Log staircase and a method of producing components for a log staircase

A log staircase is disclosed along with a method of producing components for the log staircase. The log staircase includes an elongated stringer capable of angularly extending from a lower level to an upper level. The stringer has an outer circumference with a notch formed therein. A protuberance extends upward from the notch. The log staircase also includes a tread having a semicircular periphery with a flat surface. An opening is formed in the semicircular periphery of the tread. The opening is designed to mate with the protuberance to retain the flat surface crossways to the stringer. The method includes cutting a number notches and protuberances in each of a pair of stringers, and cutting a pair of openings in a predetermined number of treads which are capable of mating with the protuberances to retain each of the treads crossways to the pair of stringers.

FIELD OF THE INVENTION

This invention relates to a log staircase and a method of producing components for a log staircase.

BACKGROUND OF THE INVENTION

The various components needed for installing a log staircase in a new log home or log building can be produced or fabricated at a manufacturer in a controlled environment. The manufacturer can produce the needed stringers, treads, etc. to specific dimensions such that the log staircase will have a particular length, height, angle of inclination, and a desired number of treads. The various components, including any needed fasteners, can then be bundled and shipped to the building site where the log staircase is to be installed. The installation of the log staircase into the new log home or log building can occur at an appropriate time in the construction cycle. This process has been successfully used in building log homes, many of which are located in remote areas. In the case of manufacturing internal and external log staircases, multiple C-shaped notches are formed in each of a pair of support stringers. Each of the C-shaped notches extends through more than half of the diameter of each stringer. Each tread or step is shaped to have a semicircular periphery with a flat surface. The flat surface forms the step portion of each tread. The semicircular periphery of each tread is designed to be positioned within one of the multiple C-shaped notches formed in each of the pair of stringers. During installation, the pair of stringers is secured in place between a lower level and an upper level. The semicircular periphery of each tread is then positioned in a pair of the C-shaped notches so as to bridge across the pair of stringers. Each tread is then shimmed and adjusted to obtain a horizontal alignment from left to right and from front to back. Once a tread is properly aligned, it is then secured in place by appropriate hardware, such as lag screws or bolts.

As is evident from the above description, the installation of such a log staircase normally requires two skilled laborers who have some previous experience with installing such log staircases. With each log staircase, it is very important that each tread or step be attached between the pair of stringers such that it lies in a horizontal plane from left to right and from front to back. Since the size and location of each C-shaped notch can vary depending upon the diameter of each stringer and because the semicircular periphery of each tread can also vary, it becomes necessary to shim and adjust each tread to obtain proper alignment. Each tread is then fastened in place to prevent movement, wobble, rotation or rocking. If the treads are not properly aligned, they can create a safety hazard to a person walking up or down the log staircase. Furthermore, if each tread is not horizontally aligned and evenly spaced from an adjacent tread, the log staircase will not pass building code.

Now, a log staircase and a method of producing components for a log staircase have been invented that allow a log staircase to be installed at a building site more quickly and efficiently, and in a manner that will satisfy building code. In addition, the log staircase can be installed by two persons that may not be skilled laborers in this task.

SUMMARY OF THE INVENTION

Briefly, this invention relates to an interior or an exterior log staircase. The log staircase includes an elongated stringer capable of angularly extending from a lower level to an upper level. The stringer has an outer circumference with one or more notches formed therein which do not extend through more than half of the diameter of the stringer. A protuberance extends upward from each of the notches. The log staircase also includes one or more treads each having a semicircular periphery with a flat surface. An opening is formed in the semicircular periphery and is aligned at an acute angle to the flat surface. The opening is capable of mating with one of the protuberances formed in the stringer to retain the flat surface of the tread crossways to the stringer.

In another embodiment, the log staircase includes a pair of elongated, spaced apart stringers. One stringer is aligned parallel to the other stringer and each stringer is capable of angularly extending from a lower level to an upper level. Each of the pair of stringers has an outer circumference with a number of notches formed therein. The notches do not extend through more than half of the diameter of each stringer. Each of the notches formed in one stringer is aligned horizontally along a common axis with one of the multiple notches formed in the other stringer. In addition, each of the notches has a protuberance extending upward therefrom. The log staircase also includes a number of treads each having a semicircular periphery with a flat surface. Each of the treads has a pair of spaced apart openings formed in the semicircular periphery with each of the openings being aligned at an acute angle to the flat surface. Each of the pair of openings is capable of mating with one of the protuberances formed in each of the stringers to retain each of the flat surfaces of the tread crossways to the pair of stringers.

