Back Cut
The back cut is the final cut in felling a tree. It is made from the side opposite the notch and stops short of it, leaving a strip of hinge wood that keeps the tree attached to the stump and helps control its fall. OSHA’s logging standard also calls it the felling cut.
Sources: 29 CFR 1910.266 - Logging operations, Occupational Safety and Health Administration (OSHA) ; Logging eTool: The Back Cut - The Conventional Back Cut, Occupational Safety and Health Administration (OSHA)
The hinge: what the back cut must leave
OSHA’s logging standard says every back cut must leave enough hinge wood to keep the tree attached to the stump through most of its fall, which lets the hinge steer the fall in the intended direction. OSHA’s logging eTool tells the sawyer to stop the cut where the remaining hinge will be one-tenth of the tree’s diameter wide.
Cutting too deep defeats the purpose: the eTool warns that the hinge then breaks almost immediately, the fall becomes inaccurate, and the bar or saw may be damaged.
Sources: 29 CFR 1910.266 - Logging operations ; Logging eTool: The Back Cut - The Open-faced Back Cut ; Logging eTool: The Back Cut - Incorrect Backcutting
Where the back cut goes
The back cut is level, and its height depends on the notch. OSHA’s logging eTool places it at the same height as the notch corner for an open-face notch, an inch or more higher than the bottom cut of a conventional notch, and an inch or more higher than the top cut of a Humboldt notch.
The logging standard requires the back cut to sit above a horizontal face cut, which leaves a step that helps keep the butt from kicking back off the stump; the rule does not cover open-face felling, where both face cuts are angled, or tree pulling. The eTool warns that a back cut below the notch makes the tree more likely to sit back on the stump, while one too far above it makes it more likely the tree will have to be pushed or pulled over.
Sources: Logging eTool: Making the Cuts - Kinds of Notches ; 29 CFR 1910.266 - Logging operations ; Logging eTool: The Back Cut - Incorrect Backcutting
Leaning trees: bore cuts and wedges
Heavy forward lean raises the risk of a barber chair, where the pull of the lean splits the trunk instead of folding the hinge. UGA Extension recommends cutting an open-face notch and then boring through the trunk to form the hinge, which lowers the chance of being hurt by a barber chair. It warns that the other methods leave the sawyer standing at the tree and still cutting hinge wood once the tree starts to fall, which is a very dangerous spot if a barber chair happens.
Back lean brings the opposite problem, called setback: the tree settles back onto the saw while the bore cut or the back cut is being made and pinches it, and UGA adds that in the worst cases the tree can topple back onto the feller. UGA advises putting a wedge in every tree being felled, and OSHA’s logging eTool describes driving wedges into the back cut to fell a large tree against its lean; how much back lean can be overcome depends on the tree’s height and diameter. UGA closes by stressing a systematic approach to felling and the value of training and education, so treat this page as exam study, not felling instruction.
Sources: Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243) ; Logging eTool: Special Techniques for Felling Difficult Trees
Whose rules are these?
The OSHA requirements on this page come from 29 CFR 1910.266, OSHA’s logging standard, and from OSHA’s logging eTool. The standard was written for logging: it sets safety practices for all types of logging, whatever the end use of the wood. OSHA’s tree care industry page says tree care employers must comply with the general industry standards (29 CFR 1910) and lists ANSI Z133.1, Arboricultural Operations Safety, among the voluntary ANSI standards that may apply to tree care, adding that these are not OSHA regulations and that meeting an ANSI standard does not guarantee compliance with OSHA policy.
Sources: 29 CFR 1910.266 - Logging operations ; Tree Care Industry: Standards
How the ISA arborist exam tests it
Felling questions ask what the hinge left by the back cut does, where the back cut goes behind an open-face notch, and how a bore cut or a wedge handles heavy forward lean or slight back lean. Try 4 reviewed practice questions:
In directional felling, what is the main purpose of the hinge wood left between the notch and the back cut?
Show answer and explanation
Correct answer: A. To hold the tree to the stump and guide it in the intended direction
OSHA's logging standard requires the back cut to leave enough hinge wood that the tree stays attached to the stump through most of its fall, which lets the hinge guide the fall in the intended direction. Sawing through the hinge removes that control. Wedges keep the kerf open and can help tip the tree, but holding the tree up is not the hinge's job, and a butt sliding off the stump is a loss of control.
- B: Wedges help tip the tree or keep the back cut open; the hinge is meant to control the fall, not prevent it.
- C: Wedges, not the hinge, are used to keep the bar from being pinched.
- D: A butt leaving the stump means the hinge has failed and the tree is out of control.
Source: 29 CFR 1910.266 - Logging operations, Occupational Safety and Health Administration (OSHA)
Report a problem with this question · ID safe-025
A sawyer has cut an open-face notch, made with two angled cuts, and is ready for the back cut. According to OSHA's logging eTool, where should the back cut be placed?
Show answer and explanation
Correct answer: B. Horizontal, level with the corner where the notch cuts meet
OSHA's logging eTool compares notch types: for an open-face notch the back cut is horizontal and level with the notch's corner, whereas for a conventional notch it sits at least 1 inch higher than the bottom cut. Under the logging standard, the back cut must be above a horizontal face cut to give a platform that prevents kickback, but that requirement excludes open-face felling, where both face cuts are angled, and tree pulling operations. Placing the back cut below the corner or partway up the notch opening does not match the eTool's placement for an open-face notch.
