Hu's and Stuarts comments on the recent chainsaw thread: http://familywoodworking.org/forums/...read.php?30874 got me thinking about chainsaw safety and what might not be common knowledge. Please feel free to add your own tips/comments.
Here are a few of the things I was taught that seemed worth calling out as they are perhaps less obvious than some of the common knowledge. I'm mostly leaving out the obvious bits about protective clothing and how to properly start/carry the saw, etc.. because that seems to be more widely known.
The worst case for a chainsaw is kickback. The main reason for kickback is if the upper tip of the saw contacts the work it will grab the bar and throw it back at you. This rough diagram shows roughly the danger spots.
The red part contacting the wood is where you can get a bad kickback. The orange on the bottom is close to the red zone so it potentially puts you at risk although a lot of pros use that area extensively. The orange section on the top is somewhat dangerous because the chain wants to push the bar so the red ends up in contact.
There are a number of cuts when you do need to use the top of the bar (especially when bucking up felled logs to do an underside relief cut and less so but some felling cuts) but its best to do it as far back on the bar as possible. Non through cuts are also problematic because you can contact the danger zone when retracting the bar; you should always at least engage the chain brake when removing the bar from the cut and possibly turn the saw off.
The kickback guard on the saw requires your hand/arm to contact it to work so your forward arm should always be mostly extended/rigid when cutting (this doesn't mean straight armed though). This is also why overhead cutting is extra dangerous because you are usually in a position where that won't happen reliably.
If you have a tip guard it does dramatically help reduce the probability of kickback (kind of like a riving knife for chainsaws) but isn't a panacea of course. Use it when you can.
The danger of kickback is also why I don't like too short of a bar because it makes it more likely to have the danger zone contact the wood (because inevitably you try to cut something larger than your saw.. do that as infrequently as you can). Of course to long of a bar also is more likely to get caught up in brush or other stuff and cause a problem so somewhere in there is a nice balance depending on what you cut.
Always at least engage the chain brake when moving with the saw on. I admit to not turning it off every time I should, but at least religiously engage the chain brake. Also test the brake periodically - your manual should have instructions for doing so.
Check the chain tension periodically, especially with a new chain. A loose chain coming off is a bad day, and overly tight chain breaking is also a bad time.
Clear shrubs and brush away from the work area. They can catch in the chain and best case whip the heck out of you and worse case grab the bar and make it go someplace you don't want (this is another common place where kickback happens when the bar grabs a twig and gets pulled into a branch/brush and then bam!). I actually use an axe a lot for limbing and cleanup because I'm more comfortable with it but it has its own dangers. This is another place where a more aggressive chain can be a problem. Basically the larger teeth are more likely to grab small pieces and not cut them but instead pull the saw or piece of wood around.
You can also often adjust your stanse so that if it does kickback its less likely to hit you in the face. Its worth spending some time prepping the cutting area so you have a nice stable place to stand with proper posture.
Also .. learn to properly sharpen your saw. Use a filing guide to adjust the rakers every 2-4 sharpenings, if you over file them you make the chain much more grabby which can be a problem as it can pull the saw in further than you wanted; especially dangerous when limbing. If you don't file them eventually the chain won't cut. An overly aggressive filing can also have similar grabby problems.