The method of producing components for a log staircase includes selecting a pair of elongated, dried natural logs free of bark as stringers. Each of the pair of stringers has a length and an outer circumference with a relatively constant diameter extending along the length thereof. The outer circumference of one of the pair of stringers is similar in size to the outer circumference of the other stringer. The method also includes cutting a number of notches into the outer circumference of each of the pair of stringers. The notches do not extend through more than half of the diameter of each stringer. Each of the notches is longitudinally aligned with one another and each has a protuberance extending upward therefrom. Each of the notches formed in one of the pair of stringers is aligned horizontally along a common axis with one of the notches formed in the other stringer. The method further includes forming a predetermined number of treads equal to the number of notches formed in each of the pair of stringers. Each of the treads has a semicircular periphery with a flat surface. A pair of spaced apart openings is cut into the semicircular periphery of each of the treads and each is aligned at an acute angle to the flat surface. Each of the pair of openings is capable of mating with one of the protuberances formed in each of the pair of stringers. Lastly, the method includes gathering or bundling together the pair of stringers and the predetermined number of treads for shipment to a customer.

The general object of this invention is to provide a log staircase for connecting separate levels. A more specific object of this invention is to provide a method of producing components for a log staircase.

Another object of this invention is to provide an interior or an exterior log staircase which can be easily assembled at a building site.

A further object of this invention is to provide a log staircase for a log home or log building which requires less time to assemble at a building site.

Still another object of this invention is to provide a log staircase which allows each tread to be horizontally secured from left to right and from front to back to a pair of stringers.

Still further, an object of this invention is to provide a log staircase which utilizes a pair of openings formed in each of the treads wherein each opening is designed to mate with a protuberance formed in each of the pair of stringers to provide a secure attachment therebetween.

Other objects and advantages of the present invention will become more apparent to those skilled in the art in view of the following description and the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1, a prior art log staircase10is shown which includes a pair of spaced apart log stringers12each having an outer diameter of approximately the same diameter. Each log stringer12has multiple C-shaped notches14cut therein. Each C-shaped notch14removes more than 50% of the material forming the outer diameter at that particular location. A number of wooden treads16, equal to the number of multiple C-shaped notches14formed in each log stringer12, are horizontally positioned across the pair of log stringers12. Each of the wooden treads16has a semicircular periphery18with a flat upper surface20. The semicircular periphery18of each wooden tread16is positioned in a pair of the C-shaped notches14and is secured in place by appropriate hardware (not shown), such as lag screw, bolts, etc. One drawback with this design is that the semicircular periphery18of each wooden tread16is not perfectly round and therefore is able to move, wobble, rotate and/or rock within the pair of C-shaped notches. Because of this, shims must be inserted and adjustment need to be made to ensure that each wooden tread16lies in a horizontal plane within a pair of the C-shaped notches14. Each wooden tread16must be horizontally aligned from left to right and from front to back. Furthermore, each wooden tread16must be at a set vertical distance from an adjacent wooden tread16in order to satisfy existing building code. Once the wooden treads16are properly adjusted, appropriate hardware is used to secure each of the wooden treads16to the pair of stringers12.

Referring toFIG. 2, a log staircase22is shown which can be either an interior log staircase or an exterior log staircase. By “interior log staircase” it is meant a log staircase that is installed within a home, building or other structure. By “exterior log staircase” it is meant a log staircase that is installed on the outside of a home, building or other structure. An exterior log staircase is usually exposed to the elements. The log staircase22includes at least one stringer24and one or more treads26secured to the stringer24. InFIG. 2, a pair of spaced apart elongated stringers24, each having approximately the same diameter, is depicted having thirteen treads26secured across the pair of stringers24. The pair of stringers24is aligned parallel to one another and they can be spaced apart by any desired distance. A distance of from about 1 foot to about 5 feet is common. The pair of stringers24is typically installed at an angle ranging anywhere from between about 20 degrees to about 55 degrees. The pair of stringers24angularly extends between a lower level28and an upper level30. For example, the lower level28can be a ground floor and the upper level30can be a second floor. Alternatively, the lower level28can be a basement, the ground floor, a first floor, a first landing, a second floor, etc. and the upper level30can be the first floor, a porch, a second floor, a second landing, an attic, etc. Wherever situated, the upper level30is located vertically above to the lower level28.

