A while back I did a post on "The Importance of a Sharp Axe" when it comes to chopping. There I went over the basics, specifically, the need to create a wide V shaped notch in the tree so that the wood chips in between the cuts can fly off efficiently.
There is a problem however. If your axe is too small for the tree, or you simply have a very large tree, the V shaped notch you will have to make in order to get all the way through the tree will be so large that the wood chips in between the two cuts forming the V shaped notch, will not fly off. A larger axe will solve that problem to a degree, but at some point the tree will be too big for any axe to do that.
In such situations there are two methods that I use, which will help.
For the first method, start by making a small V shaped notch in the tree.
Then, start enlarging that notch by removing more wood from each side (or only one side) as you go down into the wood. This way the wood chips will come off easily, and eventually your notch will be the desired size.
For the second method, start by imagining the completed V shaped notch in the tree. Determine how large you need the top section of the V to be. Then score that section of the wood by making close unidirectional cuts.
Then, reverse the direction of the cuts and repeat the process along the same section of wood. This will result in a layer of wood being removed. You are in effect making a series of small V shaped notches next to each other.
Then repeat the same process, going further down into the wood, gradually shrinking the portion of the wood over which you make the cuts, until eventually you get the desired V shaped notch.
You can of course use a combination of the two techniques. It is the right way, if it gets the job done.