Detail of a chain saw right hand tooth.
MOTHER EARTH NEWS STAFF
The introduction to the chapter on how to sharpen chain
saws in Barnacle Parp's Chain Saw Guide includes an anecdote about the author's buddy—a
character called Three-Legged Muskrat—who insists on
filing his saw chains by hand. Parp concludes: "Muskrat is
a real old-fashioned expert who has worked with sharp steel
all his life. When he is finished sharpening a chain by
hand, it's almost as perfect as a chain that was machine
Now if you've ever tried to lay a file to a dull chain with
nothing more than your eyesight and fingertips to guide
you, you know Muskrat must have been a near magician
with a file. And you're also well aware—if you've
ever tried hand-sharpening and failed—just how miserable
working with an improperly sharpened chain saw can be. There's no substitute for a chain that's
honed to the correct angle with its cutters
properly profiled and trimmed to equal length.
Unfortunately, most amateur lumberjacks don't know how to correctly sharpen a chain without visiting a local saw shop (at $2.50 to
$4.00 apiece) to have the job done.
We began gathering a representative sample of do-it-yourself chain saw sharpeners several months ago in an effort to remedy that situation. Through the past summer and into the fall, we put the dozen
or so contraptions to work keeping the saws used at the
Eco-Village and by MOTHER EARTH NEWS' staff members in tiptop shape.
During that time we dulled a passel of chains (they were
subjected to about every job short of ditch digging or wire
cutting), and we've come to some definite conclusions about
what does, and doesn't, make an effective chain saw
Rub Your Belly and Pat Your Forehead at the Same Time
The complexity of the task that a chain sharpening device
must accomplish is formidable, and the job is made even
more difficult by the fact that the device has to be able
to perform many of the different functions at the same
time. First, and most obvious, the tool must precisely
establish the proper angle for the cutters in relation to
the direction of chain travel. Most saw chain (known as
chipper-type) is sharpened to a 35° angle, but some
chisel types are designed to use a 30° cut. However,
many experienced saw owners prefer to use a chain trimmed
to less than the recommended angle, in order to reduce the
strain on the operator during extended periods of sawing ... or to perform special tasks, such as ripping.
Whatever the means used to control the angle of the teeth,
a good chain sharpener also needs some mechanism to prevent
the file, stone, or bur from digging too deeply into the
cutter's gullet or (worse yet) into the tie strap. This
happens all too often to chains that are hand sharpened by
amateurs. The telltale sign is teeth that are formed like
breaking waves at the beach. A chain that has been "hooked"
in this fashion not only is structurally weakened, but also
will dull quickly and pull and jerk when being used.
Furthermore, there's another angle that must be taken into
account when sharpening a saw. Some types of chain have
their cutters ground at other than horizontal. For such
chains the filing device will typically be set to point
uphill at a 5 or 10° angle.
In addition, after months of evaluation, we're convinced
that an effective chain sharpener must include a provision
for controlling the amount by which the cutters are
shortened (unequal teeth are a major cause of curved
sawing), a mechanism to grip the chain during
sharpening to prevent it from deflecting, and the
ability to deburr and smoothly finish the edge. And with
all that testing under our belts, we've come to prefer two
sharpeners to all the others evaluated, simply because they
both come closest to meeting the criteria listed above.
However, depending on the type(s) of saw(s) that you own,
one of them may to be the better choice for you.
The Gamn' sharpener is a newcomer to the market, and works
quite differently from conventional file-type sharpeners.
It hones with a carbide bur that the operator turns with a
crank (instead of employing the reciprocating motion common
to file sharpeners). Consequently, the manner in which
the Gamn' removes metal from the chain is also different
from that of a file sharpener.
There are a couple of advantages to the Gamn' approach.
First, because the blades on the bur are moving parallel to
the direction of chain travel, any irregularities produced
in the tooth's steel surface (which might be caused by
chips of metal, for example) will be aligned with the
cutting action. Thus the gouges will be much less prone to
plugging with wood resins than would be the case with a
device that trims metal perpendicular to the direction of
chain travel. In addition, the clockwise rotation of the
carbide bit won't leave a raised burr on the finished edge
of the tooth.