Each of the pair of stringers24is depicted as having an outer circumference and an overall cylindrical shape. By “outer circumference” it is meant a boundary line of a circle, figure, area or object. Each stringer24has a first end32and a second end34. Each of the stringers24has a longitudinal central axis X-X and a length l measured between the first and second ends,32and34respectively. The length l of a stringer24can vary depending upon the height, width and angle of inclination of the log staircase as well as the material from which each stringer24is formed.

As shown inFIG. 2, each stringer24is depicted as a full wooden natural log. The log can be from a hardwood tree or from a softwood tree. The log can come from various trees or shrubs, including but not limited to: conifers, white cedar, red cedar, Northern white pine, Norway or red pine, Southern yellow pine, lodge pole pine, jack pine, Douglas fir, hemlock, oak, maple, etc. By “conifer” it is meant any of various mostly needle-leaved or scale-leaved, chiefly evergreen, cone-bearing gymnospermous trees or shrubs, such as pines, spruces and firs. By “cedar” it is meant any of several Old World evergreen coniferous trees of the genus Cedrus, having stiff needles and large seed cones or any of several other evergreen coniferous trees or shrubs, such as the incense cedar or red cedar. In addition, each stringer24can be constructed of metal, iron, aluminum, a metal alloy, thermoplastics, composite materials, fiberglass, reinforced fiberglass, etc. or be formed from one or more materials that is covered or wrapped in a wood veneer or a material appearing to be wood. By “veneer” it is meant a thin surface layer, as of wood, glued to a base material or a decorative facing. Desirably, each stringer24is constructed from a full log that has had the bark removed. The log can be dried such as by air drying, kiln drying or by a combination of both air and kiln drying. The log can be left unfinished or it can be coated, stained or painted with a lacquer, shellac, a varnish or some other coating or paint. By “lacquer” it is meant any of various clear or colored synthetic coatings made by dissolving cellulose derivatives together with plastizers in volatile solvents and used to impart a high gloss to the surface. By “shellac” it is meant a thin varnish made by dissolving this substance in denatured alcohol, used to finish wood. By “varnish” it is meant a paint containing a solvent and an oxidizing or evaporating binder, used to coat a surface with a hard, glossy transparent film.

Optionally each stringer24can be a full wooden log that has been mechanically peeled to give it the appearance of having been hand peeled. In past years, logs were scraped with a hand tool, such as a draw knife, to remove the bark and/or to shape the diameter of the log. After the logs were peeled or scraped, they exhibited shave marks on the outer surface which are now considered to be aesthetically pleasing in appearance. In addition, most logs contain one or more cracks, checks, knots, etc. which will enhance the rustic appeal of the log but which do not compromise its structural integrity. Desirably, such cracks, checks, knots etc. should be left in their natural state and should not be covered up.

Still referring toFIG. 2, each stringer24has a diameter d which is relatively constant along its length l. The diameter d can range from between about 6 inches to about 13 inches. Desirably, the diameter d of each stringer24ranges from between about 8 inches to about 12 inches. More desirably, the diameter d of each stringer24ranges from between about 9 inches to about 11 inches. Most desirably, the diameter d of each stringer24is about 10 inches. Due to the removal of any bark and/or the mechanical peeling process mentioned above, the outer circumference of each stringer24will not be perfectly round and the diameter d will not be a constant from the first end32to the second end34. However, each stringer24will have a generally cylindrical shape of a relatively constant diameter d, plus or minus a couple of inches, from the first end32to the second end34. In addition, when two or more stringers24are utilized, each of the stringers24should have a diameter d and an outer circumference which are similar, although not identical, in size to the other stringers24.

Referring now toFIG. 3, a log staircase22′ is shown having a single stringer24having two treads26secure to it. Each of the treads26extend crossways or perpendicular to the longitudinal central axis X-X of the stringer24. In addition, the upper tread26is vertically spaced a set distance above the lower tread26.

Referring toFIG. 4, a log staircase22″ is shown having three spaced apart stringers24aligned parallel to one another. Two treads26are secure across the three stringer24in a crossways or perpendicular fashion relative to the longitudinal central axis X-X of each stringer24. Each of the three stringers24can be equally spaced apart from an adjacent stringer24or one of the stringers24can be aligned closer to one of the other stringers24, if desired. Similar to the embodiment shown inFIG. 3, the upper tread26is vertically spaced a set distance above the lower tread26.

