What Is A Felling Cut (Hinge Thickness)
A felling cut is the cut made from the back of a tree after a directional notch has been made. The uncut wood left between them is the hinge. A sound hinge helps guide the tree toward the notch, but it cannot guarantee control. About 10% of the tree’s diameter is a common starting estimate, not a universal safety rule.
A clear plan can prevent wasted effort and help you recognize when a tree is beyond your skill or equipment. Felling can also cause severe injury or property damage. Saving money on a professional is not worth the risk when a tree has a heavy lean, defects, nearby hazards, or an uncertain fall path. In my teaching, I’ve found that understanding the hinge is useful, but knowing when not to cut is just as important.
Equipment Setup and Felling-Site Safety
The hinge is the strip of holding wood between the directional notch and the back cut. Before making either cut, assess the tree, the site, and your equipment. A felling plan is specific to that tree; no single saw size or hinge measurement makes every situation safe.
Start by looking at the tree and its surroundings, not just the trunk. Check for a heavy lean, an uneven crown, dead limbs, trunk cracks or decay, wind, slope, nearby structures, people, and overhead hazards. Trees near power lines, or trees whose condition or fall path you cannot control, need a qualified professional. Do not work under a hung-up tree or try to bring it down by cutting its support.
Wear the protective equipment required for the job, including head, eye or face, hearing, leg, hand, and foot protection. Clear people and obstacles from the danger area. Plan two clear escape routes angled away from the expected fall direction, and know which route you will use. If you cannot establish a safe work area, stop.
The saw must be maintained and used according to its manufacturer’s instructions. Use an approved bar and chain combination that can reach the planned cut from a stable position. Do not stretch, reach around the trunk, or cut above shoulder height to make an unsuitable setup work.
Directional Notch, Hinge, and Field Cutting Sequence
A directional notch, also called a face notch, is the opening cut on the side toward which you intend the tree to fall. The back cut is made from the opposite side. The hinge is the wood left between those cuts. Its role is to help guide the tree as it begins to fall, not to overpower its weight or correct a poor plan.
First select the intended lay, the planned direction of fall, and a felling method suitable for the tree. Make the notch so its opening and alignment suit that plan. A common open-face notch has an opening angle of about 70 to 90 degrees, which helps keep the notch open as the tree starts moving. A conventional, narrower notch is often about one-quarter to one-third of the tree’s diameter in depth. These are common references, not rules to apply automatically.
The back cut is then made from the opposite side while leaving the planned hinge intact. With a conventional notch, it is commonly placed slightly above the notch’s horizontal cut. Open-face methods use their own geometry, so do not apply that offset without checking the chosen method. In either case, cutting through the hinge removes the wood that is meant to help guide the fall.
How thick should the hinge be?
A common starting estimate is a hinge thickness of about 10% of the tree’s diameter at the cut. For example, if the trunk is 30 cm (about 12 inches) across, that estimate is about 3 cm (about 1.2 inches). This is a field guideline, not a guaranteed safe dimension or a universal requirement in ANSI Z133 or OSHA 29 CFR 1910.266.
Species, tree size, lean, decay, and the felling method can all affect what is appropriate. A hinge that looks sound from outside may not hold well if the wood is split or rotten. Do not rely on a calculation to make a hazardous tree safe. If you cannot judge the tree’s condition or make the planned cut from a stable position, get expert help.
| Situation | What the guideline can tell you | What it cannot tell you |
|---|---|---|
| Sound tree, straightforward site | About 10% of diameter is a common starting estimate for hinge thickness. | It cannot guarantee that the tree will fall as planned. |
| Heavy lean or uneven crown | The tree’s weight and lean may dominate its movement. | A thicker hinge cannot reliably overcome severe lean. |
| Cracks, decay, or split wood | The trunk may not hold together as expected. | A measurement cannot show that hidden wood is sound. |
| Wind, slope, nearby property, or people | Site conditions can change the risk and fall path. | A standard notch and hinge cannot remove those hazards. |
A useful way to think about the hinge is as a guide, not a brake. If the tree’s weight, lean, defects, or surroundings exceed your training or control, do not proceed with routine ground-felling cuts.
Safe sequence at a glance
- Assess the tree, site, fall path, and hazards. Establish an exclusion zone and two clear escape routes.
- Inspect the saw and select a felling method suited to the tree. Make the directional notch and check that it points toward the intended lay.
- Start the back cut from a stable position and preserve the planned hinge. Keep watching the tree and do not continue if it moves unexpectedly, the cut binds, or the hinge appears compromised.
