Assuming that you’re cutting in an area where power lines, houses, cars, etc. are not a factor, the technique for taking down a large tree is fairly straightforward: Eyeballing the beast, you judge - by its natural lean and weight distribution - which way it wants to fall.
Then you cut a wedged-shaped notch into the side of the trunk that coincides with the direction of the lean. After you remove the notch, you execute a back-cut on the opposite side of the tree.
As your back-cut approaches the notch, the tree will, theoretically, surrender to the notch, and to gravity. All that’s left to do is dance a few quick steps back from the splintering force and, shout, “TIMBERRRRRRR ….. .”
And if you misjudge a tree’s intentions …?
A couple of days ago I went to work on a 75-foot-tall ash with a 20-inch-diameter trunk. It was a little squirrelly - the bottom part of the trunk leaning one way, the top part leaning the opposite way. But I thought I had it figured out.
I cut my notch, then started the back-cut. As I closed in on the notch, the tree didn’t do what I expected it to do. Sensing trouble, I pulled my saw out just in time; the tree rocked back and closed up my cut. Then it just stood there - who-knows-how-many tons of wood held vertical by about an inch of trunk. A highly dangerous situation.
Now, there was a day, I’m sorry to admit, that I might have pressed the issue - with wedges, or another cut, or some other foolhardy scheme.
But this time, I packed up my saw and walked away, confident that the next decent wind would finish the job. Since the tree was on private property, in the dead of winter, in an area unlikely to see any human activity, I felt certain the tree wouldn’t jeopardize anybody’s safety.
I went back the next day, and the tree was down - in exactly the spot I thought it wanted to fall. No harm done.