Referring now toFIG. 5, a side view of the log staircase22is depicted. The log staircase22has a height h, a width w and an angle of inclination θ. The height h is measured as the vertical distance from the lower level28upon which the first end32of each stringer24rests to the upper level30which includes the height of the beams, supports, flooring, etc. used to construct the floor of the upper level30. The width w is measured as the horizontal distance between an outer edge of the first end32to an outer edge of the second end34. The angle of inclination θ is measured between the lower level28and the lower surface of each stringer24. The angle of inclination θ is depicted at approximately 38.5 degrees inFIG. 5. However, as mentioned above, the angle of inclination θ can vary to allow the log staircase22to fit within the dimensions provided by an architect. For safety reasons, the angle of inclination θ should not exceed 55 degrees. One will also notice that inFIG. 5, the elongated stringer24has a longitudinal central axis X-X and all of the thirteen treads26are secured to the stringer24such that they are all located on one side of the longitudinal central axis X-X. It should be understood that the number of treads26and the spacing between adjacent treads26can vary to suit one's particular requirements and the building codes of a particular jurisdiction. InFIG. 5, the log staircase22has a nominal spacing value n. The nominal spacing value n is the distance measured between the inward edge of a lower tread26and the lower edge of the adjacently located upper tread26at a point where the upper tread26intersects the outer circumference of the stringer24. The nominal spacing value n can vary to suit one's particular requirements. The nominal spacing value n can range from between about 3 inches and 5 inches. InFIG. 5, the nominal spacing value n is approximately 3.4 inches.

Phrased another way, each of the notches36formed in a stringer24should be spaced at least about 2 inches apart from an adjacent notch36when measured parallel to the longitudinal central axis X-X. Desirably, each of the notches36formed in a stringer24should be spaced at least about 2.25 inches apart from an adjacent notch36when measured parallel to the longitudinal central axis X-X. More desirably, each of the notches36formed in a stringer24should be spaced at least about 2.5 inches apart from an adjacent notch36when measured parallel to the longitudinal central axis X-X. When two or more stringers24are utilized, the notches36formed in each of the stringers24should be spaced at least about 2 inches apart from an adjacent notch36when measured parallel to the longitudinal central axis X-X.

Referring now toFIGS. 6-10, the elongated stringer24has a relatively constant diameter d and an outer circumference. The outer circumference can be approximately round, circular, oval, elliptical, have a racetrack configuration or have some other geometrical configuration. Typically, the outer circumference is irregular in shape and is not completely round or circular. This is especially true if the log has been subjected to a peeling process. The stringer24also has at least one notch36formed therein which does not extend more than 50% through the diameter of the stringer24. Desirably, the stringer24will have from between two to fifteen notches36. More desirably, the stringer24will have from between three and thirteen notches36. If the stringer24is used for an exterior staircase22, then it will usually have fewer notches36than if it was used to form an interior staircase22. One reason for this is that an exterior staircase22, such as from the ground to a porch will normally only have one to six steps while an interior staircase22spanning between a ground floor and the next upper floor will usually have eight to thirteen steps.

InFIG. 6, the stringer24is depicted as having four spaced apart notches36although additional notches36can be utilized if more steps are required. A notch36will be formed in each stringer24so as to correspond to the number of treads26required for a particular log staircase22,22′ or22″. Desirably, from one to fifteen notches36are formed in a staircase22,22′ or22″. More desirably, from two to thirteen notches36are formed in a staircase22,22′ or22″. However, in some staircases22,22′ or22″ more than fifteen notches15can be utilized. When two or more notches36are present, each notch36will be equally spaced apart from an adjacent notch36. The presence of multiple notches36can give each stringer24a scallop appearance. By “scallop” it is meant one of a series of curved indentations formed along at least a portion of the length of a member.

One can initially vary the size, configuration and height h1of the notches36one wishes to cut or machine into each stringer24. However, when a pair of stringers24is utilized to form a log staircase22, it should be understood that all of the notches36present in the pair of stringers24must be identical in size, configuration and height h1. As depicted inFIG. 10, each of the notches36has a height h1that should be less than half of the diameter d of the stringer24in which it is formed. Desirably, each notch36is formed with a height h1that is less than 30% of the thickness of the stringer24. More desirably, each notch36is formed with a height h1that is less than 25% of the thickness of the stringer24. By forming each notch36to be less than half of the thickness of each stringer24, one can obtain a stronger log staircase22and reduce the likelihood that the stringers24will flex during use of the log staircase22. Desirably, each notch36has a height h1of less than about 3.5 inches. More desirably, each notch36has a height h1ranging from between about 1.5 inches to about 3.5 inches. Even more desirably, each notch36has a height h1ranging from between about 2 inches to about 3 inches. Most desirably, each notch36has a height h1of about 2.5 inches.

