Maintaining Your Chainsaws
We all know how our chainsaws cut when they were new
or had a new chain. That is the way we want them to cut every time we use them. If it doesn’t cut like new,
it is basically wasting time, causing damage, risking your safety. Chainsaw cutting chains are designed to be
maintained easily. At the same time, to complete the task correctly, you have to be familiar with the basics.
How Chainsaws Work
The five basic parts of a chainsaw:
Cutters are responsible for slicing and removing wood
fibers, and have two features; a depth gauge also called a raker in the front and in the back, a cutting
element similar to a gouge. There is a gulf between them called a gullet.
The cutting element’s shape resembles a “7”. It has
two surfaces (a top and side plate) that have three angles each. The easiest to distinguish is the top plate,
the 30-35 degree rake that you’ll notice when looking down at the cutter. Its best setting is at 60 degrees.
The most difficult angle to see is the side plate angle, the arc created in the side plate. Usually the angle
will be 85 degrees or less.
The top-plate and side-plate angles meet forming a
sharp corner; this cuts across the wood’s grain. The left and right-hand cutters alternate on each side.
Chips are scooped out by the angle under the top-plate. At nearly 60 MPH, the cutters take turns going
through the cut.
The depth of the ‘bites” are controlled by the depth
gauge. They are usually 0.025-0.035 inches lower than the corner, enabling it to cut.
When to Sharpen Your Chainsaw
Cutters have a thin coating of tough industrial
chrome. If only used on clean wood, they retain sharpness indefinitely. Of course that is difficult to do in
real life as wood is frequently dirty. Cautious operators wash, brush, or chop dirty areas prior to cutting.
It will save you quite a bit of time in the end.
How You’ll Know It’s Time to Sharpen:
- The chain will not self-feed; this will be quite
an obvious sign. If you have to push down on the saw in order to cut or you have to use the bucking
spikes to get more leverage, you need to sharpen the chain.
- Dusty discharge. You should sharpen if the saw is
making wood dust as opposed to wood chips
- The chain appears shiny. Inspect the top and
side-plate. The steel will be exposed when the chrome plating has been worn. You will also notice a shiny
cutting edge. In order to restore it, you have to file the steel away until the chrome comes bask.
As soon as you notice that your chain is dull, stop
cutting. If you force a dull chain, unnecessary wear is put on the guide bar, chain ect. It has been shown
that dull or poorly maintained chains are the cause of most failures that are bar related. Dull chains are
also responsible for operators becoming fatigued and frustrated. It also results in impaired judgment which
If at all possible, sharpen the saw on a workbench. It
is harder and takes more time to do it in the field. Many professional operators take many chains into the
field so if one dulls it can be replaced with a sharp one. This can be done more quickly than sharpening in
Prior to starting, confirm that the saw is steady and
that your work area has adequate lighting. Put a wood block under the bar if it moves up and down. Make sure
your chain has the right amount of tension. You can refer to your owner’s manual for the procedure. The chain
should fit snugly against your bar while being pulled easily by your hand. If the chain is loose, it will
wobble while you’re filing it. This can also cause damage to the chain, bar, and sprocket during use. Be sure
to wear leather gloves when filing because of the razor sharp edges.
A round file of the correct diameter will restore all
three angles of the chain cutter at the same time if you hold it correctly. Different chain sizes and cutter
styles require different file diameters. It is essential to use the correct size. Refer to your manual or
instruction sheet to find the right file diameter. If you still are not sure, your dealer can help you with
It is important to make sure that damage to the side
and top-plate is removed, and that the top corner is extremely sharp. If you use a file guide it will ensure
that you hold the file at the right height and orientation.
You want the simplest file guard you can find. The
best ones are plates that fall over your chain; they enable you to see what you are doing. Be absolutely
certain that you purchase the correct model for the chain.
Your Sharpening Technique
Put the file guide over the cutter, place the file on
the guide, and line it up with the witness marks on the guide. When using a clamp-on-the-file guide, place
the guide plate on the cutter and align the witness marks with your guide-bar plane.
To sharpen the chain, use both hands to hold the file.
Now you are ready to actually sharpen the chain. Hold the file with both hands. Work using broad strokes from
the inside to the outside of the cutter. Do not use much pressure and ease up on your return stroke. The
guide is performing correctly if around 20% of the file diameter is over the top plate. Do all the cutters on
one side before going to the other.
A file that is too high or too large will make a back
slope on your cutter, and it will not feed right or you will end up having to force the chain to cut. Files
that are not big enough or have been held too low result in a “hook”. Cutters that are hooked are recklessly
aggressive to begin with but then dull rapidly. By using the right size file and guide, these errors can be
File every cutter until all traces of damage are
removed. Do not forget that the top corner has to be very sharp and is defined by its chrome edge. Confirm
that both cutters have been equally sharpened, and the top plates are alike in length and angle. If it isn’t,
your chain may pull to one side when you’re cutting.
Remember the Depth Gauges
When looking at the top plate of the cutter, pay
attention to the way it slopes down to the back. That slope ensures that the corner stays at the highest
point. The corner gets lower as the cutter is being filed back. The depth gauge has to be filed occasionally
to offset the decrease in the height of the cutter. If not, the space between the cutter and depth gauge will
become too little causing your chain not to bite. This also causes the chain to stop self-feeding. The depth
gauge setting should be checked after numerous sharpenings. You can find depth gauge jointing tools to do
this. Some file guides also act as a depth gauge tool and have been pre-set to the chain’s depth gauge
When using a standard depth gauge tool, it is
important to know the recommended depth gauge clearance for your chain. If it is 0.025in find the slot that
corresponds on your tool. Put the tool over the chain and be sure the top surface sits square on the top
plates. Push it so that the gauge is in the space labeled .025.
The depth gauge is too high if it goes over the slot.
It can be lowered with a 6in flat file, stroking from the inside to the outside of the cutter. File until the
gauge and the top of the slot are flush. Do this until every gauge is the proper height. Take the tool out
and finish by rounding the edge of the rakers.
Avoid filing the gauges too low. The chain will become
too aggressive and rough, making slipping of the clutch more likely. The risk of kickback and wear on the
chain, sprocket, and bar will be elevated.
Following the manufacturer’s recommendations will give
you the best results. By properly maintaining it, you will have one of the most productive efficient machines
you have ever worked with.