- A: The eTool calls for a horizontal back cut at the same height as the notch corner, not an angled cut below it.
- C: The eTool places the back cut at the height of the notch corner, not partway up the notch opening.
- D: A back cut at least 1 inch higher than the bottom cut is the eTool's placement for a conventional notch; for an open-face notch the back cut is level with the corner.
Sources: Logging eTool: Making the Cuts - Kinds of Notches, Occupational Safety and Health Administration (OSHA) ; Logging eTool: Making the Cuts - Kinds of Notches, Occupational Safety and Health Administration (OSHA) ; 29 CFR 1910.266 - Logging operations, Occupational Safety and Health Administration (OSHA) ; 29 CFR 1910.266 - Logging operations, Occupational Safety and Health Administration (OSHA)
Report a problem with this question · ID safe-055
A sawyer must fell a large hardwood with a heavy forward lean. Which cutting plan best reduces the risk of a barber chair?
Show answer and explanation
Correct answer: D. An open-face notch, then a bore cut through the trunk to create the hinge
A barber chair happens when a leaning trunk's forward pull is strong enough to split it but not strong enough to fold the hinge, so the butt rises and can strike the sawyer. UGA Extension notes that heavy, front-leaning trees are a common cause and recommends cutting an open-face notch and then forming the hinge with a bore cut through the trunk, which places less force on the wood fibers. Working a standard back cut in from the rear keeps the sawyer behind the tree while the trunk is under the most tension.
- A: A back cut worked in from the rear keeps the sawyer behind the tree while the heavily loaded trunk is most likely to split.
- B: Without a notch there is no hinge to guide the fall, and the trunk is very likely to split or fall out of control.
- C: A deep notch with a fast back cut from behind still leaves the sawyer at the tree as the heavily loaded trunk starts to go, the spot UGA calls very dangerous if a barber chair happens.
Sources: Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension ; Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension ; Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension
Report a problem with this question · ID safe-027
A sawyer must fell a tree that has a slight back lean. According to UGA Extension, which step helps keep the tree from setting back onto the saw and pinching it during the back cut?
Show answer and explanation
Correct answer: A. Setting a felling wedge in the back cut, as with any tree felled
UGA Extension describes setback as a tree with back lean settling back onto the saw during the bore cut or back cut and pinching it, and in extreme cases falling back onto the feller. It recommends identifying lean before cutting, putting a wedge in any tree being felled, and using ropes as needed. The same publication warns against deep notches with angles under 45 degrees and says to run the saw at full power, and OSHA's logging eTool places the back cut level with or above the notch corner, not below it.
- B: UGA Extension warns against using a deep notch with an angle of less than 45 degrees.
- C: OSHA's logging eTool places the back cut level with the notch corner for an open-face notch and, for a conventional notch, at least 1 inch higher than the bottom cut, never below it.
- D: UGA Extension advises keeping the saw at full power while cutting, since that helps prevent pinch kickback.
Sources: Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension ; Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension ; Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension ; Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension ; Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension ; Logging eTool: Making the Cuts - Kinds of Notches, Occupational Safety and Health Administration (OSHA) ; Logging eTool: Making the Cuts - Kinds of Notches, Occupational Safety and Health Administration (OSHA)
Report a problem with this question · ID safe-054
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Common mistakes in the field
Misplaced or sloping back cuts
OSHA’s logging eTool lists the usual errors. Where the notch has a horizontal face cut, a back cut level with it greatly increases the chance that the butt kicks back off the stump. A sloping back cut makes the hinge less effective or inaccurate, and an angled back cut behind an inadequate notch makes a barber chair more likely and lets the hinge break early.
A deep, narrow notch or a high back cut
UGA Extension ties these errors to stump jump, where the hinge fails and the tree comes off the stump out of control. It advises against a deep notch narrower than 45 degrees and against placing the back cut too high, and says an open-faced notch of 70 to 90 degrees with a bore cut makes stump jump much less likely.
Staying at the stump
OSHA’s logging standard requires the feller to plan and clear a retreat path before felling starts, running diagonally away from the expected line of fall, and to move a safe distance away along it as soon as the back cut is made. UGA Extension, which puts the escape route at about 45 degrees to the direction of fall, says workers should already be moving along it, away from the falling tree, when the tree starts to move.
Sources
- 29 CFR 1910.266 - Logging operations, Occupational Safety and Health Administration (OSHA)
- Logging eTool: The Back Cut - The Conventional Back Cut, Occupational Safety and Health Administration (OSHA)
- Logging eTool: The Back Cut - The Open-faced Back Cut, Occupational Safety and Health Administration (OSHA)
- Logging eTool: The Back Cut - Incorrect Backcutting, Occupational Safety and Health Administration (OSHA)
- Logging eTool: Making the Cuts - Kinds of Notches, Occupational Safety and Health Administration (OSHA)
- Chainsaw Safety: Preventing Common Tree Felling Accidents (Circular 1243), University of Georgia Cooperative Extension
- Logging eTool: Special Techniques for Felling Difficult Trees, Occupational Safety and Health Administration (OSHA)
- Tree Care Industry: Standards, Occupational Safety and Health Administration (OSHA)
Written in our own words from the public sources above, checked October 19, 2026. Arborist Practice Test is not affiliated with ISA.