This Old House's Norm Abram says before using a chain saw, he checks the chain tension.
If it's too tight, it could wear out the bar and sprocket and can even snap. If it's too lose, it can jump off the guide bar. The chain should lift about 1/8 inch. The drive links under the chain's teeth should remain in the bar's groove.
To adjust tension, loosen the mounting nuts at the base of the bar, move the bar slightly, then retighten the nuts.
Avoid starting the saw while holding it in one hand. It should be on the ground. Make sure there is nothing touching the bar. Then:
* Engage the chain brake. If the engine is cold, pull out the choke completely.
* Put your right foot part way through the rear handle and hold the front handle firmly with your left hand.
* Pull the starter-cord handle with your right hand until the engine starts.
* Push the choke in and hit the throttle once so the engine speed drops to idle. Disengage the chain brake only when you're ready to begin sawing.
Abram leaves the big trees up to the pros, but with his 12-inch bar, he cuts smaller logs for the fireplace. It's called "bucking."
Start at the thin end of the log. It's easier to get it off the ground and on top of another log. Then you can make a single cut through the raised end without worrying about hitting the dirt.
Caution: Be sure to step back at the end of every cut so the log doesn't land on your foot.
