Makita BTW253 Owners Manual - Page 6

Fastening torque Proper fastening torque OPERATION CAUTION: • 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. Hold the tool firmly and place the socket over the bolt or nut. Turn the tool on and fasten for the proper fastening time. High tensile bolt N.m (ft.lbs) 140 (101) 120 (87) 100 (72) 80 (58) 60 (43) 40 (29) 20 (14) 0 M12(1/2") M12(1/2") M10(3/8") M8(5/16") M10(3/8") M8(5/16") 1.0 2.0 3.0 4.0 5.0 (S) Fastening time 008670 008666 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 fastening time is shown in the figures. Fastening torque Proper fastening torque Standard bolt N.m 140 (ft.lbs) (101) 120 (87) 100 (72) 80 (58) 60 (43) 40 (29) 20 (14) M14(9/16") M12(1/2") M14(9/16") M10(3/8") M12(1/2") M10(3/8") 008669 0 1.0 2.0 3.0 (S) Fastening time NOTE: • Hold the tool pointed straight at the bolt or nut. • 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. • If the tool is operated continuously until the battery cartridge has discharged, allow the tool to rest for 15 minutes before proceeding with a fresh battery cartridge. 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 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 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. 6