alex:
<font face="Verdana, Arial" size="2">Why is limbing harder on an axe than felling?</font>
Mainly because the wood is smaller, the larger the wood, the easier the contacts are on the blade as the pressure is reduced. Also, trees are usually limbed out after the wood has been felled some time ago (8 months or so). During this time the limbs will season and get very hard as compared to the trunk of the tree which was chopped through when it was felled.
However it gets even worse. As Greenjacket noted the mechanics are very different among the two. A bad hit when felling usually will just cause a glance and while dangerous to you, doesn't pose much of a threat to the axe. On the otherhand during heavy limbing the edge of the axe can experience very strong torques as well as lateral impacts on the primary grind above the edge.
If the above doesn't sound to bad then imagine the following :
Get a hardwood dowel about 3 feet long and 1.5" in diameter. Put the blade in a vice holding it edge up at about a 45 degree angle. Bring the dowel down as hard as you can and hit the blade where the edge intersects the primary bevel. Vary the angle and impact points a little and repeat. Then again vice the blade and this time point the edge straight up. Use a hammer to set the edge in the dowel perpendicular to the grain. Now wrench the dowel to the side as hard as you can breaking the edge out of the wood. Try this at various depths.
I don't recommend doing this as it is likely that the blade would come lose from the vice, but that is along the lines of what a blade can experience during limbing.
Now of course it is not necessary to limb in this way. You can vastly reduce the beating the edge will take by taking more cuts to go through a limb using a counterstroke on all limbs and even notching them fully if you desired. And overall progressing at a much slower and careful pace. If you only have a limited amount of work to do this is the optimal way to proceed, especially if you were in some kind of survival situation and wanted to prolong the edge of your knife. However if you are working against the clock to clean up the winters wood, you generally have to press on fairly hard.
There are lots of other techniques as well, for example on the worse types of limbs, which are dead and/or frozen, you can often beat them off with the poll of the axe or even a stout club. However this is not practical if you have to handle the wood, again for the winters burning as the limbs will not be cleanly cut and the sharp edges that are left make the wood much too difficult to handle and can easily rip through your skin.
In regards to an axe vs a chainsaw, a lot of it depends on how much you have to do. I have limbed about about 250 small sticks in the past couple of days with a couple of large knives. A chainsaw would be much more tiring to use because of the weight, even the smallest cannot be handled deftly with one hand and thus allow a quick cleanup of small wood.
For felling really large wood, then yes a chainsaw will process the tree easier than an axe, but for any kind of survival/wilderness living that is way beyond the size of a tree needed for any shelter or fuel. As well, trees that size are very difficult to handle. Any tree of decent density (spruce and above), is extremely heavy once you pass about 8" and even chopped up into lengths is not trivial to shoulder. If you have not done it before, the shear across your chest will be very painful even if you can handle the compaction on your shoulder. You would be much better off felling and cleaning up multiple smaller trees.
In regards to survival chainsaw vs axe, is also an easy choice because as Greenjacket noted the upkeep of a chainsaw. It would be like asking which is a more important skill, knowning how to navigate by the sun as Davenport illustrates on his site, or knowing how to use a GPS. If you have some kind of GPS device then you are in good shape, however depending just on it, is probably not a great idea.
-Cliff
[This message has been edited by Cliff Stamp (edited 06-14-2001).]
