Would love to talk more about the picture, but I'll behave.
OK, using wedges to fell a tree. I think it's good to look at the entire felling process, and using wedges are just an important part of that.
Felling Plan:
- Look at any hazards around the tree to be felled. Dead branches hanging above, nearby hung up trees, etc.
- Check the lean of the tree. Identify the good side and bad side if any. How is the tree's weight distributed, wind load, snow load, etc.
- Choose the path you want the tree to fall and pick a target.
- Indentify your flight path and make sure it is clear.
- Plan hinge thickness and length.
- Plan the back cut.
Action:
- Cut the proper notch keeping the target in mind. Remember, the notch is going to set the hinge length
- Plunge cut, and set the hinge thickness.
- Back cut and set wedges as soon as possible. Finish back cut leaving a small piece uncut for the trigger.
- Cut trigger and safely flee.
- If the tree doesn't start falling after the trigger is cut, then start pounding the wedge(s) further in, tree starts falling, flee...
Now, as I was taught, the direction the tree falls is controlled by the hinge. Since a proper sized hinge is really important, setting the hinge dimensions while the tree is standing is important. Once the hinge dimensions are set, and you start back cutting, wedges may be placed in the back cut as soon as there is space to do so. Leaving the trigger until last keeps the tree from sitting back on your saw, and allows you to spend less time at the base of the tree when it starts falling.
Starting a back cut from the outside of the tree, cutting towards the hinge is not as safe. In this case, the hinge dimensions are not set until you are almost done cutting, meaning you may still be cutting while the tree is falling opposed to fleeing. This is called chasing the hinge. This method may also be prone to causing a barber chair.
Back to the wedges, they're going to help convince the tree to go in the direction you want it to fall. This makes it easier as well as adding insurance. Wedges are so effective, they can actually help lift a tree and fell it against its lean if you really need to fell the tree in the opposite direction. Also, because the hinge controlls where the tree falls, the wedges may be placed anywhere there is space in the back cut (the wedge isn't controlling the direction...again the hinge is)
Ugg, I am rambling. Not enough coffee...