Makita BUC121 Bedienungsanleitung Seite 12

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. The
reason for this behaviour is uneven sharpening of
the saw chain, or damage to one side only.
Sharpen the saw chain frequently, but remove only
a little material 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 a
MAKITA specialist repair shop.
File and file guiding
− Use a special round file (optional accessory) for
saw chains, with a diameter of 4 mm, to sharpen
the chain. Normal round files are not suitable.
Fig.20
− The file should only engage the material on the
forward stroke. Lift the file off the material on the
return stroke.
− Sharpen the shortest cutter first. The length of this
cutter is then the gauge dimension for all other
cutters on the saw chain.
− Guide the file as shown in the figure.
− The file can be guided more easily if a file holder
(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).
Guide the file as shown in the figure.
− After sharpening the chain, check the height of the
depth gauge using the chain gauge tool (optional
accessory).
Fig.21
− Remove any projecting material, however small,
with a special flat file (optional accessory).
− Round off the front of the depth gauge again.
− Wash away dust and particles from saw chain
after adjusting the height of depth gauge.
Cleaning guide bar
Fig.22
Chips and sawdust will build up in the guide bar groove,
clogging it and impairing oil flow. Always clean out the
chips and sawdust when sharpening or replacing the
saw chain.
Cleaning the oil filter at the oil discharge hole
Small dust or particles may be built up in the oil filter at
the oil discharge hole during operation.
Small dust or particles built up in the oil filter may impair
the oil discharge 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 filter as follows.
Remove the battery cartridge from the tool.
Remove the sprocket cover and saw chain from the tool.
(Refer to the section titled " Installing or removing saw
chain ".)
Fig.23
Remove the push nut using a slotted bit screwdriver
with a slender shaft or the like.
Fig.24
Take the filter out of the chain saw and remove small
dust or particles from it. When the filter is too dirty,
replace it with a new one.
Insert the battery cartridge into the tool.
Fig.25
Pull the switch trigger to flow built-up dust or particles
off the oil discharge hole by discharging chain oil.
Remove the battery cartridge from the tool.
Fig.26
Insert the cleaned oil filter into the oil discharge hole.
When the filter is too dirty, replace it with a new one.
Fig.27
Insert the push nut with its correct side facing up as
shown in the figure into the oil discharge hole to secure
the filter. When the filter cannot be secured with a
disfigured push nut, replace the push nut with a new
one.
Reinstall the sprocket cover and saw chain on the tool.
Replacing the sprocket
Before fitting a new saw chain, check the condition of
the sprocket.
Fig.28
CAUTION:
A worn sprocket will damage a new saw chain.
•
Have the sprocket replaced in this case. The
sprocket need to be installed so that it always
faces as shown in the figure.
Fig.29
Always fit a new locking ring when replacing the
sprocket.
Replacing carbon brushes
Fig.30
Remove and check the carbon brushes regularly.
Replace when they wear down to the limit mark. Keep
the carbon brushes clean and free to slip in the holders.
Both carbon brushes should be replaced at the same
time. Use only identical carbon brushes.
Use a screwdriver to remove the brush holder caps.
Take out the worn carbon brushes, insert the new ones
and secure the brush holder caps.
Fig.31
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