Using a pruning or pole saw to remove a large or long branch from a tree can be detrimental to both the arborist and the tree due to the heavy weight of the limb. Failing to properly account for this weight before making an intended cut will almost always tear living tissue from a tree, causing unwanted, and sometimes permanent, damage. Jump cuts allow the limb being pruned to jump away from both the tree and the groomer, preventing potential injury to either one. This type of cut should be used even when handling branches that are thin or low to the ground, as any weighted limb can impact the tree's health and the home gardener's safety.
Limbing Heavy Branches
Any limb that is too thick for hand pruners or loppers needs a saw to be properly cut and removed. And wood this thick is structural—like the beams in a house—bearing important weight and making the process of removal tricky.
As a general rule of thumb, a branch is considered dangerous to remove if it's large enough that you would not be capable of holding it with one hand. This rule also applies to limbs that are too high to reach when standing on the ground or long enough that the torque of the branch's weight would rotate your grip, once removed. With practice, you’ll learn what types of branches are too heavy to hold in place with your non-cutting hand. But when in doubt, jump-cutting is the recommended tactic.
Removing Weight with Preliminary Cuts
Cutting a large limb in a single pruning is a two-phase process. The first phase requires making cuts in the limb of the tree (just above a node) to remove excess weight from its end. Many cuts may be needed to remove the extra weight before making your final pruning cut.
Once you've finished your preliminary cuts, the piece of the branch that remains stuck to the tree should be much smaller and lighter. To assure this, allow a one-foot of buffer distance between your final preliminary cut and your limbing cut. That way, when the wood hinges and peels, it will only damage the parts that will later be removed. This procedure also makes the limb more manageable with your one free hand.
Making a Jump Cut
Once you’ve removed nearly all of the branch's weight, you can then use your saw to make a final cut where you want it. But in order to be perfectly safe, precede your last cut with a jump cut. A jump cut prevents the formation of a dangerous wood hinge. Instead of the branch swinging, the jump cut makes it “jump” away from the tree.
To make a jump cut, choose a spot on your branch a few inches away from your final cut and cut up from the bottom (or on the opposite side of your final cut), creating a slice that's 1/4 of the width of the limb. This can be an awkward cut to make, given your positioning, but it should be completed quickly. Next, make your final cut from the top down or opposite the jump cut. When the branch pulls away, it will fall vertically without bending, swinging, or tearing your tree.
Hazards of Tree Limbing
If you decide to limb your tree without making preliminary cuts, the branch will start to bend down as it loses support. Eventually, you'll have just a small hinge left which can suddenly snap or break violently, causing a wound on your tree. This technique can also create a reaction that blows shards of wood into your face or causes you to be thrown off-kilter, resulting in a fall. Additionally, a bad cut can cause wood to swing and fall unpredictably, potentially falling onto your house or severely injuring a person standing below.