It should be understood that when two or more log stringers24are utilized, each log stringer24is aligned parallel to one another and each has at least two, and desirably, multiple notches36formed therein as is shown inFIGS. 2 and 4. The multiple notches36formed in one log stringer24are horizontally aligned with the multiple notches36formed in the other stringer(s)24. Desirably, each notch36formed in one of the log stringers24will be horizontally aligned along a common axis with a notch36formed in the other log stringer24.

As best shown inFIGS. 7-10, the notch36is uniquely formed. InFIG. 8, the notch36has a length l1and a width w1. The length l1is measured parallel to the longitudinal central axis X-X while the width w1is measured perpendicular to the longitudinal central axis X-X. The length l1of the notch36is longer than the width w1. However, the length l1of the notch36could be less than or equal to the width w1depending upon the configuration of the notch36. InFIGS. 7 and 8, the notch36is depicted as having a partial oval configuration when viewed from the top. The notch36can be described as a concave cavity38having a squared off end40and a lower surface42. The lower surface42is rough in finish so that it can better grip a mating tread and prevent slippage therebetween. Desirably, the lower surface42contains small ridges, serration or corrugations to enhance its ability to grip and retain a mating tread. The concave cavity38is best depicted inFIG. 10when one views a notch36from the side.

Still referring toFIGS. 7 and 8, a protuberance44is positioned within the dimensions of the notch36. By “protuberance” it is meant something, such as a bulge, knob or swelling that protrudes upward or outward. Each protuberance44has a length l2and a width w2. The length l2and the width w2of each protuberance44is less than the length l1and the width w1, respectively, of the notch36. Each protuberance44can have any desired geometrical shape. InFIG. 8, the protuberance44is depicted as having a partial oval configuration when viewed from the top. The protuberance44extends upward from the lower surface42of the concave cavity38, seeFIG. 9. The protuberance44has a convex shape extending across its width w2. As depicted inFIG. 8, the length l2of the protuberance44is of a greater dimension than the width w2. However, as will be understood by those skilled in the art, the length l2of the protuberance44could be less than or equal to its width w2, if desired, depending upon the overall configuration of the protuberance44. The length l2of the protuberance44is aligned parallel to the longitudinal central axis X-X of the stringer24in which it is cut or formed.

Referring toFIGS. 9 and 10, the protuberance44has an apex46which is located along a line that lies within the confines of the outer circumference of the stringer24. Desirably, the apex46of the protuberance44is aligned approximately parallel to the longitudinal central axis X-X of the stringer24. More desirably, the apex46of the protuberance44is aligned parallel to the longitudinal central axis X-X of the stringer24, seeFIG. 10. The apex46of the protuberance44can be aligned flush with or be located within the confines of the outer circumference of the stringer24. InFIG. 9, one can see that the apex46is located a distance d1within the confines of the outer circumference of the stringer24. Desirably, the apex46is located a distance d1of from between about 0.1 inches to about 2 inches within the confines of the outer circumference of the stringer24. Desirably, the apex46is located a distance d1of from between about 0.75 inches to about 1.5 inches within the confines of the outer circumference of the stringer24. More desirably, the apex46is located a distance d1of at least about 1 inch within the confines of the outer circumference of the stringer24. The distance d1is measured perpendicular to a point which would be located on the outer circumference if the notch36was not present.

It should be understood that even though the apex46of the protuberance44has been explained above as being a line, it could also be a point.

Referring toFIG. 10, the notch36has a height h1which is measured from the bottom of the lower surface42to the outer circumference. This height h1can vary in dimension. Generally, for a stringer24having a diameter d of 13 inches or less, the height haof the notch36will range from between about 1.5 inches to about 3.5 inches. Desirably, the height h1of the notch36will range from between about 2 inches to about 3 inches. More desirably, the height h1of the notch36will be about 2.5 inches. The notch36can also be formed with a radius r. The notch36can have a radius r which ranges from between about 5 inches to about 9 inches. Desirably, the notch36can have a radius r which ranges from between about 6 inches to about 8 inches. More desirably, the notch36can have a radius r which ranges from between about 6.5 inches to about 7.5 inches.

