Makita BTW121 Instruction Manual page 7

Dial setting and function (Fig. 7)
Bolt fastening
Dial setting
01 – 98
99
00
Temporary bolt fastening and loosening
By using the B or C on the left dial in combination with one of the digits (from 0 to 9) on the right-hand dial, you can do
temporary bolt fastening or bolt loosening.
Dial setting
B [*]
Select dial 0 – 9 for B [*]
C [*]
Select dial 0 – 9 for C [*]
Operation (Fig. 8 & 9)
[*1] Presetting number of impacts is impossible for more
than 200 impacts (4 seconds).
[*2] Fastening time includes when you pull the trigger
completely.
CAUTION:
• Hold the tool firmly and place the socket over the bolt or
nut. Turn the tool on and fasten for the proper fastening
time and number of impacts (dial setting).
• Always insert the battery cartridge all the way until it
locks in place. If you can see the red part on the upper
side of the button, it is not locked completely. Insert it
fully until the red part cannot be seen. If not, it may
accidentally fall out of the tool, causing injury to you or
someone around you.
• If the tool is operated continuously until the battery car-
tridge has discharged, allow the tool to rest for 15 min-
utes before proceeding with a fresh battery.
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, fastening time and number of the impacts (dial
setting) is shown in the figures.
NOTE:
• Hold the tool pointed straight at the bolt or nut without
applying excessive pressure on the tool.
• When fastening screw M8 or smaller, carefully adjust
pressure on the switch trigger so that the screw is not
damaged.
Clockwise
Tool stops after the twice
the set number of impacts
is reached. See the next
section for the appropriate
fastening torque.
Pull the trigger to start the tool; release it to stop.
No rotation even with trig-
ger pulled.
Clockwise
After catching the first
impact, tool stops [*] x 0.1
seconds later.
Pull the trigger to start the
tool; release it to stop.
Counterclockwise
Pull the trigger to start the
tool; release it to stop.
Pull the trigger to start the
tool; release it to stop.
Counterclockwise
Pull the trigger to start the
tool; release it to stop.
After stopping to impact,
tool stops [*] x 0.1 seconds
later.
• Excessive fastening torque may damage the bolt or
nut. Before starting your job, always perform a test
operation to verify the adequate fastening speed, time
and number of impacts (dial setting) for your bolt or nut.
Especially for the bolt other than M8, perform the above
test operation to prevent the trouble on socket or bolt,
etc.
The fastening torque is affected by a wide variety of fac-
tors including the following. After fastening, always check
the torque with a torque wrench.
1. When the battery cartridge is discharged almost
completely, 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 the 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
somewhat 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 hold-
ing the tool and the tool speed will affect the torque.
Application
Bolt fastening while con-
trolling the number of
impacts.
Bolt fastening without con-
trolling the number of
impacts; or when fasten-
ing with more than 200
impacts (over 4 sec.)
—
Application
For temporary bolt fastening.
To loosen bolts.
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