Bore Cutting With Long Bars (Field Mechanics)
A bore cut uses the nose of a chainsaw bar to make a controlled cut into sound wood. With a long bar, the saw must be an approved match for the bar and chain, and the operator must be trained in the technique. Long bars raise torque, heat, and kickback concerns; they do not make an unsafe felling plan workable.
A long bar can help reach through a large stem, but it also gives you more bar nose to manage and places extra demands on the saw. That matters most during a bore cut, where the bar nose enters the wood and the upper quadrant can cause rapid kickback if it contacts the stem.
I use bore cutting only as part of a planned tree operation, not as a shortcut around poor access or an uncertain felling direction. If you are learning the technique, get hands-on instruction from a qualified chainsaw trainer. A written guide cannot teach you to read a moving stem or recover from a kickback.
Equipment Setup and Safety Preparation
A safe setup starts with a saw, bar, sprocket, and chain combination the saw maker approves. There is no safe universal bar-length-to-engine-displacement ratio. Check the manual, the tree-work plan, and your training before deciding whether the equipment and task are suitable.
Confirm the saw and cutting equipment
Match the chain’s pitch, gauge, and drive-link count to the bar and sprocket. A 3/8-inch pitch and .050-inch gauge combination is common, but it is not a default. Use the exact parts listed for your saw and bar. Do not fit a longer bar merely because the engine seems powerful enough.
Check chain tension and inspect the bar rails, fasteners, chain catcher, chain brake, and throttle lockout. Confirm the chain moves freely by hand only with the engine off and the brake released, following the manual’s procedure. A damaged brake, loose part, or uneven bar rail is a stop-work issue.
Plan the tree operation before starting
Assess lean, dead or broken limbs, decay, wind, nearby structures, and the intended drop zone. Identify escape routes and keep bystanders outside the work area. Establish a way to communicate with anyone assisting you. If the tree has defects, a heavy lean, overhead hazards, or an uncertain fall path, bring in a qualified tree professional.
Wear a helmet, face and eye protection, hearing protection, chainsaw chaps, gloves, and suitable boots. Use the saw maker’s starting procedure on stable ground with the chain brake engaged. Warm the saw, then check idle, throttle return, and oil delivery. Never start or run the saw above shoulder height.
Field Bore-Cutting Operation
A bore cut is a controlled plunge of the bar nose into wood to create an internal kerf. In a felling cut, it may help form a hinge while leaving planned holding wood. It is not a general-purpose cut, and it should be used only by someone trained to control the nose and protect the hinge.
Control the bar nose
Before cutting, establish the planned face cut and the hinge dimensions for the tree and site. Release the chain brake only when ready to cut. Start the bore with the lower quadrant of the bar nose, keeping the upper quadrant clear of unintended contact. Contact between that upper quadrant and wood can trigger fast rotational kickback.
Keep a secure stance and a two-handed grip. Advance steadily and keep the bar aligned with the planned kerf. Do not force the saw if the chain slows, the bar binds, or the kerf begins to close. Stop if the stem moves unexpectedly, starts to split, or the cut drifts from the plan. Reassess from a safe position rather than trying to correct a compromised cut.
Preserve the planned hinge and holding wood. Cutting through them can remove control of the tree’s movement; a splitting stem can also barber-chair, or split upward along the trunk. If either condition appears, abandon the cut and move away on the prepared route if the tree begins to move. Never continue simply to finish a cut.
Field scenarios: what changes the decision?
These are practical scenarios, not reports of specific jobs. They show how conditions affect the choice to bore cut with a long bar.
- Sound stem, clear drop zone, approved saw setup: A trained operator may use the planned bore-cut sequence if the tree assessment and felling plan support it. The hinge and holding wood still need to remain intact.
- Uncertain decay or a large crack: Do not assume a bore will make the tree safer. Hidden defects can change how the stem holds and moves. Stop and seek an arborist or qualified feller.
- Bar binds or the kerf closes: Stop cutting. Do not rev or push harder to free the chain. Follow the work plan for a safe response; if the stem is moving or splitting, retreat.