It should be noted that the above described notch36and protuberance44design is now being referred to by the manufacturer who employs the inventors as a “DUAL COPE LOG STAIRWAY”. DUAL COPE LOG STAIRWAY is a State of Wisconsin registered trademark owned by The Armstrong Creek Company having an office at 612 C Avenue, Goodman, Wis. 54125.

Referring now toFIG. 11, a tread48is shown which is designed to be secured to two spaced apart stringers24which are aligned parallel to one another. The tread48can be half of a full wooden natural log cut lengthwise. The tread48is identical to the tread26shown inFIG. 2. The tread48can be formed from a log which is of the same species as the logs used for the stringers24or it can be of a different species. Desirably, the treads48and the stringers24are from the same tree species. The tread48has a half round appearance with a semicircular periphery50and a flat surface52. The semicircular periphery50may not be constant over its entire length. The tread48has a longitudinal central axis X1-X1. As with the stringers24, each tread48should have any bark removed and can be processed to have a peeled appearance. Each tread48has a diameter d2which will correspond to the width of the flat surface52. The diameter d2or the width of the flat surface52is aligned perpendicular to the longitudinal central axis X1-X1. The diameter d2of each tread48can range from between about 7 inches to about 14 inches. Desirably, the diameter d2of each tread48can range from between about 9 inches to about 13 inches. More desirably, the diameter d2of each tread48can range from between about 10 inches to about 12.5 inches. Even more desirably, the diameter d2of each tread48can range from between about 11 inches to about 12 inches. Typically, in designing a log staircase22to be both functional and aesthetically pleasing, the diameter d2or width of each tread48should be larger in dimension than the diameter d of each stringer24. Desirably, each of the pair of stringers24has a diameter d of at least 6 inches and the flat surface52of each tread48has a width that is at least 1 inch greater than the diameter d of each of the pair of stringers24.

Multiple treads26or48can be used to construct a staircase22,22′ or22″. The number of treads26or48will vary depending upon the height h of the staircase22,22′ or22″ and the vertical spacing between each of the treads26or48. Typically, the number of treads26or48used in a staircase22,22′ or22″ can range from 1 to 25 treads26or48. Desirably, from one to fifteen treads26or48are present in each staircase22,22′ or22″. More desirably, from two to thirteen treads26or48are present in each staircase22,22′ or22″.

InFIG. 11, each tread48has a length l3which can vary for each log staircase. In the log staircase22shown inFIG. 2wherein a pair of stringers24is present, each tread26can have a length l3which can range from between about 2 feet to about 6 feet. Desirably, when the log staircase22utilizes a pair of stringers24, each tread26has a length l3of between about 3 feet to about 5 feet. In a log staircase22′, such as that shown inFIG. 3having a single stringer24, each tread26can have a length l3which can range from between about 1 foot to about 3 feet. Desirably, when the log staircase22′ utilizes a single stringer24, each tread26has a length l3of between about 1.5 feet to about 2.5 feet. In a log staircase22″, such as that shown inFIG. 4having three stringers24, each tread26can have a length l3which can range from between about 6 feet to about 14 feet. Desirably, when the log staircase22″ utilizes three stringers24, each tread26has a length l3of between about 8 feet to about 12 feet.

Referring toFIG. 2, the flat surface52of each tread26forms the upper portion of each step when assembled into the log staircase22,22′ or22″. The semicircular periphery50of each tread26will form the lower or underneath portion of each step of the assembled log staircase22,22′ or22″.

