It is normal for a chainsaw chain to stretch and slack during operation. If this happens, you have to tension it as soon as possible to avoid accidents or reduced efficiency. You don’t want the chain dropping off in operation because you didn’t tension it right.
Different chainsaw brands run on different tension settings. Even though you can use the guide bar to estimate if your chain is tight enough or loose, the best way to tell is by feeling or lifting the chain to feel the amount of tension. The chain on even the best budget chainsaw shouldn’t be too loose to the extent of falling off the blade.
It also shouldn’t be too tight such that it hugs the bade snugly without flexing.
Ideally, the chain should be a bit loose on the guide bar but should be tight enough such that you cannot pull its drive links out of the bar nose. Grab the chain between your fingers and lift it a bit to see if the drive links come out.
Check this out too: How To Untangle A Chainsaw Chain
A loose chain will also disengage the drive links on the lower side of the blade making the chain look saggy and, well, loose.
A tight chain will either stall the engine in low RPMs or is hard to move with your fingers. It might also spark and smoke as it runs over the guide bar.
How to Tighten a Loose Chain
- Turn off the saw and apply the chain brake
- Let the chainsaw cool down if you have been using it. Give it a couple of minutes. The cooling will take off the expansion slack hence helping you gauge its true tightness
- Place the saw on a stable working surface and locate the chain tension adjustment screws. On most models, they are between the guide bar and the saw’s inside bucking teeth. Other saws will have it on an outboard position or between the bar nuts on the side cover. Consult your manual to locate yours
- Loosen the nuts holding the bar just enough to slide the bar up or down by grabbing on its nose. Don’t try adjusting with the bar tightened as this could damage the tension pin
- De-active the chain break
- Ensure that you hold the guide bar up by its nose at all times. This will simulate the upward movement the bar will naturally take when you are cutting wood. By keep the nose up, you will get a constant tension that will hold at all times
- Use the screwdriver to adjust the tension screw to either increase or decrease tension. Turning the screw clockwise increases tension while counter-clockwise turns to reduce tension
Here is a video from Husqvarna explaining how you should check for chain tension. The video will also teach you how to tighten the chain properly on this popular chainsaw brand.