- If conditions change or the tree does not behave as expected, stop and withdraw along the planned route. Do not improvise beneath a hung-up tree.
This is an overview, not a substitute for hands-on training. Felling techniques vary, and a cut sequence should be learned from a qualified instructor using the relevant equipment and current local rules.
Chainsaw Inspection, Chain Sharpening, and Tuning
A sharp, properly adjusted chain and a working chain brake are part of a safe felling setup. Inspect the saw before cutting and follow its manual for maintenance, fuel, and chain oil. These checks do not make a risky tree safe, but they can help prevent equipment problems from adding to the danger.
Before use, check the chain brake, chain tension, sharpness, bar, controls, and fuel and oil systems. A loose, damaged, or dull chain can make cutting harder to control. Do not use a saw with a faulty brake, damaged bar, or other problem that the manufacturer says requires repair. If you are unsure how to inspect or adjust it, consult the manual or a qualified service shop.
Use the fuel and chain oil specified by the manufacturer. Do not assume that one fuel mix or oil suits every saw. If the chain needs sharpening, use the specified angle and filing method, or have it sharpened by a service professional. A saw that pulls to one side, cuts unevenly, or requires unusual force may need attention; stop and check it rather than forcing the cut.
ANSI Z133 and OSHA 29 CFR 1910.266 contain safety requirements relevant to arboricultural and logging work. Applicable rules depend on the work and location. Neither standard provides one hinge thickness that guarantees control for every tree. Follow current requirements, workplace procedures, and local rules.
Shutdown, Cleaning, and Seasonal Storage
After the tree has fallen and the area is safe, disengage or secure the saw as you have been trained, then retreat by the cleared route. Watch for falling limbs and movement from the trunk. Once the area is safe, shut down the saw and let it cool before cleaning, inspection, transport, or storage.
Do not approach a fallen tree until you have checked for unstable limbs, tensioned branches, and trunk movement. If the tree is hung up or caught in another tree, keep clear and contact a qualified professional. Do not cut its support or try to pull it down with improvised methods.
After the saw cools, clean it and inspect the chain, bar, and body for damage. Follow the manual for storage, including how to handle fuel and chain oil. Seasonal storage steps vary by model, so use the manufacturer’s instructions rather than a generic procedure.
Illustrative planning scenarios
These examples show how conditions can change a decision. They are not real incident reports or cutting instructions.
- Sound tree with a clear lay: A learner identifies the intended direction, plans escape routes, and checks the notch and hinge method against training. The conditions may be suitable for a trained operator, but the 10% estimate alone does not decide that.
- Tree leaning toward a shed: The target is close to property, and the natural lean points toward it. A routine notch and hinge may not control the result. The safer choice is to stop and seek a qualified feller.
- Tree with a crack near the base: The visible defect raises concern that the trunk could split under load. A standard hinge calculation cannot confirm sound holding wood. Do not proceed with routine ground felling.
Key takeaway: The hinge is intentional holding wood, but it is only one part of a felling plan. If the tree’s lean, condition, or surroundings are beyond your training, leave the cut to a qualified professional.
Frequently Asked Questions
What is a felling cut?
It is the cut made from the back of a tree after the directional notch is made. It leaves hinge wood between the two cuts.
What is hinge thickness?
It is the thickness of the uncut wood left between the notch and back cut. That wood helps guide the tree as it begins to fall.
How thick should a felling hinge be?
About 10% of the tree’s diameter at the cut is a common starting estimate. It is not a universal rule or a guarantee of safety.
Do you cut through the hinge?
No. Cutting through it removes the intended holding wood. Follow the felling method you have been trained to use.
How wide should a face notch be?
An open-face notch commonly has an opening angle of about 70 to 90 degrees. The suitable geometry depends on the tree and method.
How deep is a conventional notch?
A conventional notch is commonly about one-quarter to one-third of the tree’s diameter in depth. Do not apply that range to every tree or method.
Where does the back cut go?
With a conventional notch, it is commonly slightly above the notch’s horizontal cut. Other methods use different geometry, so follow the chosen method.
Can a thicker hinge control a leaning tree?
Not reliably. Heavy lean, crown weight, decay, wind, and poor site conditions can defeat a routine felling plan.
Do ANSI or OSHA rules set one hinge thickness?
No universal hinge dimension guarantees control for every tree. Follow current applicable standards, workplace procedures, and local rules.
When should I hire a professional?
Do so when a tree has severe lean or defects, is near power lines or property, has an uncertain fall path, or exceeds your training or equipment.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
