Geometrical instruments – Straightedge type – Plural straightedges – relatively moveable
Reexamination Certificate
2002-08-16
2004-02-24
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Straightedge type
Plural straightedges, relatively moveable
C033S417000, C033S423000, C033S425000, C033S471000, C033S023010
Reexamination Certificate
active
06694633
ABSTRACT:
BACKGROUND OF THE INVENTION
a. Field of the Invention
The present invention is related generally to the field of devices and tools useful in marking roof rafters for cutting to shape for installation.
More particularly the present invention is related to devices and tools useful in marking roof rafters for cutting to shape for installation that provide for the marking of the common cuts to be made in a roof rafter, the common ridge cut, the bird's mouth or seat cut, and the tail end cut.
Yet more particularly, the present invention is related to devices and tools that provide for marking of the physical relationship between the tail cut and the seat cut and, therefore, do not require a separate measurement be taken before marking of the seat cut.
Yet more particularly, the present invention is related to devices and tools that provide for ease of use in that multiple manual adjustments do not have to be made by the user in order to maintain the angular relationship of the rafter ridge cut and the seat cut.
In a yet further and final point of particularity, the present invention is related to devices and tools that are specifically designed for use in laying out the common cuts to be marked and made for a common roof rafter so that their manner of use is specifically and clearly indicated.
b. Description of the Prior Art
The common roof rafter is cut at its uppermost end at an angle so that the roof rafter, when installed, will provide the proper pitch to the roof while making a flush joinder to the roof ridge. This uppermost end cut is called the common ridge cut. At the lowermost end the common roof rafter is cut at an angle parallel to that of the common ridge cut so that the lowermost or tail end of the common roof rafter will be perpendicular to the ground, which is presumed to be level, and parallel to the vertical walls of the structure being roofed. At some point between the common ridge cut and the tail end cut the common roof rafter will cross over or lie upon the frame of the vertical wall of the structure being roofed. It is desirable that a cut be made in the common roof rafter such that the common roof rafter will provide a parallel surface to set upon the top of the vertical wall's frame. This cut is often called a bird's mouth cut or seat cut and permits the maximum load bearing surface from the common roof rafter to sit upon the top of the vertical wall's frame. Thus the three cuts that need to be made in a length of material to form a common roof rafter are the common ridge cut, the seat cut, and the tail cut.
Several devices and tools have been developed to assist the craftsman in the task of repetitively marking with appropriate angles and lengths for cutting lengths of material to be used as roof rafters. Such devices and tools include those disclosed by the following described U.S. Patents.
U.S. Pat. No. 15,600 discloses an instrument for laying out rafters which may be used for marking the common ridge cut and the tail cut, but doesn't make provision for the marking of the seat cut.
U.S. Pat. No. 2,212,331 discloses a carpenter's roof lay-out gauge which requires for its use the manual parallel alignment of a cross bar and the straight edge of a plate (page 2, lines 21-25) in order to mark the seat cut.
U.S. Pat. No. 4,712,307 discloses a rafter angle measuring device which incorporates a level into one arm, but does not make provision for measuring or marking of the seat cut.
U.S. Pat. No. 4,761,890 discloses an adjustable carpenters measuring tool which combines the functions of a square, a level, and a bevel tool into a single device. The single device does not provide for marking of the physical relationship between the tail cut and the seat cut, and thus requires a separate measurement be taken.
U.S. Pat. No. 5,384,967 discloses a collapsible rafter square which is adapted for the marking of plumb and level lines on roof rafters. The collapsible rafter square does not provide for marking of the physical relationship between the tail cut and the seat cut, and thus requires a separate measurement be taken.
U.S. Pat. No. 5,419,053 discloses a measuring tool which, by overlay of two protractor elements, permits calculation and marking of common rafter cut angles. The measuring device does not provide for marking of the physical relationship between the tail cut and the seat cut, and thus requires a separate measurement be taken.
U.S. Pat. No. 5,440,818 discloses a measuring device which, by cooperation of two protractor elements, permits the layout and marking of roof rafters. The measuring device does not provide for marking of the physical relationship between the tail cut and the seat cut, and thus requires a separate measurement be taken.
U.S. Pat. No. 6,293,028 discloses a construction tool which is useful for the marking of locations for the roof ridge cut, seat cut, and tail cut; however, no provision is made for setting the angle of such cuts.
Accordingly, it can be seen that the prior art provides less than ideal solutions for the problem commonly encountered by carpenters and craftsmen in laying out and marking common roof rafters for the roof ridge cut, seat cut, and tail cuts.
A first problem encountered in the prior art is that some prior art devices do not provide for the marking of the seat cut.
A further problem encountered in the prior art is that some prior art devices do not provide for marking of the physical relationship between the tail cut and the seat cut and, therefore, require a separate measurement be taken.
A yet further problem encountered in the prior art is that some prior art devices do not provide for ease of use in that multiple manual adjustments have to be made by the user in order to maintain the angular relationship of the rafter ridge cut and the seat cut.
A yet further and final problem encountered in the prior art is that some prior art devices by their design for general applicability to uses in the construction trades do not specifically and clearly indicate their use in laying out the common cuts to be marked and made for a common roof rafter.
SUMMARY OF THE INVENTION
The instant invention is of a common rafter and hip layout tool, useful in marking the common cuts to be made in a roof rafter. The common cuts to be made in a roof rafter are, at the uppermost end of the roof rafter, the common ridge cut; at the lowermost end of the roof rafter, the tail end cut, and at the point between the common ridge cut and the tail end cut where the common roof rafter will cross over or lie upon the frame of the vertical wall of the structure being roofed, the bird's mouth cut or seat cut.
Accordingly, it is an object of this invention to provide a device which is useful in marking roof rafters for cutting to shape for installation.
It is a further object of this invention to provide a device which is useful in marking roof rafters for cutting to shape for installation that provides for the marking of the common cuts to be made in a roof rafter, the common ridge cut, the bird's mouth or seat cut, and the tail end cut.
It is a yet further object of this invention to provide a device which provides for marking of the physical relationship between the tail cut and the seat cut and, therefore, do not require a separate measurement be taken before marking of the seat cut.
It is a yet further object of this invention to provide a device which provides for ease of use in that multiple manual adjustments do not have to be made by the user in order to maintain the angular relationship of the rafter ridge cut and the seat cut.
It is a yet further and final object of this invention to provide a device which is specifically designed for use in laying out the common cuts to be marked and made for a common roof rafter so that its manner of use is specifically and clearly indicated.
Description of Numeric References
1
. Common Rafter and Hip Layout Tool of the instant invention
10
. Main Body of the Common Rafter and Hip Layout Tool
11
. Slot in Main Body of the Common Rafter and Hip Layout Tool
12
Guadalupe Yaritza
Gutierrez Diego
LandOfFree
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