Maintenance - Makita BUC250 Betriebsanleitung

CAUTION:
• If the upper edge of the bar is used for cutting, the
chain saw may be deflected in your direction if the
chain becomes trapped. For this reason, cut with the
lower edge, so that the saw will be deflected away from
your body. (Fig. 24)
Cut wood under tension on the pressure side (A) first.
Then make the final cut on the tension side (B). This pre-
vents the bar from becoming trapped. (Fig. 25)
Limbing
CAUTION:
• Limbing may only be performed by trained persons. A
hazard is presented by the risk of kick-back.
When limbing, support the chain saw on the trunk if pos-
sible. Do not cut with the tip of the bar, as this presents a
risk of kickback.
Pay particular attention to branches under tension. Do
not cut unsupported branches from below.
Do not stand on the felled trunk when limbing.
Burrowing and parallel-to-grain cuts
CAUTION:
• Burrowing and parallel-to-grain cuts may only be car-
ried out by persons with special training. The possibility
of kickback presents a risk of injury.
Perform parallel-to-grain cuts at as shallow an angle as
possible. Carry out the cut as carefully as possible, as
the serrated rail cannot be used. (Fig. 26)
Felling
CAUTION:
• Felling work may only be performed by trained persons.
The work is hazardous.
Observe local regulations if you wish to fell a tree.
- Before starting felling work, ensure that: (Fig. 27)
(1) Only persons involved in the felling operation are in
the vicinity;
(2) Any person involved has an unhindered path of
retreat through a range of approximately 45° either
side of the felling axis. Consider the additional risk
of tripping over electrical cables;
(3) The base of the trunk is free of foreign objects,
roots and branches;
(4) No persons or objects are present over a distance
of 2 1/2 tree lengths in the direction in which the
tree will fall.
- Consider the following with respect to each tree:
• Direction of lean;
• Loose or dry branches;
• Height of the tree;
• Natural overhang;
• Whether or not the tree is rotten.
- Consider the wind speed and direction. Do not carry
out felling work if the wind is gusting strongly.
- Trimming of root swellings: Begin with the largest swell-
ings. Make the vertical cut first, then the horizontal cut.
(Fig. 28)
- Cut a scarf: 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. Cut the 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.
- Cut any corrections to the scarf across its entire width.
- 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. Do not cut right through the fibers under any cir-
cumstances, as the tree will otherwise fall unchecked.
Insert wedges into the back cut in time. (Fig. 29)
- Only plastic or aluminum wedges may be used to keep
the back cut open. The use of iron wedges is prohib-
ited.
- Stand to the side of the falling tree. Keep an area clear
to the rear of the falling tree up to an angle of 45° either
side of the tree axis (refer to the "felling area" figure
(Fig. 27)). Pay attention to falling branches.
- An escape path should be planned and cleared as nec-
essary before cuts are started. The escape path should
extend back and diagonally to the rear of the expected
line of fall as illustrated in figure. (Fig. 30)
Carrying tool (Fig. 31)
Always remove the battery cartridge from the tool and
overlap the guide bar with the scabbard before carrying
the tool. Also cover the battery cartridge with the battery
cover.

MAINTENANCE

CAUTION:
• Always be sure that the tool is switched off and the bat-
tery cartridge is removed before attempting to perform
inspection or maintenance.
• Always wear gloves when performing any inspection or
maintenance.
• Never use gasoline, benzine, thinner, alcohol or the
like. Discoloration, deformation or cracks may result.
Sharpening the saw chain
CAUTION:
• Always remove the battery cartridge and wear safety
gloves when performing work on 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. The rea-
son for this behaviour is uneven sharpening of the saw
chain, or damage to one side only. (Fig. 32)
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.
- 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 cut-
ter is then the gauge dimension for all other cutters on
the saw chain.
- Guide the file as shown in the figure. (Fig. 33)
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