By Michael Tain
The chain saw is, without question, one of the most valuable tools that climbing arborists have in their arsenal. This small, relatively light piece of equipment enables tree care professionals to fell, prune and remove trees in a highly efficient manner in a wide variety of locations, situations and positions without the large energy expenditure required of hand saws or the crosscuts and axes of the past. Yet, as with almost every tool, method or technique that tree crews might use, there are different situations that will influence and dictate the efficient, safe and appropriate use of the chain saw.
A mismatch cut on a vertical piece or spar; note that the mismatched cuts overlap or bypass one another. The distance between cuts will vary with diameter and species.
The completion of a properly executed spar mismatch cut in which the climber is able to put their chain saw away, and, using both hands, snap off and throw the severed piece of wood to the desired landing area.
A mismatch cut on a horizontal branch (as shown from above) in which the cuts are to either side of the branch, not the top and bottom. The distance between cuts will vary with diameter and species. Larger diameters and species with stronger wood will require the cuts be closer together, while smaller diameters and species with weaker wood will need to be further apart.
The completion of a horizontal branch mismatch cut; note the importance of the cuts overlapping or bypassing one another, as this is typically where the piece will separate.
All photos provided by Michael TainOne of the scenarios that has the most influence on chain saw use is when elevated — whether it is climbing or when working from an aerial lift. Both of these locations put the chain saw operator in a place of isolation, separated from their fellow crew members on the ground and the help or assistance they might be able to provide in the event of an emergency. Cutting with a chain saw aloft also limits the operator’s escape routes in comparison to cutting on the ground — there are simply not that many safe places/directions that the operator can escape to if needed. Additionally, operating a chain saw while aloft, particularly during climbing operations, exposes the operator to additional dangers and challenges in regard to stable body positioning and the fact that they are suspended aloft by a system of ropes and cordages that can easily be cut in a moment of inattention. Although aerial chain saw use does present unique challenges and dangers in comparison to its ground operation, there are a variety of guidelines, methods and techniques that can not only make the use of this tool aloft efficient, but also safe.
Chain saws are meant to be operated with both hands, whether on the ground or in the air. Operators, regardless of experience, knowledge and strength, simply do not have the control required when operating a saw with one hand; and should they use this technique consistently are “rolling the dice,” with the likely end result being a catastrophic accident or injury. Standards require that persons operating a chain saw aloft be secured in two ways (i.e., a work positioning lanyard and climbing line) in the event the saw severs one of these systems. The advent and use of extremely sharp hand saws also make lanyard/secondary system use a good idea while cutting with them, though it is not yet required by standards. Operators using a wire-cored lanyard should not consider it chain saw proof; and should realize that when under load a running chain saw can, and will, cut through it. Chain saw-resistant lower body protection, chaps or pants are not currently required nationally by existing standards for aerial chain saw use. However, they are an excellent idea, and are highly recommended when operating a chain saw aloft.
A key consideration when operating a chain saw, whether aloft or on the ground, is to whenever possible avoid being in the line of travel if the saw “kicks back.” This is of particular importance when using the saw while climbing or from an aerial lift, as the operator is isolated from the rest of the crew’s assistance in event of a chain saw cut. Additionally operators working aloft will have limited or suspect footing to deal with the force and power of a “kickback,” making contact with themselves or their climbing system much more likely. Knowing and recognizing the causes of “kickback” and avoiding them will eliminate the majority of the risk of it occurring. However, putting some thought into the positioning of the chain saw in relation to the operator while cutting can radically limit the possibility of a “kickback” striking the operator or his/her climbing system. For example, cutting with the bottom of the bar with the chain saw held horizontally directly in front of the operator exposes the whole upper body and climbing system to laceration in the event of a “kickback.” A better option would be to reposition more to the side of the piece to be cut, and use the top of the bar, thereby directing any “kickback” that might occur out and away from the operator.
Hand saw use
An excellent, though often neglected, tool during aerial chain saw use is the hand saw. The majority of cuts can be carried out to just before completion with the chain saw, then finished with the hand saw. This allows the climbing arborist to avoid dancing in the air from the resulting branch/top/piece removal forces with a running chain saw in his or her hands. The use of a hand saw with a straight blade will allow users to “thin” the hinge in a felling cut evenly while aloft, unlike a curved blade that will remove material from either end of the hinge leaving a thick portion in the middle.
Mismatch or snap cut
The mismatch or snap cut is an excellent technique when cutting aloft. It allows the operator to sever the piece while leaving it in place, safely stow the chain saw away, and snap the piece off to throw it to the desired landing zone — all while avoiding one-handed chain saw operation. This technique can be used for either horizontal branches or vertical spars, although the location of the cuts will vary with orientation. Two staggered cuts are made with the chain saw on either side of the piece to be removed, and the distance between the cuts will vary with species and size. For example, more brittle wood and smaller diameters will require the cuts be made further apart, while stronger woods and larger diameters will necessitate the cuts are closer together. The cuts should overlap each other in the middle of the piece (as can be seen from the accompanying photographs). The piece is now technically severed, but the remaining fiber in the vertical plane — if the cut has been done correctly — will keep the piece in place until the operator can stow the saw, and snap the piece off.
Jump or drop cut
The classic jump or drop cut that has been part of climbing arborists’ repertoires for generations requires a slightly different method when being performed with a chain saw. Traditionally carried out with a hand saw, it is illustrated in many books/guidelines as consisting of three cuts: one under the branch nearer to the trunk; one on top of the branch away from the trunk and undercut to separate the branch; and a final cut to remove the stub. Although this works very well with a hand saw, it can have unfortunate consequences when carried out with a chain saw. The mismatched or staggered kerfs of the first and second cut can grab or “snatch” the chain of the saw as the branch separates, pulling the saw, along with the operator, toward the ground. However, this action is easily prevented by completing the second cut directly above the first or undercut, freeing the branch to drop fairly level to the ground without grabbing the chain or bar of the saw.
The use of notches when aloft is quite advantageous when tops, branches or pieces of wood need to be felled in a particular direction or spot. Operators should use the same process to determine lean, size of hinge, desired direction, etc., that they would use during ground felling operations. The use of open-face notches is recommended, though climbers should always consider what arc of movement they need the piece to go through, and adjust the angle of the face notch accordingly. For example, when removing a top that is straight up and down, a notch at an angle of greater than 90 degrees will cause the hinge to continue to function as the top heads to the ground, thereby increasing the movement of the rest of the tree (with possibly undesirable consequences). A good guideline for top removal is to open the notch to an angle that will cause it to close when the top is almost parallel, or completely parallel, to the ground — thus lessening forward movement of the remaining tree. Notches may also be used when tip tying and lifting branches in rigging operations — after all, the operator is now felling a branch upward instead of down. The size of the notch is determined by making one cut parallel to the ground/horizon and the other perpendicular to the branch orientation. This will form a notch that will close when the branch is vertical; assuming the block lifting the branch is located as close to directly above the face notch as possible. Closing the notch slightly will lessen the likelihood that the climber will have to come back in and sever the still-attached hinge to free the branch.
Using a chain saw when aloft, whether climbing or operating an aerial lift, is more complex than operating one on the ground. Yet, tree care professionals who understand the basic reactive forces, safety features, and operational techniques of a chain saw are well on their way to safe and efficient pruning, cutting and removal in the air.
Michael (House) Tain is a contract climber, splicer, educator and writer associated with North American Training Solutions www.northamericantrainingsolutions.com and Arbor Canada Training and Education www.arborcanada.com. He is currently located in Lancaster, Ky., and can be reached via e-mail at firstname.lastname@example.org