- Long bar exceeds approved saw setup: Do not proceed, even if the bar reaches the planned cut. Use an approved combination and suitable equipment, or have a qualified operator handle the work.
| Field check | What to verify | Stop or reassess when |
|---|---|---|
| Saw compatibility | Manual approves the bar, chain, and sprocket combination | Any component is unapproved or the match is uncertain |
| Chain condition | Correct tension, sharp cutters, sound links | Chain is damaged, dull, or binds |
| Bar lubrication | Correct bar-and-chain oil; oil delivery confirmed | Oil flow is absent or uncertain |
| Tree plan | Lean, defects, drop zone, escape route, hinge plan | Movement, splitting, or cut deviation occurs |
| Operator position | Stable footing, two-handed grip, below-shoulder work | You cannot control the bar or maintain a safe stance |
Key takeaway: If equipment, tree condition, or operator training is uncertain, do not bore cut. A longer bar does not widen the margin for error.
Maintenance, Sharpening, and Tuning
A sharp, correctly adjusted chain cuts with less strain than a dull or poorly matched one. Maintenance does not remove the risks of a long bar, but it helps prevent avoidable binding, excess heat, and loss of cutting control. Follow the saw and chain makers’ service instructions rather than using one setting for every setup.
Set depth gauges, also called rakers, to the chain maker’s specification. A .025-inch (0.63 mm) setting is a common reference, not a universal target. The correct setting depends on the chain and its intended use. If you are unsure, have a trained service provider check it.
Use the fuel mix and oil grade stated in the saw manual. A 50:1 fuel ratio is common, not universal; never use straight gasoline in a two-stroke saw. Use the specified bar-and-chain oil, and check delivery before work. Oil viscosity, flow adjustment, and seasonal grade depend on the model and temperature.
For engine speed, use the model’s stated idle and maximum no-load RPM and its tachometer procedure. Do not tune by sound or exceed the manual’s limit. If the saw will not idle, return to idle after throttle release, or run within specified limits, stop and have it serviced.
Shutdown, Storage, and Seasonal Care
A proper shutdown protects the operator and helps catch damage before the next cut. Engage the chain brake and shut down the saw as its manual directs. Let it cool in a safe place before cleaning or transport. Never leave a running or hot saw where fuel, dry debris, or people could be exposed to it.
After use, clean the air intake and sprocket cover, then clear debris from the bar groove and oil ports. Inspect the bar, chain, brake, and fasteners for wear or damage. Store the saw and fuel as the manufacturer directs, away from heat and ignition sources. For seasonal changes, follow the manual on fuel, oil, and storage steps rather than guessing at a different mix or lubricant.
Conclusion: Know When Not to Bore
Long-bar bore cutting is a specialized method, not a basic DIY felling step. The safe decision depends on an approved saw setup, a sound and understood tree, a written or clearly planned sequence, and an operator trained to manage the bar nose and preserve the hinge. If one of those conditions is missing, stop and call a qualified professional.
Apply current ANSI Z133 requirements and employer procedures for arboricultural work. OSHA 29 CFR 1910.266 is a logging standard; whether it applies depends on the work and jurisdiction. It does not replace arboricultural training or other applicable tree-work rules.
Frequently Asked Questions
What is a bore cut with a chainsaw?
It is a controlled plunge of the bar nose into wood to form an internal kerf. In felling, a trained operator may use it as part of a planned cut while preserving hinge and holding wood.
Can any chainsaw use a long bar?
No. Use only a bar, chain, and sprocket combination approved for the saw. Do not choose bar length based on engine size alone; there is no universal safe ratio.
Which part of the bar nose starts a bore cut?
The lower quadrant is used to initiate the bore. Keep the upper quadrant clear of unintended contact because it can cause rapid rotational kickback.
Is a 3/8-inch pitch and .050-inch gauge chain always correct?
No. That is one common combination. Check the saw and bar specifications for the correct pitch, gauge, drive-link count, and sprocket.
Is 50:1 the correct fuel mix for every two-stroke saw?
No. Use the ratio and oil grade in the saw manual. Fifty-to-one is common, but not universal; never run a two-stroke saw on straight gasoline.
What should I do if the bar binds during a bore cut?
Stop. Do not force or rev the saw to free it. Reassess from a safe position and follow the work plan. If the tree moves or begins to split, retreat on the prepared route.
Can I set every chain’s depth gauges to .025 inch?
No. That is only a common reference value. Set depth gauges to the chain maker’s specification for the chain and application.
When should I hire a professional?
Hire a qualified tree professional when the tree is defective, leaning unpredictably, near people or property, or beyond your training. Do the same if you cannot confirm the equipment setup or make a safe felling plan.
(This article was written by one of our staff writers, Julian Barrett. Visit our Meet the Team page.)
