/
16”), perform the above test operation to prevent the
trouble on socket or bolt, etc.
The fastening torque is affected by a wide variety of factors
including the following. After fastening, always check the
torque with a torque wrench.
1. When the battery cartridge is discharged almost com-
pletely, voltage will drop and the fastening torque will be
reduced.
2. Socket
•
Failure to use the correct size socket will cause a
reduction in the fastening torque.
•
A worn socket (wear on the hex end or square end)
will cause a reduction in the fastening torque.
3. Bolt
•
Even though the torque coefficient and the class of
bolt are the same, the proper fastening torque will
differ according to the diameter of bolt.
•
Even though the diameters of bolts are the same, the
proper fastening torque will differ according to the
torque coefficient, the class of bolt and the bolt
length.
4. The use of the universal joint or the extension bar some-
what reduces the fastening force of the impact wrench.
Compensate by fastening for a longer period of time.
5. Type of materials to be fastened, the manner of holding
the tool and the tool speed will affect the torque.
M8 (5/16”)
M6 (1/4”)
0.5
40
(29)
30
(21)
20
(14)
10
(7)
0
1.0
(S)
25
(13)
50
(25)
*1
(*2)
N·m
(ft·lbs)
(M8)
(M10)
(M6)
M10 (3/8”)
Standard
bolt
*1 Number of impacts
*2 Dial setting
001274
M8 (5/16”)
1.0
40
(29)
30
(21)
20
(14)
10
(7)
0
2.0
50
(25)
100
(50)
3.0
150
(75)
N·m (ft·lbs)
(S)
*1
(*2)
(M8)
(M6)
50
(36)
60
(43)
M10 (3/8”)
(M10)
M6 (1/4”)
High tensile
bolt
*1 Number of impacts
*2 Dial setting
001275