Why does your chainsaw cut crooked? You are most likely to notice this when sawing larger pieces of wood, and the causes can be varied. Let's start with technique: you should start and finish the cut in a straight line, without pushing the chainsaw sideways. That way, you avoid prematurely wearing the guide bar rails, which the chain runs between, or warping the guide bar itself. Also to prevent the bar from warping, don’t use it as a lever while sawing, or force it free if it gets stuck in the wood.
The main causes of crooked chainsaw cutting are the chain and guide bar, for example if:
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The length, i.e. wear of the left and right chain teeth is uneven: this can happen when one of the sides hits a stone or piece of metal.
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The teeth aren’t sharpened correctly along one side, perhaps because they were improperly filed, without maintaining the same sharpening angle.
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The guide bar rails are unevenly worn and therefore asymmetrical, insofar as one is lower or thinner than the other.
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The guide bar track is too wide for the chain, either due to wear or because the bar is paired with the wrong chain.
It is completely normal for the guide bar rails on a chainsaw to wear out due to the constant rotation of the chain. However, if the chainsaw cuts to one side, then as we said, the problem is uneven wear. It may be due to the fact that the chain cuts at an angle, is badly sharpened, incorrectly tensioned, or not sufficiently lubricated. Uneven wear of the guide bar in turn causes the chain to rotate at an angle rather than aligned with the bar, creating a vicious circle of wear.
Your chainsaw might also cut crooked because the guide bar is incorrectly mounted or the sprocket is worn out. The sprocket/guide bar/chain system must work in a balanced way, so try to take this synergy into account when replacing the components.
In addition to correct cutting technique, the secret to making sure your chainsaw cuts straight is good maintenance:
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Carry out routine sharpening of the chain using a round file, for example: all the teeth should be sharpened and in the right way (with the same length and sharpening angle). You can find out more in our article on how and when to sharpen your chainsaw’s chain.
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Pay special attention to sharpening if you need to fix a specific problem, such as asymmetrical sharpening.
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Check and adjust the chain tension.
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Keep the guide bar and chain lubricated: here you can learn more about how the oil pump works and how to maintain it.
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Flip over the guide bar periodically, so as to even out the wear as much as possible.
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Grind the guide bar rails with a flat file or, if you prefer, take your chainsaw to the technicians at your nearest Oleo-Mac service centre.
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If necessary, change the chain, guide bar and sprocket: we recommend changing the sprocket with every second chain replacement and the guide bar with every fourth chain replacement.
Maintenance is not solely about the guide bar and chain: here are all the chainsaw maintenance jobs you need in order to avoid unpleasant situations, such as a chainsaw that stops suddenly after starting (possibility due to the carburettor flooding with fuel; by the way, here's how to prepare fuel mixture).
On the other hand, maintenance is important to ensure not just efficiency, but also safety: here you will find some rules for using a chainsaw safely.
