DIY Basics: Essential guide to chainsaws
A chainsaw is potentially one of the most dangerous power tools.
Before using one to remove dead or diseased trees, or to cut up ﬁrewood, take adequate precautions, wear correct safety gear and concentrate on the task.
SIZE isn’t everything, as for most DIYers a 400mm bar is plenty. Longer bars can get in the way with dangerous kickback possible. Check the maximum cut diameter for a good indication of what the saw can handle.
COST tends to indicate quality. More expensive saws generally have better components and will last longer.
SAFETY GEAR is a must. You need a helmet with face shield, hearing protection, leather gloves and special chainsaw chaps to shield your legs.
Trees are taller than they seem and reach farther on the ground than you’d expect, but you can use an axe to estimate how far the tree will fall.
Hold the axe upside down at arm’s length, with the head about shoulder height.
Walk towards or away from the tree until you can sight the treetop just over the handle end, and the base under the blade.
The treetop will land roughly where your feet are.
This is just an estimate, so allow extra room if there’s something it might fall on.
Before cutting, check the crown of the tree for any dead branches that are partly broken but still attached, or broken off and tangled into other branches that support them.
If there are any such branches or other debris high up, don’t cut down the tree yourself as these can become dislodged and fall on you.
Check how the tree leans, if at all, and whether it has many more branches on one side, since this is the direction it will fall.
If there are any buildings, fences, powerlines or other obstructions in the felling zone, avoid felling DIY and call a professional instead.
Even when you’re sure which way the tree is going to fall, you’re still not ready to fell it.
Cut away any brush around the trunk and clear two escape routes on the opposite side of the tree to its direction of fall.
They should be about 45º away from each other in opposite directions.
The last thing you want is to trip while walking away from a falling tree.
The rule of thumb is to make the depth of the notch about one-third of the tree trunk’s diameter.
Try to cut the notch with a 60º angle on the upper face and 30º below.
The felling cut should be just above the apex of the notch and finish short of the notch, leaving an even uncut hinge to guide the rate and direction of fall of the tree.
To mark the notch before cutting it, first sight along the handle of the chainsaw until it is pointing in the direction you want the tree to fall.
Keeping the saw in the same orientation, bring the bar up to the trunk. Where it touches the bark will be the centre of the notch.
Mark the notch at a comfortable working height using chalk or by scoring the bark with the chainsaw.
TIP: You can shorten the stump after the tree has been felled.
Make the upper cut ﬁrst, aiming for an angle of about 60º from level, followed by the lower one, which should be angled about 30º down.
When making the lower cut, turn your hand to keep a firm hold on the rear handle, controlling the throttle with your thumb.
If the second cut meets the first perfectly, the wedge will drop out.
If it does not, extend the upper cut and then the lower cut gradually until the wedge falls out.
The felling cut should be straight and at least 25mm higher than the notch apex, finishing just short of the notch and leaving a hinge of uncut wood to guide the fall direction.
Tap wedges into the back cut until the tree begins to lean.
Pull the saw free and walk away along one of the escape routes, keeping an eye on the tree so you can react if it deviates from the planned direction of fall.
Once the tree is down, it needs to be cut it into manageable pieces.
Start by removing branches near the base of the trunk and work your way up.
Stand on the uphill side of the trunk in case it starts to roll and rest the saw against the trunk to pivot the bar through the branch.
Remove the branches as soon as they’re cut so you won’t trip on them.
To cut off parts that are pressing against the ground, start by cutting downward through one-third of the branch.
Saw upward from below to meet the first cut. Be prepared for the trunk to roll or drop, even before you’ve cut all the way through.
A chainsaw can become pinched if you cut too far through a branch that is supporting the trunk.
The cut will close, tightening and clamping around the bar and chain.
If this happens, stop the engine immediately and use a stout branch or fencing bar as a lever to lift the trunk and take pressure off the branch, opening up the cut to free the saw.
When cutting a log into 400mm lengths for ﬁrewood, first cut three-quarters of the way through, then if it is resting on the ground, roll it over to complete the cut from the other side.
If the log has a 70 to 150mm gap underneath, you can cut the whole way through, but keep the bar parallel to the ground.
As you near the end of the cut, ﬁnish with the base of the saw engine resting ﬂat on the ground to prevent the the chain from accidentally hitting the dirt.
There are various ways to sharpen a blade DIY.
Some devices can be attached to a drill and sharpen each tooth, using a guide to control the depth and angle of cut.
Others are bench mounted with a grinding disc to ﬁle the cutting edge of each tooth in turn as the chain is fed over a guide bar.
TIP: Chains can be sharpened professionally for about $10.
The chain on your saw has to be tensioned correctly.
If it’s too loose or too tight, it can damage the bar and present a safety hazard.
Most modern saws feature tool-free tensioning systems, but older models may need to be adjusted using a screwdriver and wrench.
On modern chainsaws, the bar can be loosened using a locking wheel on the clutch cover.
A knurled dial is then turned to adjust the chain tension.
A dull chain cuts slowly, wasting time and causing unnecessary fatigue.
What’s worse, it can damage the chain and the bar, as well as put extra strain on the saw.
It only takes a moment to dull the blade if you touch the ground with the chain, saw muddy wood or hit a nail.
If the chain is sharp, the woodchip from the saw will have a rough texture.
The teeth need sharpening when the chainsaw begins to eject fine sawdust instead of coarse chips.
ONLY use a chainsaw when you are fully alert and not distracted.
WEAR full safety gear.
FILL the chainsaw with petrol before beginning a cut to avoid running out halfway through.
ENSURE the chainsaw is always full of chain and bar oil.
ONCE you start working, don’t take a break until the tree is down.
NEVER cut on a breezy day, as the force of the wind can cause the tree to fall in an unplanned direction.
THE COLDER MONTHS are a good time to fell deciduous trees, as they are easier to cut up when they are free of leaves.
WRAP the thumb of your left hand around the front handle with your right hand firmly on the trigger handle.
STAY AWAY from hollowed-out trees, especially if they’re big. They are unpredictable and dangerous to fell.
Make sure you have a helper nearby when you are operating a chainsaw.
If there is no way to avoid working alone, make sure someone knows where you are so they can raise the alarm if something does go wrong.
Always keep a mobile phone on hand, and ideally enlist the help of a trusted assistant who can stand a few metres away and monitor the top of the tree for falling branches.
They can also alert you to vacate the area via one of the planned escape routes once the tree starts to fall.
Ensure helpers move away from the felling area once you start cutting at a distance at least twice the height of the tree.
Beware of kickback
Chainsaws can potentially cause terrible injuries.
Most of these are caused by kickback, which occurs when the upper part of the blade tip comes in contact with something it can’t immediately cut, such as metal or a rock, while the chain is moving.
This throws the blade upwards and towards you with great speed and force.
The hand guard normally has an integrated chain brake that locks on in the event of kickback.
Even if the chain stops, the bar is hurled so violently upwards if kickback occurs that it can still cause severe injury, so prevention is the only way to ensure safety.