A Field Guide to Skid Steer Buncher Safety Risks

You stand at the base of a 60-foot loblolly pine leaning toward your neighbor’s roof. The chainsaw idles in your hands while you stare at the trunk, paralyzed by a single question: which notch do I cut first? This moment—when the wrong notch choice turns a routine removal into a catastrophic barber-chair or hung tree—is exactly why every property owner and tree worker must understand felling notch design. By the end of this article, you will know the three fundamental notch types, the physics behind each, and the exact scenarios where one saves the tree and another saves your house. I’m Michael Hartman, ISA Board Certified Master Arborist, and I’ve taught these cuts to hundreds of climbers and homeowners across Texas over three decades.

The Physics Behind a Felling Notch

A felling notch is not just a starting cut—it is the mechanical hinge that controls the tree’s entire descent. The notch creates a 70-degree face opening that guides the tree’s center of gravity past its tipping point while maintaining a 1-inch thick hinge of live wood. This hinge acts like a living bearing, providing directional stability during the entire fall. Get the notch angle wrong by even 10 degrees, and the tree will either fall backward (undercut) or shear the hinge prematurely (overcut), both of which create dangerous, unpredictable movement.

The notch depth directly correlates to tree diameter: for trunks under 24 inches, cut one-third through; above 24 inches, cut only one-quarter through. This prevents the notch from weakening the hinge below 10% of trunk diameter, the minimum required to maintain directional control. Species matters too—brittle pines need shallower notches than flexible hardwoods to prevent fiber tear-out along the hinge.

Open Notch (Standard 70°): The Universal Workhorse

The open notch—45-degree top cut meeting a 70-degree bottom cut—is the first cut every arborist learns because it works on 90% of trees under normal conditions. The wide 70-degree opening gives you visual confirmation of the intended fall path and provides extra margin for error on your back cut placement. Cut the bottom face first, 1/3 through the trunk, making it perfectly level. Your top cut should meet this plane exactly; any mismatch creates a step that will roll the tree off line during fall.

The open notch excels on straight trees with minimal lean, trunks under 30 inches diameter, and when you have clear landing zones. It wastes the least wood and leaves the cleanest stump. However, it performs poorly on heavily leaning trees (greater than 5 degrees) or when the lean opposes the desired fall direction, where the hinge can close prematurely and cause the tree to sit back on the stump.

Conventional Notch (45°/45°): For Precision and Tight Spaces

The conventional notch uses identical 45-degree angles for both top and bottom cuts, creating a narrower 90-degree opening. This design provides more hinge wood and better control in confined areas, particularly useful when dropping trees between buildings or near power lines. The steeper angles reduce the chance of the tree sliding off the stump during the initial hinge bend, making it superior for trees with slight back lean.

The key difference lies in the back cut relationship: the conventional notch requires your back cut to be exactly 1 inch above the notch apex, creating the ideal 1-inch hinge thickness. Any higher and you lose directional control; any lower and you risk stump pull. This notch works best on hardwoods like oak and maple where the extra hinge strength prevents fiber tear-out during the fall.

Humboldt Notch: The Lean Fighter

The Humboldt notch inverts the conventional design—instead of upper and lower face cuts, you make a single 45-degree cut from the side opposite the lean, creating a step that prevents the tree from sliding backward during the fall. This notch is essential for trees with significant forward lean (5-15 degrees) where gravity already wants to pull the tree past the hinge.

The Humboldt shines on large-diameter softwoods and in situations where you need maximum control against the lean. The step creates a mechanical stop that prevents the tree from jumping the stump when the hinge closes. However, it wastes more wood and leaves a higher stump, making it less desirable for timber harvesting or when you need the lowest possible cut.

Critical detail: the Humboldt step must be exactly horizontal and extend exactly 1/3 through the trunk. Any angle in the step will cause the tree to roll off line. This notch requires two saw operators on larger trees—one to hold the step cut while the other completes the back cut to prevent the saw from binding.

When to Choose Each Notch Type

Tree lean is the primary decision factor. Use open notch for straight trees under 30 inches diameter with minimal lean. Switch to conventional when you need extra hinge strength for hardwoods or trees in tight quarters. Reserve Humboldt for forward-leaning trees over 5 degrees or when the lean opposes your desired fall direction.

Tree species also dictates choice: brittle conifers (pine, fir) prefer the open notch’s clean release, while dense hardwoods (oak, hickory) benefit from conventional’s extra hinge. Extremely leaning trees (over 15 degrees) require the Humboldt regardless of species. Always assess crown asymmetry—trees with heavy limbs on one side need the notch oriented to balance the load.

Common Notch Mistakes That Cause Failures

The most dangerous error is cutting the notch too deep—exceeding one-third of trunk diameter on trees under 24 inches removes too much hinge wood and causes the tree to split vertically (barber-chair). Another killer mistake is mismatching the top and bottom cuts, creating a step that redirects the fall 10-15 degrees off line. This happens when the bottom cut isn’t perfectly level or when the top cut angle is inconsistent.

Back cut placement errors account for 60% of felling accidents. Cutting the back cut level with the notch apex removes the hinge entirely, causing the tree to fall unpredictably. Conversely, cutting too high leaves insufficient hinge thickness and can cause the tree to sit back on the stump. Always measure from the notch apex, not the stump surface, since stumps often slope.

Tools and Setup for Perfect Notches

Your chainsaw bar length should be at least 2 inches longer than the tree diameter to ensure clean, full-depth cuts without overreaching. Use a 3/8-inch pitch chain with semi-chisel teeth for smooth notch cuts—full-chisel chains grab and diverge on hardwood fibers. Always carry a felling wedge for trees over 12 inches diameter to prevent pinching during the back cut.

Accuracy tools matter more than power. A 2-foot level ensures your bottom cut is perfectly horizontal, while a simple plastic protractor helps maintain consistent 45-70 degree angles. Mark your notch height with chalk before cutting—this prevents guessing when the sawdust starts flying. For trees over 30 inches, use a helper to sight the notch angles while you cut; visual parallax errors increase dramatically on large trunks.

What to Do Next

Before your next tree project, practice these notches on small diameter logs (6-8 inches) using the exact angles and depths described. Master the muscle memory of level bottom cuts and consistent top-cut angles in a low-stakes environment. For trees over 20 inches diameter or with any lean toward structures, hire a certified arborist—the cost of professional removal is negligible compared to roof repairs or liability claims.

If you decide to fell trees yourself, invest in quality tools first: a 20-inch bar saw with sharp semi-chisel chain, plastic wedges, and a level. Always establish two escape routes at 45-degree angles from the expected fall path, cleared of brush and obstacles. Remember that tree diameter, lean, and species determine notch choice—not personal preference or internet trends. When in doubt, the open notch remains the safest default for most situations. Always follow OSHA standards for tree care operations.