Returning toFIG. 11, one or more openings54are formed in the semicircular periphery50. The number of openings54will correspond to the number of stringers24the log staircase22,22′ or22″ will utilize. For example, inFIG. 3, one opening54is formed in each tread26; inFIG. 4, three openings54are formed in each tread26; and inFIG. 2, two openings54are formed in each tread26. The openings54can vary in configuration. InFIG. 11each of the openings54has the appearance of a concave pocket. The openings54are aligned at an acute angle to the flat surface52. By an “acute angle” it is meant an angle of less than 90 degrees. InFIG. 11, two openings54are depicted, each spaced apart by the same distance that the pair of stringers24will be spaced apart. Each of the openings54is aligned perpendicular to the longitudinal central axis X1-X1. Each opening54is sized, shaped and configured to mate with one of the protuberances44formed in each notch36cut into the pair of stringers24. By “mate” it is meant to join closely. Desirably, each opening54can be machined or cut so as to be slightly larger in size, from between about 0.25 inches to about 0.0375 inches larger, than the protuberance44it will mate with. This small size difference provides for final adjustment of each tread48relative to the pair of stringers24. When each of the openings54mates with one of the protuberances44formed in each of the pair of stringers24, the tread48will be secured across the pair of stringers24such that the flat surface52of each tread48extends horizontally crossways relative to the pair of stringers24. By “crossways” it is meant to be or lie in a cross direction; across. Each tread48also has a first end56and a second end58. When each of the treads48is securely affixed across the pair of stringers24, the first and second ends,56and58respectively, will extend horizontally outward beyond the diameters d of each of the pair of stringers24. The distance that each of the first and second ends,56and58respectively, can extend outward beyond the diameter d of each of the pair of stringers24can vary but normally will range from between about 6 inches to about 2 feet, seeFIG. 2.

Referring now toFIGS. 12-15, the left half of the tread48is shown to better depict the configuration of one of the openings54. As mentioned above, the opening54is configured as a concave pocket although other configurations can be used. InFIG. 14, the opening54has a width w3measured parallel to the longitudinal central axis X1-X1. The width w3can range from between about 4 inches to about 8 inches. Desirably, each opening54has a width w3which can range from between about 5 inches to about 7 inches. More desirably, each opening54has a width w3which can range from between about 5.5 inches to about 6.5 inches.

Still referring toFIG. 14, each opening54is at least partially surrounded by an enlarged pocket60. The enlarged pocket60can have any desired geometrical configuration. InFIG. 14, the enlarged pocket60is depicted as having at least a partial oval shaped perimeter. The enlarged pocket60extends outward from a portion of the openings54. Desirably, each enlarged pocket60extends outward in multiple directions from the periphery of at least a portion of the opening54. Each of the enlarged pockets60has a width w4which is at least about 1 inch larger than the width w3of the opening54. Desirably, each of the enlarged pockets60has a width w4which is at least about 2 inches larger than the width w3of the opening54. More desirably, each of the enlarged pockets60has a width w4which is at least about 2.5 inches larger than the width w3of the opening54.

Referring toFIG. 15, each enlarged pocket60can be formed with a radius r1. The enlarged pocket60can have a radius r1which ranges from between about 5 inches to about 9 inches. Desirably, the enlarged pocket60can have a radius r1which ranges from between about 6 inches to about 8 inches. More desirably, the enlarged pocket60can have a radius r1which ranges from between about 6.5 inches to about 7.5 inches. Each enlarged pocket60also has a height h2of less than about 1 inch. Desirably, each enlarged pocket60has a height h2of less than about 0.5 inches. The function of the enlarged pocket60is to mate with the concave cavity38of one of the notches36formed in each of the stringers24. By so mating, the tread48can be properly situated into one of the notches36and the protuberance44can be positioned within the opening54. During assembly of the treads48into the notches36formed in a pair of stringers24, builders caulk, an adhesive such as a construction adhesive, glue or some other kind of binding agent known to those skilled in the art, can be used to secure the two members36and48together.

The engagement between the protuberance44and the opening54is so precise that each tread48is horizontally positioned relative to a pair of stringers24. Each of the treads48will lie in a horizontal plane from left to right, from the first end56to the second end58, and from front to back. Many state building codes specify the range of tilt from front to back of each tread48that is permissible before a violation is cited. In some jurisdictions, the amount of tilt is limited to about 0.25 inches. The present invention eliminates the need to use shims to obtain a horizontally level tread48. By “shim” it is meant a thin, often tapered piece of material, such as wood, stone, or metal, used to fill gaps, make something level, or adjust something to fit properly.

