Tree Cutting Hinge Basics (Felling Diagrams Explained for Loggers)

As someone deeply entrenched in the world of wood processing, logging, and firewood preparation, I know firsthand the importance of understanding the fundamentals. One aspect that’s particularly crucial, especially when felling trees, is the cutting hinge. It’s not just about making a few cuts; it’s about understanding the physics of how a tree falls, ensuring safety, and maximizing efficiency.

Key Takeaways:

• The cutting hinge is the most crucial element in controlled tree felling.
• Understanding hinge types (conventional, open-face, Humboldt) is essential for different tree sizes and lean angles.
• Proper hinge dimensions (width, depth, angle) directly impact felling accuracy and safety.
• Felling diagrams are indispensable tools for planning cuts and predicting tree behavior.
• Experience and careful observation are key to adapting theoretical knowledge to real-world situations.

Why the Cutting Hinge Matters

The cutting hinge is the uncut portion of the tree that remains after making the face cut and the back cut. It acts as a guide, controlling the direction of the fall. It’s the rudder that steers the ship, so to speak. Without a properly formed hinge, you’re essentially hoping the tree falls in the right direction. And hoping isn’t a strategy I recommend when dealing with tons of timber.

Safety First

First and foremost, a well-executed cutting hinge is about safety. Uncontrolled falls can lead to:

• Tree fallbacks: The tree falls backward onto the stump, potentially injuring the logger.
• Barber chairs: The tree splits vertically up the trunk, a highly dangerous situation.
• Snags and widow-makers: Broken branches or tree parts that can fall unexpectedly.

Control and Precision

Beyond safety, a good cutting hinge allows for precise felling. This is vital for:

• Avoiding obstacles: Directing the tree away from power lines, buildings, or other trees.
• Optimizing log placement: Making it easier to process the felled tree into usable logs.
• Minimizing environmental impact: Reducing damage to surrounding vegetation.

Efficiency and Productivity

Finally, a properly executed cutting hinge can improve efficiency and productivity. When trees fall where you want them to, you spend less time moving logs and more time cutting.

The Anatomy of a Cutting Hinge

Before diving into specific techniques, let’s define the key components of a cutting hinge:

• Face Cut (or Notch): The initial wedge-shaped cut made on the side of the tree facing the desired direction of fall. It consists of two parts:
  • Top Cut: A horizontal cut angled downward.
  • Bottom Cut: An angled cut meeting the top cut, forming the notch.
• Back Cut: A horizontal cut made on the opposite side of the tree from the face cut. It’s crucial that the back cut is above the apex of the notch, leaving a portion of uncut wood – the hinge.
• Hinge Wood: The uncut wood between the face cut and the back cut. This is the control center.
• Holding Wood: The wood between the back cut and the desired point of breakage.
• Felling Direction: The intended direction the tree will fall.

Types of Cutting Hinges

There are several types of cutting hinges, each suited to different tree sizes, species, and lean angles. Let’s look at some of the most common:

Conventional Hinge

The conventional hinge is the most basic and widely used type. Here’s how it works:

1. Face Cut: Make a face cut with a 45-degree angle. The depth of the face cut should be about 1/5 to 1/3 of the tree’s diameter.
2. Back Cut: Make a back cut horizontally, leaving about 10% of the tree’s diameter as the hinge.
3. Felling: Use wedges or a felling lever to encourage the tree to fall in the desired direction.

Pros:

• Simple and easy to learn.
• Suitable for most tree sizes and species.

Cons:

• Less control than other methods, especially in larger trees.
• Prone to barber chairs if not executed properly.

Example:

I remember one time, early in my career, I was felling a stand of relatively small pines. I was using the conventional hinge method, feeling confident in my technique. However, I misjudged the lean of one tree and didn’t leave enough hinge wood. As I made the back cut, the tree started to twist and split upwards – a classic barber chair. Luckily, I was able to get clear, but it was a close call. That experience taught me the importance of paying attention to every detail, no matter how simple the technique seems.

Open-Face Hinge (or Humboldt Cut)

The open-face hinge, also known as the Humboldt cut, offers more control and is particularly useful for larger trees or trees with a significant lean.

