So let’s describe the different types of notches, and the advantages and disadvantages of each. There are three types of notches commonly used in the logging industry by chainsaw operators in tree felling:
1. Conventional notch (35 degrees plus or minus open )
Advantages:
* Most commonly used and recognized
* Almost everyone has seen it and knows how to cut it.
Disadvantages:
* Easy to bypass the cuts
* Opening is not wide enough – allowing the two face cuts to contact one another prior to the tree hitting the ground, allowing stump pull, side scarring, or worst case scenario – barber chairing.
* Much easier to cut the hinge off, since the back cut must be made above the notch cut, making judgement of the thickness of the hinge difficult.
2. Humbolt Notch (45 degree open)
Advantage(s)
* Allows the butt log to be cut without the notch cut being taken out of the log, allowing the butt log to be cut evenly and maintaining the full circumference of the log
Disadvantage(s)
* Infrequently used, especially in the Midwest, so it is not easily recognized.
* Difficult to match the two notch cuts because of the method required to cut it.
* Cannot cut the stumps as low as the other techniques because the angled cut needs to be taken out of the stump.
* The opening is not wide enough, allowing the two face cuts to contact one another prior to the tree hitting the ground, allowing stump pull, side scarring, or worst case scenario – barber chairing.
3. Open Face Notch (70 degrees or more)
Advantages:
* Much easier to match the two notch cuts, allowing the notch to work during the entire travel of the tree to the ground
* Allows the tree to fall almost completely to the ground before the two notch cuts make contact, reducing the possibility of stump pull, side scarring, or barber chairing.
* Because the bore cut is recommended in combination with the open face notch, setting the hinge width and thickness is made much easier, allowing for directional felling, and allowing the tree and stump to hold together longer, giving the feller more time to retreat into his/her escape route before the tree releases.
Disadvantages:
* Relatively new process, so not fully understood or recognized as effective.
When cutting notches, regardless of the type used, the following are some requirements in order for them to work properly.
If using the conventional or Humboldt notches, the opening must be a minimum of 45 degrees. The depth of the notch cut should be approximately 1/3rd the diameter of the tree’s DBH (diameter – breast height) The minimum width of the notch should be a minimum of 80% of the trees’ DBH. The two notch cuts MUST match at the back of the notch –bypassing one cut with the other allows the bypass to create a fulcrum which can cause stump pull, side scarring, or barber chairing.
If using the open face notch, the opening must be a minimum of 70 degrees – and 90 degrees is optimum. The depth of the notch is achieved when the width of the notch cut reaches 80 % of the diameter of the trees’ DBH. If the tree has side lean that must be controlled, a deeper notch to achieve a longer hinge is recommended. Again, the two notch cuts must match in order for the notch to work properly.
All of the notches above are acceptable and will work if cut properly. No matter which notch you choose, if it isn’t cut right, will not work right. And the other element that makes them work properly is the type of back cut used with each one. It is essential that hinge wood is left no matter which notch is used, . It has been our experience and it has been shown that the open face notch in combination with the boring technique will allow the sawyer to have better control of the tree, increase the value of the tree, and be safer in his everyday activities.