Hitachi P 20SB Handling Instructions Manual page 8

SHARPENIG THE CUTTER BLADES
Use of the optional accessory Blade Sharpening Ass'y is
recommended for convenience.
(1) Use of Blade Sharpening Ass'y
As shown in Fig. 26, two blades can be mounted
on the blade sharpening ass'y to ensure that the
blade tips are ground at equal angles. During
grinding, adjust the position of the cutter blades so
that their edges simultaneously contact the grinding
stone as shown in Fig. 27.
Cutter blade
(2) Cutter blade sharpening intervals:
Cutter blade sharpening intervals depend on the
type of wood being machined and the cutting depth.
However, sharpening should generally be effected
after each 500 meters of cutting operation.
(3) Grinding allowance of the cutter blades:
As illustrated in Fig. 28, a grinding allowance of
3.5 mm is provided for on the cutter blade. That
is, the cutter blade can be repeatedly sharpened
until its total height is reduced to 24.5 mm.
7
Machine screw
Fig. 26
Fig. 27
Grinding allowance 3.5
24.5 mm
Fig. 28
(4) Grinding Stone
When a water grinding stone is available, use it
after dipping it sufficiently in water since such a
grinding stone may be worn during grinding
procedure, flatten the upper surface of the grinding
stone as frequently as possible.
MAINTENANCE AND INSPECTION
1. Inspecting the cutter blades
Continued use of dull or damaged cutter blades will
result in reduced cutting efficiency and may cause
overloading of the motor. Sharpen or replace the
cutter blades as often as necessary.
2. Handling:
CAUTION
The front base, rear base, and cutting depth
control knob are precisely machined to obtain
specifically high precision. If these parts are
roughly handled or subjected to heavy mechanical
impact, it may cause deteriorated precision and
reduced cutting performance. These parts must
be handled with particular care.
3. Inspecting the mounting screws:
Regularly inspect all mounting screws and ensure
that they are properly tightened. Should any of the
screws be loose, retighten them immediately. Failure
to do so could result in serious hazard.
4. Inspecting the carbon brushes: (Fig. 29)
The motor employs carbon brushes which are
consumable parts. Since an excessively worn carbon
brush can result in motor trouble, replace the carbon
brushes with new ones having the same carbon
brush No. shown in the figure when it becomes
worn to or near the "wear limit". In addition, always
keep carbon brushes clean and ensure that they
slide freely within the brush holders.
Wear limit
21
5 mm
12 mm
5. Replacing carbon brushes:
Disassemble the brush caps with a slotted-head
screwdriver. The carbon brushes can then be easily
removed.
6. Maintenance of the motor:
The motor unit winding is the very "heart" of the
power tool.
Exercise due care to ensure the winding does not
become damaged and/or wet with oil or water.
7. Replacing supply cord
If the supply cord of Tool is damaged, the Tool
must be returned to Hitachi Authorized Service
Center for the cord to be replaced.
No. of carbon brush
Fig. 29