A tree burl is a type of cancerous growth on a tree. From the outside, maple burls look like bulbous or tumorous growths protruding from the tree. Inside, a maple burl features irregular and unique patterns of growth. These irregular patterns are highly valued. Maple burl is used to make table tops and a variety of other wood objects. Most burls are harvested from trees that have fallen over naturally.
Cut the branch containing the burl at its base, just above the swollen branch collar where the branch meets the trunk of the tree. If the branch is small enough, have a partner support the branch as you cut to prevent it from falling. Burls are fracture prone and may break when they hit the ground. If the branch is very large, cut the branch off a minimum of six inches beyond the burl with a hand saw. Keep as much of the branch attached as possible.
Locate a spot on the trunk that is opposite the direction that you want the tree to fall if the burl is in the trunk. If at all possible, fell the tree so that it falls away from the burl. Large tree burls are fracture prone and the impact of the tree can split or shatter a burl.
Make a 45-degree-angle downward cut that extends into the trunk at a distance equal to roughly one-third of the diameter of the tree's trunk. Make a second cut four or five inches below the bottom of the first cut. Angle this cut upward at a 45 degree angle so that it meets the bottom of the first cut and removes a wedge out of the trunk. Make a third felling cut behind the removed wedge three to four inches above the wedge's hinge. Stop cutting when the tree begins to fall.
Move away from the tree quickly. Keep in mind that heavy burls can make a falling tree unpredictable. The weight of the burl may make the tree fall to one side or the other or kick back and fall toward the felling cut. This unpredictability is dangerous when dealing with large maple trees that can range from 30 to 145 feet in height depending on the age and species of the tree. If you are not an experienced tree cutter, consider leaving the job to a professional.
Cut away the section of the tree trunk that contains the burl. Make each cut at least 6 inches beyond the burl on each side. The buffer wood keeps the burl from drying out before it is ready to be worked and provides a surface from which to dry, mount and work the burl. If possible, leave as much healthy trunk material connected as you can manage. The healthy material may be used in the finished piece to add contrast or support.
Cut away part of the trunk if the trunk and burl section is too large to easily transport. Cut away the back section of the trunk that does not contain burled wood. Cut just enough to reduce the trunk and burl to a manageable size. If you cut too close to the burl, you may remove some of the valuable wood.
Cut the burl into sections or slabs, depending on its intended use, if it is still too large. Most maple burls are well under 100 pounds, but some may be quite large. Again, only cut if and as much as necessary. Cutting into a burl decreases its value and dries out the wood. If at all possible, pick either step three or step four to reduce the size of your burl. Leave as much unburled wood on the harvest as possible.