Sharpening
and Maintenance
of Saw Chain
Description of chains
The illustration on the right shows the component parts of
a
STIHL
saw
chain. Every chain manufactured by STIHL
features the Oilomatic system. Apart from the three basic
types (Rapid, Topic and Picco), there are three different
versions whose names denote the cutter shape, i.e.
chip-
per
tooth = Standard,
semi-chisel = Micro and full chisel =
Super.
The
main size
measurement on a saw
chain is the pitch.
It
is
determined by measuring the distance between
one
ri-
vet and the next but one and dividing the
measurement by
two. The result is the pitch which is generally specified in
inch (3/8"
=
9.32 mm).
Like any other cutting tool, the saw chain is subject to nor-
mal wear and tear. A properly sharpened chain slices
through wood and requires
very
little infeed effort. For this
reason alone you should never attempt to cut with a dull or
damaged chain. There are a few crucial
angles
which
must
be
observed in order to obtain good results when sharpe-
ning a chain. They are explained below.
Filing angle
The filing angle for Rapid-Standard, Rapid-Micro and To-
pic-Micro chains is 35'; these chains are sharpened
to
this
angle before leaving the factory. However, if you want to
use the chain primarily for cutting hardwood or frozen tim-
ber, it is best to sharpen
it
to an angle of 300.
Rapid-Super
and Topic-Super chains
are
always
sharpened
to
30°.
It
is essential to ensure that the filing angle is kept exactly
the same on all
cutters. Irregular angles will cause the
chain
to run
roughly and unevenly
as
well
as
accelerate
the rate of
wear
and increase the risk of breakage.
Top:
Component parts
of
an
Oilomatic chain
Bottom: Measuring
chain pitch "t"
1 =
Right hand
safety
link
2 =
Right hand cutter
3 =
Preset tie strap
(with rivets)
4
=
Rivet
5 =
Drive link
6 =
Left
hand
cutter
7
=Tie
strap
8 =
Left hand
safety
link
49
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