Page 14 - Moving the Earth_ The Workbook of Excavation

LAND CLEARING AND CONTROLS

1.14 THE WORK

Cutting. If the trees are valuable and lumbermen will not clear them out in time, the contractor
may cut and stack them for future sale. This, as a logging proposition, is somewhat out of the field
of this book and will be considered very briefly.
Practically all wood cutting is now done with chain saws operated by one worker. Their con-
struction and operation are described in Chap. 21.
There are a number of sizes and models. Thick logs require long blades and increased power.
For any log thickness or blade length, increase in engine power means faster cutting, but also
more weight to handle.
Most experts recommend use of a bar long enough to cut the average size tree on the job in one
cut. Undergrowth should be roughly cleared around the tree before cutting it, to reduce danger to
workers and tangles with fallen trees.
A tree should be notched by a V cut up to one-third of trunk thickness, on the side toward
which it is expected to fall. The bottom cut of the notch should be made first and should be hori-
zontal, the other sloped down to meet it. See Fig. 1.6.
The tree is then cut through from the other side with a level cut 2 inches or more above the
floor of the notch.
If the saw bar is longer than the tree diameter, or a hand crosscut is used, the line of cut is par-
allel to the back of the notch. With a short bar, procedures shown in Chap. 21 are used to obtain
the same effect.
The cut is theoretically finished when the strip of uncut wood (the hingewood) has been
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reduced to ⁄ 10 to ⁄ 20 of trunk diameter. The tree should now fall toward the notched side in a direc-
tion at right angles to the length of the hingewood, if its balance has been judged directly. If the
hingewood tapers, direction will tend to shift toward the thicker side.
The hinge may be crushed as the tree starts to lean, and may narrow the edge of the cut, bind-
ing or even crushing the saw. It is necessary to be alert to pull the bar out quickly. It can be put
back in if the fall does not occur.
Direction of Fall. Natural direction of fall of a tree is influenced by a number of factors.
Location of its center of gravity, as affected by lean, twist, and limb location, is primary. Direction
and velocity of wind may be important.

FIGURE 1.6 Felling a tree. (Courtesy of Homelite.)