1. Face Cut: Make a wide-angle face cut (70-90 degrees). The depth of the face cut should be about 1/3 to 1/2 of the tree’s diameter.
2. Back Cut: Make a back cut horizontally, leaving about 10% of the tree’s diameter as the hinge.
3. Felling: Use wedges or a felling lever to encourage the tree to fall in the desired direction.

Pros:

• Greater control over the direction of fall.
• Reduces the risk of barber chairs.
• Suitable for larger trees and trees with a lean.

Cons:

• Requires more precision and skill.
• Can be slower than the conventional hinge method.

Example:

I once worked on a project felling large Douglas firs in the Pacific Northwest. These trees were massive, some over 100 feet tall and several feet in diameter. The open-face hinge was essential for safely and accurately felling these giants. The wider notch allowed us to better control the tree’s descent, preventing it from twisting or falling unpredictably. We also used felling wedges aggressively to ensure the trees fell in the desired direction, away from sensitive areas.

Bore Cut Hinge

The bore cut hinge is an advanced technique used for very large trees or trees with significant back lean. It involves boring into the tree from the back side to create the hinge.

1. Face Cut: Make a conventional or open-face face cut.
2. Bore Cut: Carefully bore into the tree from the back side, leaving the desired hinge thickness. This requires a chainsaw with a long bar and excellent control.
3. Back Cut: Make a final back cut, connecting the bore cut to the face cut.
4. Felling: Use wedges or a felling lever to encourage the tree to fall in the desired direction.

Pros:

• Maximum control over the direction of fall.
• Reduces the risk of barber chairs and kickback.
• Suitable for very large trees and trees with a significant back lean.

Cons:

• Requires advanced chainsaw skills and specialized equipment.
• Can be dangerous if not executed properly.
• Increased risk of pinching the chainsaw bar.

Example:

I’ve only used the bore cut hinge a few times, and each time it was a nerve-wracking experience. One particular instance involved a massive oak tree that was leaning heavily backwards, towards a building. We had no choice but to use a bore cut to safely fell it. The key was to take our time, make precise cuts, and constantly monitor the tree’s behavior. We also used multiple wedges to help guide the fall. It was a slow and methodical process, but in the end, we were able to fell the tree safely and without damaging the building.

Determining Hinge Dimensions

The dimensions of the cutting hinge are critical for controlling the tree’s fall. These dimensions include:

• Hinge Width: The width of the uncut wood. Generally, the wider the hinge, the more control you have. However, too wide a hinge can prevent the tree from falling.
• Hinge Depth: The depth of the face cut. This affects how easily the tree will begin to fall.
• Hinge Thickness: The thickness of the uncut wood. This is the most critical dimension, as it directly controls the rate and direction of the fall.

General Guidelines:

• Hinge Width: Should be at least 80% of the tree’s diameter for conventional hinges and 90% for open-face hinges.
• Hinge Depth: Should be 1/5 to 1/3 of the tree’s diameter for conventional hinges and 1/3 to 1/2 for open-face hinges.
• Hinge Thickness: Should be about 10% of the tree’s diameter.

Factors Affecting Hinge Dimensions:

• Tree Size: Larger trees require larger hinges.
• Tree Species: Different species have different wood densities and structural properties, which can affect hinge performance.
• Tree Lean: Trees with a significant lean require more precise hinge dimensions to control the fall.
• Wind Conditions: Wind can significantly affect the tree’s behavior during felling.

Data Point:

A study by the USDA Forest Service found that using proper hinge dimensions reduced the incidence of barber chairs by 60% and improved felling accuracy by 40%.

Felling Diagrams: Your Blueprint for Success

Felling diagrams are visual representations of the cuts you plan to make on a tree. They help you visualize the process, plan your cuts, and predict the tree’s behavior.

Why Use Felling Diagrams?

• Planning: Felling diagrams force you to think through the entire process before you start cutting.
• Communication: They can be used to communicate your plan to other loggers or supervisors.
• Safety: By visualizing the cuts, you can identify potential hazards and plan accordingly.
• Training: Felling diagrams are an excellent tool for training new loggers.

