The Bore Cut...
By Tim Ard
Bore cut - a chain saw technique, beginning with the lower tip of the guide bar, to insert a back cut through the tree trunk establishing a controlling hinge and a holding back strap.
I can tell you over and over about the times I begin a training or demonstration session and mention the bore cut and attendees say, "what do you mean, bore cut"? Not many people really understand what it is and what its advantages and disadvantages are. It's not a technique to use on every tree but when a plan calls for some of the situations below, the bore cut excels.
10 "off the top" boring situations:
Wedging trees with a diameter less than 15"
One thing that is hard to do in a sawyers plan is to cut a tree in the twelve to sixteen inch diameter range without a rope pulling or a tractor pushing. The reason I feel, it is hard to begin a back cut on this size tree and insert a wedge in the back cut before the tree starts to lean on the saw.
The bore cut can be used in this case to create a back cut, establishing the desired hinge and holding the tree stable by leaving wood holding in the back. In that created slot, removing the saw from the kerf, a wedge can be placed in the opening. Cut the back holding wood (back strap) and lift the tree by driving the wedge.
Removing pulling fiber and log quality issues
A bore cut can relieve most all issues of pulled fiber from the log and stump.
Falling trees with greater diameter than the guide bar length
Larger diameter trees can be felled in two to three cuts utilizing bore cuts. Two to three times the guide bar length can be achieved. Cut half of the diameter and then the other from the inside out.
Controlling the release of the tree fall
Using a bore cut, a back strap of wood fiber can be left holding a heavy forward leaning tree until the sawyer is ready to release the strap.
Reducing fiber pull and "barber chair" on heavy leaner's
Heavy forward leans often create hazardous trunk splitting that can be virtually eliminated with a bore cut and back strap techniques.
Checking for bad fiber and or hollow trunks
Sometimes better than an increment boring tool, simply use a bore cut to discover if a tree trunk is hollow or slightly rotted.
Cutting in steep or questionable terrain
It's not always easy to retain stable footing when walking in steep or slick terrain- let alone when sawing. Bore cuts can offer a more stable cutting position for the sawyer. Retreat paths can be more confident and better planned.
Maximizing escape route distance
Back strap release, created by a bore cut, can offer the sawyer an extra three to five feet in escape reaction time and distance.
Establishing worksite reaction time
In tree work near roadways or populated areas the bore cut can offer greater safety. When a back cut from the rear of the trunk is started, the sawyer is committed. If someone or something enters the work area often there is no stopping. With the bore cut and back strap release the sawyer has time to do a final check of the area before the tree is released.
Reaction time from overhead hazards
When vines and overhead "widow-makers" are present, an extra few seconds and a few feet in retreat can offer needed reaction time. This can be something to reduce struck-bye's in felling operations.
Before using the bore cut technique I strongly suggest you seek hands-on training in the technique. You should have a thorough understanding of the reactive forces of the chain saw. Always use proper PPE required by your employer or recommended by your chain saw manufacturer. Read and thoroughly understand your saw’s operator manual.
The Bore Cut is sometimes referenced as the Plunge Cut.
Please contact Forest Applications Training, Inc. for more info and specialized training on use of the Bore Cut.
The Bore Cut.doc 31 August 2009