Carrying Tool; Sharpening The Saw Chain - Makita DUC303 Manual De Instrucciones

When felling trees, follow the procedures below:
1. Cut a scarf as close to the ground as possible.
First make the horizontal cut to a depth of 1/5 -1/3 of the
trunk diameter. Do not make the scarf too large. Then
make the diagonal cut.
► Fig.30
NOTE: The scarf determines the direction in which
the tree will fall, and guides it. It is made on the side
towards which the tree is to fall.
2. Make the back cut a little higher than the base cut of
the scarf. The back cut must be exactly horizontal. Leave
approximately 1/10 of the trunk diameter between the back
cut and the scarf. The wood fibers in the uncut trunk portion
act as a hinge. Insert wedges into the back cut in time.
► Fig.31
Do not cut right through the fibers
WARNING:
under any circumstances. The tree will otherwise
fall unchecked.
NOTICE:
Only plastic or aluminum wedges may
be used to keep the back cut open. The use of
iron wedges is prohibited.

Carrying tool

Before carrying the tool, always apply the chain brake
and remove the battery cartridges from the tool. Then
attach the guide bar cover. Also cover the battery car-
tridge with the battery cover.
► Fig.32: 1. Guide bar cover 2. Battery cover
MAINTENANCE
CAUTION:
Always be sure that the tool is
switched off and the battery cartridge is removed
before attempting to perform inspection or
maintenance.
CAUTION:
Always wear gloves when perform-
ing any inspection or maintenance.
NOTICE:
Never use gasoline, benzine, thinner,
alcohol or the like. Discoloration, deformation or
cracks may result.

Sharpening the saw chain

Sharpen the saw chain when:
• Mealy sawdust is produced when damp wood is cut;
• The chain penetrates the wood with difficulty, even
when heavy pressure is applied;
• The cutting edge is obviously damaged;
• The saw pulls to the left or right in the wood.
(caused by uneven sharpening of the saw chain or
damage to one side only)
Sharpen the saw chain frequently but a little each time.
Two or three strokes with a file are usually sufficient for
routine resharpening. When the saw chain has been
resharpened several times, have it sharpened in our
authorized service center.
Sharpening criteria:
WARNING:
the cutting edge and depth gauge increases the
risk of kickback.
► Fig.33: 1. Cutter length 2. Distance between cutting
edge and depth gauge 3. Minimum cutter
length (3 mm)
— All cutter length must be equal. Different cutter
lengths prevent the saw chain from running
smoothly and may cause the saw chain to break.
— Do not sharpen the chain when the cutter length
has reached 3 mm or shorter. The chain must be
replaced with new one.
— The chip thickness is determined by the distance
between the depth gauge (round nose) and the
cutting edge.
— The best cutting results are obtained with following
distance between cutting edge and depth gauge.
• Chain blade 90PX : 0.65 mm (0.025")
• Chain blade 91PX : 0.65 mm (0.025")
► Fig.34
— The sharpening angle of 30° must be the same on
all cutters. Different cutter angles cause the chain
to run roughly and unevenly, accelerate wear, and
lead to chain breaks.
— Use a suitable round file so that the proper sharp-
ening angle is kept against the teeth.
• Chain blade 90PX : 55°
• Chain blade 91PX : 55°
File and file guiding
— Use a special round file (optional accessory) for
saw chains to sharpen the chain. Normal round
files are not suitable.
— Diameter of the round file for each saw chain is as
follows:
• Chain blade 90PX : 4.5 mm (3/16")
• Chain blade 91PX : 4.0 mm (5/32")
— The file should only engage the cutter on the for-
ward stroke. Lift the file off the cutter on the return
stroke.
— Sharpen the shortest cutter first. Then the length
of this shortest cutter becomes the standard for all
other cutters on the saw chain.
— Guide the file as shown in the figure.
► Fig.35: 1. File 2. Saw chain
— The file can be guided more easily if a file holder
(optional accessory) is employed. The file holder
has markings for the correct sharpening angle of
30° (align the markings parallel to the saw chain)
and limits the depth of penetration (to 4/5 of the
file diameter).
► Fig.36: 1. File holder
— After sharpening the chain, check the height of the
depth gauge using the chain gauge tool (optional
accessory).
► Fig.37
— Remove any projecting material, however small,
with a special flat file (optional accessory).
— Round off the front of the depth gauge again.
16 ENGLISH
An excessive distance between