Moreover, the Gamn' sharpener is solidly constructed (it's
made from aluminum), clamps rigidly to the saw's bar, is
equipped with a cinch nut to hold the chain while
sharpening, has an adjustable stop for setting the cutter
length, and holds its rotating bur accurately to 35°
(and horizontal). A newcomer to sharpening can get the hang
of using it quickly, and a practiced operator should be
able to sharpen a chain faster with the Gamn' than by any
other manual method.
We have only two minor reservations about this otherwise
excellent tool. For one thing, the device is quite
uncompromising: it sharpens to only one angle (which
means some saw owners won't be able to use it), and a
different bur is required to sharpen chains of differing
pitch. (This is also the case with file sharpeners, but the
Gamn' tool's carbide bits are somewhat more expensive than
files. However, the cost may be outweighed in the long run
by the greater life expectancy of the grinder's extremely
hard burs.) Second, the Gamn' does such a fine job of
removing metal that an inexperienced or indiscriminate
user could easily whittle away a great deal of tooth in
short order. Unless the sharpener is properly adjusted (to
remove the minimum material necessary), the result could be
an oversharpened chain with a significantly shortened life
Oregon File Guide: $24.50
We tried out several different file guide chain sharpeners,
but none could approach the Oregon in either quality or
performance. It's obvious that this manufacturer of saw
chain thoroughly understood the qualities needed in the
tool before developing the specifications for the
device that bears the company's name.
The Oregon File Guide is equipped with numerous adjustments
(enough to thoroughly intimidate a newcomer at first), and
can accurately produce any conceivably useful combination
of sharpening angles. The cutter angle, measured from the
direction of chain travel, can be set anywhere between 0
and 45°, and the upward tilt is adjustable between 0
and 20° .
This Cadillac of file guides also features a pair of
screw-in clamps (for proper centering) which hold the
chain securely against the side load imposed by the file.
The length of the cutters can also be set with an
adjustable rubbing block (which prevents the file from
moving beyond a fixed amount of travel), though this
mechanism isn't as solid as is that on the Gamn'. What's
more, the Oregon has one adjustment that wasn't included on
any of the other file guides: The stop for the cutter can
be moved, which allows the operator to position the file
directly over the gullet. Thus the file will travel more
nearly parallel to the bar as it swings through its arc.
We found the Oregon tool to be significantly easier to use
than were any of the other file guides tested. Its tracking
rod fits snugly in its bushings, so the shaft doesn't
bind when a stray metal chip gets in the area. (The other
units needed frequent lubrication to prevent such an
occurrence.) A chain can be sharpened fairly quickly with
the Oregon once you learn the adjustments and
establish a rhythm. Still, the procedure was considerably
more time-consuming with the Oregon than with the Gamn'.
Though the two sharpeners that we've described here are
very different in design, both are capable of doing an
excellent job. Still, it's a good idea to take your chain
to the pros about once in every five sharpenings. Their
very precise motorized equipment will quickly rectify any
errors you might have been making with your mechanical
device. While you're there, you can
have your depth gauges adjusted as well. Furthermore, on
about every third visit to the saw shop (or
approximately once in 15 sharpenings), request that the
proprietor inspect the drive links to insure that they're
still properly profiled to fit snugly around your saw's
If you follow a maintenance schedule similar to the one
we've described, you'll find that your saw, and all of its
various subsystems (such as the bar), will last for years and that your work will go as quickly and pleasantly as
possible. Just keep reminding yourself of the
first time that you made a cut with your still
brand-new saw. There's absolutely no reason why it
shouldn't perform that well year after year!
EDITOR'S NOTE: The Oregon File Guide can be purchased
from any dealers who carry Oregon Products (they're
numerous). The Gamn' Sharpener con be ordered directly (be
sure to specify the bur size you need) from the
manufacturer, Gamn' Enterprises, Inc.
You might also find Barnacle Parp's Chain Saw
Guide by Walter Hall to be helpful. Just about every
subject having to do with the use and care of chain sows is
covered in its 257 pages.