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But when does the chain need
sharpening?
The determining factor is the feed
effort.
A properly sharpened chain pulls
itself into the cut when only slight
pressure is applied. But if the chain
has to be forced into the cut by
applying excessive pressure, the
cutters are dull or have been
damaged by foreign matter.
Another clear indication of a dull
chain is fine sawdust being pulled
from the cut instead of coarse, thick
chips. It is essential to sharpen the
chain at this stage.
Working with a dull or damaged
chain requires more physical effort,
exposes the user to higher vibration
levels, produces unsatisfactory
cutting results and increases wear.
Furthermore, it results in a high fuel
consumption and a higher rate of
wear on the guide bar, chain, chain
sprocket and engine.
A saw chain can be resharpened in
several ways, i.e. with a file and file
holder, a filing tool or an electric
sharpener.
Depending on the method used, the
chain is either left on the bar or
removed from the bar.
The sharpening procedure is the
same for all chains but different
filing angles and settings are
necessary for each type of chain.
Chain and Bar Manual
3.18.1 Preparing the Saw Chain
Thoroughly clean the chain, e.g.
with STIHL resin solvent. This
ensures an optimum material
removal rate of the sharpening tool
used and avoids grinding dust
sticking to the chain. Examine the
chain for cracks and damaged
rivets. Replace any damaged or
worn parts and file the new parts
back to match the shape and wear
of the other parts.
Determine the master cutter – use a
slide caliper to find the cutter with
the shortest top plate and mark it
with chalk.
Use it as the master for sharpening
all other cutters.
All cutters must be the same length
after sharpening. Owing to the
rearward slope of the top plate the
cutter heights will be uneven if the
cutter lengths are different. If the
cutters are not the same height the
chain will run roughly and eventually
break.
When sharpening is completed the
saw chain should again be cleaned
thoroughly. Remove filings or
grinding dust and then lubricate the
chain thoroughly. Clean and
lubricate the chain before prolonged
out-of-service periods.
If the chain is resharpened at the
cutting site with a file, run the engine
briefly off load at full throttle so that
the filings are thrown off the cutting
attachment along with the chain oil.
Chain lubrication can be checked at
the same time.
3.18.2 File and File Holder
Different chain pitches necessitate
different file diameters.
Sharpening with a file is performed
in such a way that the file is set with
1/10 of its diameter protruding
above the top plate.
The use of a file holder ensures that
the file is kept at the correct height
relative to the tooth. There are
different file holders for the various
chain pitches.
The correct choice of file holder and
file diameter therefore guarantees
that the file projects 1/10 of its
diameter above the top plate.
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