Hitachi DV18DL Instruction Manual - Page 19

(7) Precautions in the use of HSS drill bits For example, although the Model DV 18DL is designed for drilling capacities of 50 mm (2") in wood, and 13 mm (1/2") in aluminum and mild steel, this capability is not as efficient as conventional electric power tools. In particular, when drilling through aluminum material with a 13 mm (1/2") drill bit, the drill tends to become locked when the drill bit penetrates through the material. For this reason, the customer should be cautioned to reduce the thrust on the main body of the drill when drilling completely through the material to avoid locking the tool. Repeated locking of the drill causes excessive current flow from the batteries which not only decreases the amount of work possible per charge, but could also result in burning of the motor. (8) Securely tighten the sleeve of the keyless chuck. The keyless chuck may slip during operation if the shape of the drill bit shank is cylindrical depending on the surface conditions, materials, etc. Please instruct the customers to retighten the keyless chuck more securely if the keyless chuck slips during operation. The holding force of the keyless chuck is increased as the tightening force of the keyless chuck is increased. The Models DV 18DL and DV 14DL are equipped with the locking device to prevent loosening of the keyless chuck. The sleeve makes noise when tightening or loosening. This is because of the locking device and there is no problem. (9) Avoid continuous use. Although the Model DV 18DL can bear continuous operation under certain conditions, operating conditions are different depending on material of workpiece and sharpness of the drill bit in use. Please instruct the customers to avoid continuous use of the Models DV 18DVL and DV 14DL and take a pause about 15 minutes after a single charge operation as a guide. 9. REFERENCE MATERIALS 9-1. Speed Control Mechanism Spindle rotation speed of the Models DV 18DL and DV 14DL can be controlled by simply varying the amount by which the trigger switch is depresed. The relationship between the amount the trigger switch is depressed (in millimeters) and the rotation speed is illustrated in Fig. 2. NOTE: The gradient and values illustrated in Fig. 2 are intended for reference only, and will vary slightly due to differences in the discharge condition of the battery, the ambient temprature, and individual speed-control element accuracy. Rotation speed Depressed amount of the trigger switch (mm) Fig. 2 --- 16 ---