A compressed view of the process for creating a bow tie key joint in a live edge top for a bench, using the Festool OF 1400 plunge router and HEPA dust extractor system
1 Comment
Burls can be safely removed from standing timber without risking adverse effects to the health of the tree. This particular harvest came from a stand of trees on farmland near the Conestoga Creek in Lancaster County, PA After peeling the bark from the outside surface of the bark, a flat section is created on what will become the bottom of the finished product. I then glue a block of wood onto this surface, which allows the burl to be firmly secured in my Rockwell Jawhorse workstation throughout the carving process. I start by removing as much wood as possible with a chainsaw, while taking care to not cut too deep at any point, thereby avoiding the risk of cutting through the what will be the outside of the bowl. I use a Stihl model designed for professional arborists, as it is lightweight yet well built, and allows a higher level of control than a normal chainsaw.
I prefer doing as much of the carving as possible while the wood is still "green," as it becomes much more difficult after the wood has dried. The challenge with this approach is avoiding the cracking and/or checking that would normally occur during the drying process. While the nature of the growth patterns present in a burl make it less susceptible to checking, it does not entirely rule out the possibility. So, the first step in avoiding checking is to carve away as much wood as possible, creating as thin a wall as possible. This reduces the amount of pressure that results from the drying process, thereby reducing the possibility of checking. The second step is to enclose the carved bowl in several paper shopping bags, as this creates a self-regulating micro climate on the inside that is nearly ideal for drying. Not that these two steps completely eliminate the possibility of a piece being ruined by checking during the drying process, but they go a long way towards reducing the possibility (not to mention being a great way of reusing the Ten Thousand Villages shopping bags that end up in the recycling bins). I will likely need to allow at least six - eight weeks of time for this bowl before it has dried enough to allow the final sanding & finishing processes.
In order to enhance the aesthetic effect, I prefer to select a wood for the bow tie keys that has a contrasting color. In this particular instance, since the locust used for the top has a warm golden color, I selected black walnut for the bow tie keys. After cutting several different bow ties using a bandsaw, I selected two having the desired size and proportions, and then determined the best placement along the check. Holding the keys firmly in place, the outline is drawn onto the top. The next step is to make a shallow cut in the surface of the locust, using a sharp knife following the drawn outline of the bow tie. I find it best to stay slightly inside the line, as one can always expand the cut later. With the outline established, a plunge router is used to remove most of the wood within the outline, starting by making plunge cuts around the boundary, and then cleaning up the remaining section. Care must be taken to stay away from the outline cut, in order to avoid ruining a straight final cut. The depth of the cut is set to allow at least 1/4" - 1/2" of the bow tie key projecting above the surface of the top. The real work begins now, using hand chisels to clean out the wood along the outline, gradually enlarging the routed section to be as closely matched as possible to the shape of the individual bow tie key. Having the knife-cut line in the surface aids in this effort, providing a seating for the point of the chisel blade. After the outline of the routed area is fit to the shape of the bow tie key, and all excess wood removed, a liberal layer of glue is applied to bottom & sides, and the bow tie piece slid into place. I normally set aside some sawdust from the wood top, mix it with glue, and work it into any small gaps in the seam between the two pieces. This prevents having open spaces on the finished product After allowing the glue to set overnight, it is time to remove the portion of the bow tie key that projects above the table top surface. I prefer using an angle grinder fitted with a Holey Galahad carbide grinding wheel from King Arthur Tools, as it makes quick work of the job. Care must be taken to avoid gouging into the surface of the top, but I personally find this easy to control. A belt sander can then be used to remove any areas still projecting above the surface, readying the table for the final sanding and finishing. This piece will eventually be used as the top for a small bench.
Here's another opportunity for rescuing something from the firewood pile. It is not uncommon for harvested trees to have sections where the center of the tree has rotted out over time, leaving a hollow center, even though the tree might appear to be healthy (the nutrients flow in the layers just below the bark, so a hollow core does not necessarily affect the health of the tree) These sections have no value in terms of the production of usable lumber, so they are trimmed from the saw logs before processing. But, when cut to length, and placed in a natural garden setting, they become perfect planters. This idea was first relayed to me by my brother, who operates the family lumber business, after having it suggested to him by a buyer from Terrain at Styer's. Hardwoods such as white oak, locust, black cherry, etc. are the best options, as these species will hold up better over time. Not that they will last forever, but in most situations, they should hold up well for several years. Obtaining and positioning the planters might be the easy part, as the selection and placement of plants is the crowning touch needed to create the finished product. These particular examples are displaying the incredible talent and vision of a master gardener.
My favorite creations have almost always started as pieces of wood or iron that have been relegated to the scrap heap, or firewood pile. A local lumber mill is a good source for interesting and unique pieces that have been removed from saw logs before being processed into usable material. Branches and weird growths are best trimmed from the logs before entering the mill. These scraps are then gathered for use as firewood Timber harvested from the forest will sometimes have hollow sections that have little or no production value, and will therefore be removed before entering the mill. Regular visits to the pile that results from this process has produced many pieces that will eventually end up as the foundation for a new creation. This firewood pile happens to be familiar to me, as it is located on my family's lumber mill, and has offered up many treasures over the years. It is also common to find discarded segments from areas where a large branch had broken away from the main trunk of the tree, as the growth patterns from these sections are unlikely to produce usable lumber. At the same time, these same growth patterns can produce highly figured graining, and a great start for the creative process. Last week, I came across one of these segments, cut from a red oak saw log. After slicing off only the section containing the figured graining, I will set it aside for air drying, and the chance to incorporate the piece into a future collection. Possibly similar to this existing lamp, which started as a piece cut from a similar section of a black cherry saw log several years ago
|
Details
AuthorAs Tinkerer-in-Chief, I enjoy getting lost in the process of creating unique works of art from materials that would otherwise be considered to be of little or no value. Hopefully these pages will allow some visibility into this world Archives
December 2017
Categories |