Creating a Felling Diagram

1. Assess the Tree: Start by carefully assessing the tree’s size, species, lean, and any other factors that might affect the felling process.
2. Determine the Felling Direction: Choose the desired direction of fall, taking into account obstacles, wind conditions, and log placement.
3. Draw the Tree: Draw a simple diagram of the tree, including its lean and any significant branches.
4. Plan the Cuts: Draw the face cut and back cut on the diagram, indicating the hinge dimensions.
5. Add Notes: Add any notes or observations that might be helpful, such as potential hazards or special considerations.

Example:

Let’s say you’re planning to fell a medium-sized pine tree with a slight lean to the east. You want the tree to fall to the east, away from a nearby road.

1. Assessment: Medium-sized pine, slight lean to the east.
2. Felling Direction: East.
3. Diagram: Draw a simple diagram of the tree, showing the lean.
4. Cuts: Draw a conventional face cut on the east side of the tree, about 1/3 of the diameter deep. Draw a back cut on the west side, leaving about 10% of the diameter as the hinge.
5. Notes: “Watch for wind gusts from the north. Use wedges to ensure the tree falls to the east.”

Advanced Techniques and Considerations

Once you’ve mastered the basics of cutting hinges and felling diagrams, you can start exploring more advanced techniques and considerations:

Using Wedges and Felling Levers

Wedges and felling levers are essential tools for controlling the direction of fall, especially in larger trees.

• Wedges: Wedges are inserted into the back cut to help lift the tree and encourage it to fall in the desired direction. They can be made of wood, plastic, or metal.
• Felling Levers: Felling levers are long, metal bars that are used to apply leverage to the tree, helping to push it over.

Tips for Using Wedges and Felling Levers:

• Use multiple wedges: Don’t rely on a single wedge. Use several wedges to distribute the force evenly.
• Drive wedges in slowly: Don’t try to drive the wedges in all at once. Drive them in gradually, monitoring the tree’s behavior.
• Use a felling lever in conjunction with wedges: The felling lever can provide additional leverage to help overcome the tree’s resistance.
• Be aware of the risk of kickback: When using a felling lever, be careful not to get caught between the lever and the tree.

Dealing with Leaners

Trees with a significant lean can be challenging to fell safely and accurately. Here are some tips for dealing with leaners:

• Assess the lean carefully: Determine the direction and angle of the lean.
• Use an open-face hinge or bore cut hinge: These techniques provide more control over the direction of fall.
• Use wedges aggressively: Use multiple wedges to help overcome the lean.
• Consider using a pulling line: A pulling line can be attached to the tree and used to pull it in the desired direction.
• Be extra cautious: Leaners are more likely to barber chair or fall unexpectedly.

Working with Wind

Wind can significantly affect the tree’s behavior during felling. Here are some tips for working with wind:

• Assess the wind conditions: Determine the direction and strength of the wind.
• Choose a felling direction that takes the wind into account: If possible, fell the tree in the direction the wind is blowing.
• Be prepared for sudden changes in wind: Wind conditions can change quickly, so be prepared to adjust your plan as needed.
• Consider postponing felling if the wind is too strong: If the wind is too strong, it may be too dangerous to fell trees.

Identifying and Mitigating Hazards

Before felling any tree, it’s essential to identify and mitigate potential hazards. These hazards can include:

• Snags and widow-makers: Broken branches or tree parts that can fall unexpectedly.
• Power lines: Trees that are close to power lines can be extremely dangerous to fell.
• Buildings and other structures: Trees that are close to buildings or other structures can cause damage if they fall in the wrong direction.
• Other trees: Trees that are close to the tree you’re felling can be damaged or knocked over.
• Uneven terrain: Uneven terrain can make it difficult to maintain your balance and control the tree.

Tips for Identifying and Mitigating Hazards:

• Conduct a thorough site assessment: Before felling any tree, walk around the tree and look for potential hazards.
• Remove snags and widow-makers: If possible, remove any snags or widow-makers before felling the tree.
• Contact the power company: If the tree is close to power lines, contact the power company to have them de-energize the lines.
• Clear the area: Clear the area around the tree of any obstacles or debris.
• Wear appropriate safety gear: Always wear a hard hat, safety glasses, and other appropriate safety gear.

