Cutting – Processes – Plural cutting steps
Reexamination Certificate
2001-09-24
2004-02-10
Shoap, Allan N. (Department: 3724)
Cutting
Processes
Plural cutting steps
C083S875000, C083S887000, C144S347000, C144S028720, C144S028600
Reexamination Certificate
active
06688197
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to machines for cutting wood, and in particular to machines for cutting dove-tail notches in pieces of lumber.
One type of dove-tail notch that has been used in the past for the construction of log cabins and other log buildings is the Finnish or Scandinavian dove-tail notch. This type of notch has a compound angle that provides at least two advantages over conventional dove-tail notches. First, the compound angle helps drain rain water out of the dove-tail joint because the surfaces of the dove-tail cut all have an angular component that faces outwardly and away from the joint. As the rain water flows downwardly, this angular component helps drain the water to the outside of the joint. Second, the compound angle of the Finnish or Scandinavian dove-tail notch helps make the dove-tail joint tighter as the lumber shrinks. For at least these two reasons, this type of dove-tail notch provides a desirable manner for securing lumber together, particularly lumber being used in a manner that exposes it to rain or other sources of water.
Scandinavian or Finnish dove-tail notches, however, are difficult to cut because of their compound angle. Cutting the compound angle has often been a labor-intensive project in the past that has led to a decline in the use of these types of joints. It would therefore be desirable to provide a manner of cutting these types of joints that reduced the labor and expense of the previous methods.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an apparatus for cutting dove-tail notches, such as Scandinavian or Finnish notches, that is simple to use and that allows these notches to be cut with a minimal amount of labor.
According to one embodiment of the invention, a lumber cutting assembly is provided that includes a longitudinally extending, generally horizontal support for supporting a piece of lumber to be cut. The cutting assembly further includes a first, second, and third saw. The first saw is positioned on a first side of the support while the second saw is positioned on an opposite side of the support. The first and second saw are movable toward and away from the support. The third saw is positioned adjacent a front end of the support and is movable longitudinally toward and away from the support.
According to another embodiment of the invention, an apparatus for cutting dove-tail notches in a piece of lumber is provided. The apparatus includes a trailer adapted to be towed by a truck or car and a lumber support positioned on the trailer. The apparatus further includes at least one saw for cutting at least one back cut in the lumber, as well as at least one saw for cutting at least one head cut in the lumber. The back cut is cut generally perpendicular to a top surface of the lumber and shortens the length of one of the sides of the lumber. The head cut defines a plane that is not perpendicular to the plane defined by the back cut and that is not perpendicular to the plane defined by the top surface of the piece of lumber.
According to another embodiment of the invention, an apparatus for cutting dove-tail notches is provided. The apparatus includes at least one band saw for cutting at least one back cut in the lumber, and at least one band saw for cutting at least one head cut in the lumber. The back cut shortens the length of one of the sides of the piece of lumber and is cut generally perpendicular to the top surface of the lumber. The head cut defines a plane that is not perpendicular to the plane defined by the back cut and that is not perpendicular to the plane defined by the top surface of the lumber.
According to still another aspect of the present invention, a method is provided for cutting a piece of lumber having a top surface and two side surfaces. The lumber is placed on a stationary support and a back cut is cut into each of the side surfaces. Two head cuts are also made in the lumber with each head cut defining a plane that is not perpendicular to the plane defined by the top surface nor the plane defined by one of the back cuts. The back cuts and the head cuts are made without ever rotating the lumber.
According to still other aspects of the present invention, the saw or saws for cutting the back cuts may be mounted on a movable platform that allows the saws to move toward and away from the lumber. The head saw may be pivotable between opposite sides of the lumber, and may further be mounted on a cart that allows the head saw to move toward and away from one end of the piece of lumber. The head saw may further be pivotable about a single horizontal axis, or about two horizontal axes that are perpendicular to each other. In still other aspects of the present invention, the saws may be powered by an electrical generator mounted on the trailer to facilitate the use of the apparatus in virtually any location and environment.
The dove-tail notch cutting machine of the present invention not only provides a simple and quick way of cutting dove-tail notches, but further facilitates the cutting of such notches by being portable. The apparatus can therefore be easily transported to a building site or other location where dove-tail notches are needed. The cutting machine of the present invention also generates dove-tail notches that are accurately cut and that can be easily replicated from one piece of lumber to the next. These and other benefits of the present invention will become apparent to one skilled in the art from the following specification when read in conjunction with the accompanying drawings.
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Nguyen Phong
Shoap Allan N.
Van Dyke Gardner, Linn & Burkhart, LLP
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