The Bottom or Undercut » The Open-faced Bottom or Undercut
The undercut is the second of two cuts that result in an open faced notch. The notch is made on the side of the tree facing the direction that you want it to fall.
The Correct Cut
1. Starting Point
Very Important -- begin at the level that will create at least a 70 degree notch opening.
2. Angle of Attack
Important -- cut upward at a 20 degree angle
3. Ending Point
Very important -- stop when the cut reaches the end point of the face cut. Ideally, you have created a 90 degree notch opening.
Common Incorrect Cuts
Here the ending point of the under cut doesn't meet the endpoint of the first cut . . .
. . . resulting in a Dutchman Notch.