Sharpening The Saw Chain; Cleaning The Guide Bar - Makita DUC303 Betriebsanleitung

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:
An excessive distance between
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.

Cleaning the guide bar

Chips and sawdust will build up in the guide bar groove.
They may clog the bar groove and impair the oil flow.
Clean out the chips and sawdust every time when you
sharpen or replace the saw chain.
► Fig.38
Cleaning the sprocket cover
Chips and saw dust will accumulate inside of the
sprocket cover. Remove the sprocket cover and saw
chain from the tool then clean the chips and saw dust.
► Fig.39
Cleaning the oil discharge hole
Small dust or particles may be built up in the oil discharge
hole during operation. These dust or particles may impair
the oil to flow and cause an insufficient lubrication on the
whole saw chain. When a poor chain oil delivery occurs at
the top of guide bar, clean the oil discharge hole as follows.
1.
Remove the sprocket cover and saw chain from
the tool.
2. Remove the small dust or particles using a slotted
screwdriver with a slender shaft or the like.
► Fig.40: 1. Slotted screwdriver 2. Oil discharge hole
3. Insert the battery cartridge into the tool. Pull the
switch trigger to flow built-up dust or particles off the oil
discharge hole by discharging chain oil.
4. Remove the battery cartridge from the tool.
Reinstall the sprocket cover and saw chain on the tool.
Replacing the sprocket
CAUTION:
A worn sprocket will damage a
new saw chain. Have the sprocket replaced in this
case.
Before fitting a new saw chain, check the condition of
the sprocket.
► Fig.41: 1. Sprocket 2. Areas to be worn out
Always fit a new locking ring when replacing the sprocket.
► Fig.42: 1. Locking ring 2. Sprocket
NOTICE:
Make sure that the sprocket is installed
as shown in the figure.
16 ENGLISH