Scribe/guide tool adapted for stair construction

Details Scribe/guide tool adapted for stair construction Scribe/guide tool adapted for stair construction

1999-06-16

2001-05-22

Gutierrez, Diego (Department: 2859)

Geometrical instruments

Scriber

Curved line

C033S027030, C033S041100, C033S029000, C033S474000, C033S484000

Reexamination Certificate

active

06233835

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to construction tools, and more particularly is a scribe/guide tool used as a compass or for the layout of stair stringers.
BACKGROUND OF THE INVENTION
In construction, it is often necessary to perform measuring operations that require tools that serve as a compass. One such task is squaring floors and walls. Typically, the builder will use a pencil in conjunction with his tape or a string line to make these measurements. The width of the tape makes it very difficult to achieve an accurate measurement using the tape as a compass. Using the string line provides a more accurate measurement, but is very time consuming.
Another very time-consuming task in construction is laying out a stair stringer (or carriage) for a set of stairs. Every set of stairs is defined by the rise and run in which it will be installed. The rise is the vertical distance that the stairs will cover, and the run is the horizontal length occupied by the stairs. The first hurdle that must be overcome is determining the respective lengths for the risers and treads of the stairs. Defined in terms of each other, the length of the riser is the vertical distance between the individual treads, and the length of the tread is the horizontal distance between the individual risers. To determine these lengths, the builder considers local building codes in conjunction with the end user's desires, and is then able to calculate the proper lengths of risers and treads.
When the calculation problem has been solved, the next step is to physically lay out the stair stringer on the lumber workpiece. This task is made somewhat difficult because of the necessity of repeated orthogonal measurements that must be made to mark the correct boundaries of the risers and the treads. The current art method requires the builder to use a triangulation method in which one leg of a right triangle (defined by a framing square) is the riser, the second leg of the triangle is the tread, and the hypotenuse is situated at the edge of the workpiece.
After marking the position of the riser and the tread, the builder needs to mark on the edge of the workpiece the end point of one step to start the layout of the next step. This leads to a source of error due to the fact that the edge of the workpiece can never be completely square. The mill run construction grade lumber typically used for stringers has a significant radius of curvature. This radius means that the hypotenuse of the triangle used to lay out the steps, instead of being on the surface of the board, is in actuality located in open space. The builder will therefore mark the end point of the step by sighting along a line that is perpendicular to the square, and that passes through the end of the hypotenuse. Because the builder has to make this sight at nearly an arm's length, the marking and repositioning of the framing square is subject to significant accumulated error. Moreover, the builder may grow weary of continually repositioning himself to have a the best available sight line to the end of the square.
Accordingly, it is an object of the present invention to provide a tool that functions as an accurate compass.
It is another object of the present invention to provide a method to reduce the accumulated error created by the repeated positioning of a framing square in stair stringer layouts.
It is a further object of the present invention to provide a tool that allows the user to reduce the amount of time required to mark out a stringer.
It is a still further object of the present invention to provide a tool that can be used for other marking operations as weli, specifically operations that ordinarily require a compass.
SUMMARY OF THE INVENTION
The present invention is a scribe/guide tool that is used as a scribe tool in conjunction with a straightedge or a rule to function as a compass to aid in the layout of stair stringers. The tool is most often used in pairs. A scribe means is removably inserted into the body of the tool.
The tool comprises a clamping means with smooth surfaces to affix the scribe/guide tool to another measuring tool. In the preferred embodiment, the scribe/guide tool comprises a main body with a clamp element secured therein. The clamp element is moved up and down relative to the main body via a screw drive. The scribe means is secured in the screw drive by a retaining ring. The position indicating edges of the main body of the tool are tapered to a very narrow point to reduce the possibility of accumulated error when marking a workpiece with the tool as a guide.
An advantage of the present invention is that it may be used to accurately mark repeated equally spaced distances on a workpiece.
Another advantage of the present invention is that it reduces the possibility of accumulated error when marking a rounded edge of a workpiece.
A still further advantage of the present invention is that it greatly simplifies the layout procedure for stair stringers.
These and other objects and advantages of the present invention will become apparent to those skilled in the art in view of the description of the best presently known mode of carrying out the invention as described herein and as illustrated in the drawings.


REFERENCES:
patent: 175113 (1876-03-01), Kuhns
patent: 939597 (1909-11-01), Hurst
patent: 2621409 (1952-12-01), Dvorak
patent: 2621412 (1952-12-01), Slusher, Jr.
patent: 2805484 (1957-09-01), D'Aoust
patent: 3025602 (1962-03-01), Iovinelli
patent: 3623232 (1971-11-01), Mahlstadt
patent: 4393600 (1983-07-01), Coe

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