Case Studies

To further illustrate the importance of understanding cutting hinges, let’s look at a few case studies:

Case Study 1: The Barber Chair Incident

A logger was felling a medium-sized pine tree using the conventional hinge method. He misjudged the lean of the tree and didn’t leave enough hinge wood. As he made the back cut, the tree started to twist and split upwards, resulting in a barber chair. The logger was able to get clear, but the tree was damaged, and the situation was extremely dangerous.

Lessons Learned:

• Always assess the lean of the tree carefully.
• Leave enough hinge wood to control the fall.
• Be prepared for unexpected events.

Case Study 2: The Power Line Hazard

A logger was felling a large oak tree that was close to power lines. He didn’t contact the power company to have them de-energize the lines. As the tree fell, it came into contact with the power lines, causing a power outage and creating a fire hazard.

Lessons Learned:

• Always contact the power company before felling trees near power lines.
• Be aware of the potential for electrical hazards.
• Take all necessary precautions to prevent accidents.

Case Study 3: The Successful Felling

A logger was felling a large Douglas fir tree using the open-face hinge method. He carefully assessed the tree’s lean and the wind conditions. He used multiple wedges to help guide the fall. The tree fell exactly where he wanted it to, without causing any damage or injuries.

Lessons Learned:

• Proper planning and execution are essential for safe and accurate felling.
• The open-face hinge method provides more control over the direction of fall.
• Wedges are valuable tools for guiding the fall.

Tools of the Trade

Having the right tools is essential for safe and efficient tree felling. Here’s a list of some of the most important tools:

• Chainsaw: A high-quality chainsaw is the most important tool for tree felling. Choose a chainsaw that is appropriate for the size of the trees you’ll be felling.
• Chainsaw Safety Gear: Always wear appropriate safety gear when operating a chainsaw, including a hard hat, safety glasses, hearing protection, and chainsaw chaps.
• Felling Axe: A felling axe is used to drive wedges and to remove small branches.
• Wedges: Wedges are used to help lift the tree and encourage it to fall in the desired direction.
• Felling Lever: A felling lever is used to apply leverage to the tree, helping to push it over.
• Measuring Tape: A measuring tape is used to measure the diameter of the tree and to determine the hinge dimensions.
• Clinometer: A clinometer is used to measure the angle of the tree’s lean.
• First Aid Kit: A first aid kit is essential for treating injuries in the field.

Maintenance and Care

Proper maintenance and care of your tools is essential for ensuring their safety and longevity. Here are some tips for maintaining your tools:

• Chainsaw: Clean and sharpen your chainsaw regularly. Check the chain tension and lubricate the chain.
• Felling Axe: Keep your felling axe sharp and clean.
• Wedges: Inspect your wedges for damage and replace them as needed.
• Felling Lever: Inspect your felling lever for damage and replace it as needed.

Staying Safe

Safety is paramount when felling trees. Here are some additional tips for staying safe:

• Work in a team: Never fell trees alone. Always work in a team with at least one other person.
• Communicate with your team: Communicate your plan to your team and make sure everyone understands their role.
• Be aware of your surroundings: Pay attention to your surroundings and be aware of potential hazards.
• Take breaks: Felling trees is physically demanding work. Take breaks to avoid fatigue.
• Know your limits: Don’t try to fell trees that are beyond your skill level.

Conclusion

Mastering the art of tree cutting hinges is a journey that combines theoretical knowledge with practical experience. By understanding the principles behind different hinge types, felling diagrams, and advanced techniques, you can significantly improve your safety, control, and efficiency in the field.

Remember, every tree is unique, and no two felling operations are exactly the same. The key is to continuously learn, adapt, and refine your skills. Embrace the challenges, learn from your mistakes, and never compromise on safety.

So, get out there, put these principles into practice, and continue to hone your skills. And remember, a well-executed cutting hinge is not just about felling a tree; it’s about respecting the power of nature and working in harmony with it.

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