Geometrical instruments – Straightedge type – Plural straightedges – relatively moveable
Reexamination Certificate
2003-01-07
2004-12-14
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Straightedge type
Plural straightedges, relatively moveable
C033S0010AP
Reexamination Certificate
active
06829837
ABSTRACT:
BACKGROUND AND TECHNICAL FIELD OF THE INVENTION
The present invention is directed towards a tool for use with construction projects. Although the invention may be used in many fields, such as plumbing, roofing, and drafting, it has particular relevance to the field of finish carpentry and will be discussed with respect thereto.
Carpenters must frequently join materials at an angle in a manner commonly known as a miter joint. A miter joint typically consists of two pieces of material that are joined at a corner, where each of the pieces is cut at a bisecting angle of the corner angle requiring the miter joint. Miter joints are used on molding surrounding doors, windows, and floor bases as well as in the risers and runs on staircase stringers. As doors, windows, walls, and staircases are frequently not perfectly square due to natural imperfections, the actual angle required for the miter joint must first be determined and then the materials cut to this angle.
Devices are known for measuring the required miter angle of a particular joint. These measuring devices typically consist of two members or legs that are joined at a pivot point. The measuring device is positioned within a corner requiring a miter joint and the members of the device are then pivoted such that they contact the surfaces of the corner that create the angle. A scale is provided on the device that, when the members are pivoted to the correct angle, enable the user to read the required miter angle for the corner. See, for example, U.S. Pat. No. 6,237,238 B1 issued to Shapiro. The required miter angle may then be set on the apparatus that will be used to cut the material to be joined. Alternatively, another device may be set to the required angle and used to scribe this angle onto the material to be joined. In this method the cutting apparatus is aligned to the mark on the material by sight.
However, problems exist with these methods with regards to translating the measured miter angle into a finish cut on the material to be joined. Imprecision between the gage scales of the device used for measuring the required miter angle and of the cutting apparatus can result in inaccurate miter cuts, resulting in miter joints that are not properly flush. Also, human imprecision is added when the operator must read one scale and transfer the value to another scale. Additionally, it is inefficient to set the angle on another device and use it to scribe the required angle onto the material to be joined.
The present invention overcomes such difficulties and enables the operator to accurately and efficiently determine a required miter angle for a given joint and directly transcribe that angle onto the material to be cut. By directly transcribing the angle onto the material to be cut, the cutting apparatus can be accurately adjusted by sight by aligning the cutting blade over the transcribed mark prior to cutting and any imprecision associated with the cutting apparatus' gage scale is avoided. Alternatively, the present invention can be used as a jig to set the cutting apparatus to the proper cutting position. Further, the tool is constructed such that miter angles for both internal corners and edge corners can be determined.
SUMMARY OF THE INVENTION
The present invention discloses a miter angle indicating tool which has an angle indicating blade, a bevel blade, and a case; all of which are pivotally attached to each other at their respective ends. The indicating blade is constructed with an indicating edge that aligns through the center point of the pivot point formed by the pivotal attachment of the indicating blade, the bevel blade, and the case.
In use, the tool is placed into or around a corner, and edges of the bevel blade and case are made to contact the surfaces comprising the corner. To obtain the miter or bisecting angle, the indicating blade is then positioned such that the indicating edge intersects a point established by the intersection of the interior edges of the bevel blade and case. When the tool is secured in this position, it can then be used to transcribe the miter angle onto a work surface or as a jig to set the cutting position of a cutting apparatus.
It is an object of this invention to provide an accurate indicator of the miter angle required for a work surface. It is a further object of this invention to avoid the inaccuracies and time delays associated with the reading of a gage scale on known miter angle measurement devices. It is still a further object of this invention to enable a miter angle to be transcribed onto a work surface or to provide a jig with which to set a miter angle cutting apparatus. These and other objects, features, and advantages of the invention will be made apparent from the following description and attached drawings.
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