ICFR – Chainsaw Safety and Operating Handbook
23
Directional notch
The directional notch is important as it:
•
Controls the felling direction.
•
Allows the tree to fall freely in the desired
direction.
•
Minimises splitting.
The top cut is made first at approximately a 45° angle
and for between 1/3 and 1/4 of the tree’s diameter. The
notch must accurately face the desired felling direction.
The bottom cut must be made level to meet the top cut
to form a clear, uniform “V” right across the diameter
of the tree once the cut section is removed.
Figure 13: Standard technique
Hinge
As the felling cut is brought towards the directional
notch leave a sufficient hinge uncut (approximately
1/10
of the tree’s diameter). The hinge:
•
Acts as a hinge and controls the felling direction.
•
Prevents the tree from twisting or bending
sideways when falling.
•
Prevents the tree from falling backwards.
•
Controls the speed of the fall.
The felling cut
The felling cut removes the wood from the back of
the tree to leave the hinge and allows the tree to fall.
10.11
f
elling
techniqueS
Once the preparation for felling has been completed the
operator is ready to make the first cut to fell the tree.
Only felling techniques that have been assessed as
being safe may be used. Techniques used will depend
on the characteristics of the trees to be felled and
the felling direction required. Modify the standard
technique if the trees:
•
Have a one-sided crown or a significant lean.
•
Are leaning in a direction opposite to the desired
felling direction.
•
Are leaning at a sharp angle towards the desired
felling direction.
•
Have a diameter that is more than the effective
length of the guide bar.
•
Are dead or have symptoms of rot.
•
Are prone to splitting.
Use the appropriate specialised felling technique in
these instances by adapting the depth of the notch, the
shape of the hinge and by using felling aids.
10.11.1
S
tAndArd
technique
The standard technique is used when the tree diameter
is not more than the guide bar length and the tree has
no significant lean.
Before commencing with the directional notch
(this
is applicable for other techniques and will not
be stated again)
, reduce buttresses as required to
achieve a more or less cylindrical tree-base to facilitate
directional felling. If the tree has large buttresses,
cut into the largest buttress vertically first, then
horizontally and remove the resultant piece of wood.
Figure 12: Reducing a buttress
