So you want to buy a chainsaw.
Or perhaps you just need a new chainsaw bar.
Either way, you may need to consider what kind of chainsaw bar you will need. Especially what length.
Chainsaw Bar Length
Resist the temptation to slap on the biggest chainsaw bar you can find and pretend to be Conan the Barbarian. Shorter is more powerful.
A shorter bar gives a better power-to-weight ratio. The longer the bar, the more chain the motor needs to pull around, so the more the motor has to work to pull the chain around, especially when the whole length of it is buried in a tree.
A shorter bar means the same power pulling on less weight and drag, so more speed on your chain.
Chainsaw Bar Weight
You will also have to consider that you have to carry that extra weight, especially if you decide on a bigger motor to get that extra power. If you intend to cut for any length of time, that extra length and weight is going to get very heavy half-way through the day.
Another reason for a shorter bar is that Australia has some of the hardest woods in the world, and you will need that extra power to take on an Ironwood.
What size chainsaw bar can I put on my chainsaw?
Shorter might be more powerful, but you still need a chainsaw bar long enough to perform the job. The rule of thumb is that you will need a bar two inches longer than the width of the average tree that you intend to cut through.
That is the AVERAGE tree. You don’t need to be able to cut cleanly through the largest tree in the bush with one pass. When you encounter a tree with a diameter larger than your bar is long, you can cut from both sides to complete the fell.
Another factor is experience. Are you experienced? No? Then do not go above 18 inches or you will not be able to handle it safely.
Also, do not overpower your chainsaw by putting a tiny bar on a big engine – we’ll go through safety shortly.
In general, 16-18 inches is a good length of chainsaw bar for felling trees or sawing logs, but do match power to length. Here is a general chart to give you an idea of what size bar to use on your chainsaw:
- 40cc: 14-16 inch chainsaw bar
- 50cc: 16-20 inch chainsaw bar
- 60cc: 20-22 inch chainsaw bar
- 70cc: 24-28 inch chainsaw bar
- 80cc: 28-30 inch chainsaw bar
Problems of mismatching length
You could put any length of chainsaw bar on any motor, but:
If the bar is too long for the power of the motor, it might not have the power you need. It may get stuck more often, and beginners will find that more than 18 inches is hard to control.
If the bar is too short for the motor, you will get more power, but there are concerns.
If you go below the manufacturer’s recommended shortest bar length, you’ll be running those revs higher than the motor can handle, possibly damaging the motor.
Also, the extra speed and reduced inertia from the lower tip weight could have the saw kicking back sharply before you can react, and you could end up wearing it.
Most chainsaws now have safety brakes if they kick back, but you really don’t want to rely on it, and a weighty chainsaw to the face is still likely to ruin your afternoon.
How to measure the chainsaw bar
When asked for the chainsaw bar’s Called Length, this means the usable length of the chainsaw from the motor to the tip.
Most chainsaw bars have their length engraved into the metal near the base of the bar, usually as the first two numbers of the serial number. There is more information on the bar as to what kind of chain would fit, like Gauge, Pitch and Tooth Count, so if you aren’t sure what you are looking at, measure it yourself, like so:
Take a tape measure and measure from where the bar meets the motor casing. Measure to the tip of the bar. Chains will come in two-inch increments, so round up to the nearest two inches. That is your Called Length.