--- 9 ---
(5) Variation in amount of work possible per charge
Although the nominal chargeable capacity of the storage batteries used with the Model DS 9DVF is 1.4 Ah,
the actual capacity may vary within 10% of that value depending on the ambient temperature during use and
charging, and the number of times the batteries have been recharged. It should be noted that other factors
which may have a bearing on the amount of work possible per charge are the working conditions (ambient
temperature, type and moisture content of the workpiece, sharpness of the drill bit, etc.) and the operational
skill of the user.
(6) Precautions in the use of HSS drill bits
Although the Model DS 9DVF is designed for drilling capacities of 18 mm (23/32") in wood, and 12 mm
(15/32") in aluminum, and 10 mm (3/8") in mild steel, this capability is not as efficient as conventional electric
power tools. In particular, when drilling through aluminum material with a 12 mm (15/32") 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 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.
B. Suggestions and precautions for the efficient use of the charger and storage batteries
If the Type EB 914 storage batteries are exposed to direct sunlight for an extended period or if the tool has just
been operated for a long time, charging may not be possible if the temperature of a battery (type EB 914) is above
40 ˚C (104 ˚F). In such a case, the customer should be advised to place the battery in a shaded area with a good
airflow, and allow sufficient cooling before recharging. This phenomenon is common to all existing batteries and
chargers which employ temperature sensitive overcharge protection devices. The cooling time required before
recharging can be accomplished varies from a few minutes to about 30 minutes, depending on the load, duration
of use, and ambient temperature.
9. REFERENCE MATERIALS
9-1. Speed Control Mechanism
Spindle rotation speed of the Model DS 9DVF can be
controlled by simply varying the amount by which the
trigger switch is depressed. The relationship between the
amount the trigger switch is depressed (in millimeters) and
the rotation speed is illustrated in Fig. 3.
Note: The gradient and values illustrated in Fig. 3 are
intended for reference only, and will vary slightly
due to differences in the discharge condition of the
battery, the ambient temperature, and individual
speed-control element accuracy.
100
Rotation speed
60 5
(%)
12 8
0
2.2 0.5
6.5 0.5
8
+0.5
0
Amount trigger switch is depressed (mm)
Fig. 3
