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must learn to file before the
chain gets dull.
File comfortably
Both hand and electrical chain
filing can give good results. The
electrical is faster and simpler.
For hand filing, we recommend
a double file with a built-in filing
gauge. (Pferd 4 mm, part. no.
9999-000-0400).
It is much easier to sharpen the
chain if you have a proper work
place. Fasten the guide bar in a
screw vice or a saw clamp.
Best is to build a table next to
the sawmill for filing and other
chain-saw maintenance. If you
have an electric saw, you will
need a file block (part. no. 9999-
000-0620) to hold the chain
during filing.
Avoid chain breaks
If you saw too long with a dull
chain, it can break under the
cutter where the material is
worn.
If, on the other hand, a drive link
breaks the reason can be that
the chain and the sprocket are
not matched. For best results
you should alternate five chains
on one sprocket. When the
chains are worn out, replace the
entire set, including the
sprocket. A new chain placed
on a worn down sprocket can
break during the first few minu-
tes.
It is not good to drive a normal
3/8” chain and a PMX chain with
the same sprocket.
The guide bar can pull
askew
If the chain has been damaged
on one side or filed unevenly,
the guide bar can steer askew.
The guide bar will be pressed
up or down or jumps when it
leaves the log. This way the
chain wears more on one bar
rail and if you continue to saw,
the guide bar will be worn
lopsidedly. Even if you change
the chain, a worn down guide
bar can steer wrong and the
new chain can be worn down.
A lopsided guide bar can be
fixed. File the bar rails until they
are even, using a tool like a UKF
file (part. no. 9999-000-0450).
Another, more common reason
that the guide bar pulls askew is
that it is so worn out that the
drive link bottoms in the bar
groove and the chain looses its
support from the guide bar
walls. This can be seen on the
chain in that the tip of the drive
link becomes worn.
The best chain oil
In order for the chain oil to work
well it must be viscous and
thready. When you place a drop
between the thumb and the
index finger and then open
them, long threads should form.
Edge in the chromium layer
The cutter on a chain-saw chain
is covered with a very thin
chromium layer, giving a very
sharp and durable edge.
As long as the edge is in the
chromium layer, your chain will
have perfect sharpness.
However, after between 50 and
100 cuts with the M7, the edge
in the chromium layer will be
worn down. At that point it is
time to file the chain. If you are
really sensitive, you will notice
that the chain slows up, the
guide bar heats up and the feed
pressure must be increased. If
you file as soon as you sense
that the chain is no longer
perfectly sharp, you will need
only a few, light pulls with the
file.
If you always file before the
chain becomes dull, wear on
the guide bar and chain will be
minimal.
However, if you make 5-10 cuts
after the edge has left the
chromium layer, the chain will
be so dull it will be difficult to
saw. The sawing speed will be
low and the feed pressure high.
The guide bar and chain will
easily overheat. It is still
possible to saw, but the
equipment will wear out very
quickly.
When you file a chain, there is a
real danger that you won’t reach
the chromium layer. The chain
may feel sharp, but because it
isn’t in the chromium layer, it will
become dull again very quickly.
If you don’t file in time, you will
have to remove a lot of the
cutter to get it sharp. The
working life of the chain will be
short. And if a lot of the sawing
is done with a dull chain, you will
need a high feed pressure, with
consequent rapid guide bar
wear and a high risk for chain
breaks.
In conclusion, file before the
chain is dull so that you avoid
getting into a vicious circle
where the wear on the sawing
equipment increases and the
sawing result goes down.
Regular chain sharpening
is especially important if
you are sawing wood that
is aggressive to the chain,
such as dry material, hard
wood or wood with sand or
earth in the bark.