Once one of the treads48is secured in respective horizontally aligned notches36between a pair of stringers24, a small diameter pilot hole (not shown) can be drilled from the underside of the stringer24such that it enters into the semicircular periphery50of a given tread48. A countersink or counter bore (not shown) can also be formed about the exterior surface of the pilot hole. By “countersink or counter bore” it is meant a hole with the top part enlarged so that the head of a screw or bolt will lie flush with or below the surface. The countersink or counter bore is sized to receive a wooden plug. A screw, such as a wood screw or a lag screw, or a threaded bolt (not shown) can then be screwed into the pilot hole to securely fasten the tread48to the stringer24. A wooden plug is then inserted into the countersink or counter bore and is cut and/or sanded down to blend in with the semicircular periphery50of the tread48such that it becomes unnoticeable. The wooden plug can be of the same wood used to construct the stringer24. Alternatively, a pilot hole can be drilled down through the flat surface52of the tread such that it enters the protuberance44. A countersink or counter bore can also be formed about the exterior surface of the pilot hole. The countersink or counter bore is again sized to receive a wooden plug. A screw, such as a wood screw or a lag screw, or a threaded bolt (not shown) can then be screwed into the pilot hole to securely fasten the tread48to the stringer24. A wooden plug is then inserted into the countersink or counter bore and is cut and/or sanded down to blend in with the flat surface52of the tread48such that it becomes unnoticeable. The wooden plug can be of the same wood used to construct the tread48.

Referring toFIGS. 16-19, another embodiment is shown depicting a portion of a log stringer62having a longitudinal central axis X2-X2and a portion of a tread64having a longitudinal central axis X2-X2. In this embodiment, called the wedge design, an oval shaped protuberance44′ is formed in the log stringer62which is aligned perpendicular to the longitudinal central axis X2-X2of the log stringer62. In addition, an oval shaped opening54′ is formed in the tread64which is aligned parallel to the longitudinal central axis X2-X2of the tread64. The opening54′ is slightly larger in size than the protuberance44′ to allow for minor adjustments, if necessary. The opening54′ is intended to mate with the protuberance44′ to secure the tread64to the log stringer62. An adhesive or glue can also be used, as was explained above to form a more secure attachment.

Referring toFIGS. 20-23, still another embodiment is shown depicting a portion of a log stringer66having a longitudinal central axis X3-X3and a portion of a tread68having a longitudinal central axis X3-X3. In this embodiment, called the slice design, a protuberance44″ in the shape of a portion of a narrow disc is formed in the log stringer66and is aligned perpendicular to the longitudinal central axis X3-X3of the stringer66. In addition, a key shaped slot opening54″ is formed in the tread68and is aligned parallel to the longitudinal central axis X3-X3of the tread64. The opening54″ is slightly larger in size than the protuberance44″ to allow for minor adjustments, if necessary. The opening54″ is intended to mate with the protuberance44″ to secure the tread68to the log stringer66. An adhesive or glue can also be used, as was explained above to form a more secure attachment.

Referring toFIGS. 24-27, a further embodiment is shown depicting a portion of a log stringer70having a longitudinal central axis X4-X4and a portion of a tread72having a longitudinal central axis X4-X4. In this embodiment, called the notch design, a notch36′ is formed in the log stringer66which has a side wall74. The notch36′ is aligned perpendicular to the longitudinal central axis X4-X4of the log stringer66. The side wall74functions as a protuberance44,44′ or44″. In this embodiment, the periphery of the side wall74is flush with the outer circumference of the log stringer70instead of being inboard of it. In addition, a concave notch76is formed in the tread72and the longest dimension of the concave notch76is aligned parallel to the longitudinal central axis X4-X4of the tread64. The concave notch76is slightly larger in size than the notch36′ to allow for minor adjustments, if necessary. The concave notch76is intended to mate with the notch36′ to secure the tread72to the log stringer70. An adhesive or glue can also be used, as was explained above to form a more secure attachment.

Referring toFIGS. 28-31, still another embodiment is shown depicting a portion of a log stringer78having a longitudinal central axis X5-X5and a portion of a tread80having a longitudinal central axis X5-X5. In this embodiment, called the slot design, a protuberance82is formed within a concave cavity38′ formed in the log stringer78. The long dimension of the protuberance82is aligned parallel to the longitudinal central axis X5-X5of the log stringer78. In addition, a key shaped slot opening84is formed in the tread80and the longest dimension of the key shaped slot opening38′ is aligned perpendicular to the longitudinal central axis X5-X5of the tread80. The key shaped slot opening84is slightly larger in size than the protuberance82to allow for minor adjustments, if necessary. The key shaped slot opening84is intended to mate with the protuberance82to secure the tread80to the log stringer78. An adhesive or glue can also be used, as was explained above to form a more secure attachment.

Referring toFIGS. 32-34, a further embodiment is shown depicting a portion of a log stringer86having a longitudinal central axis X6-X6and a portion of a tread88having a longitudinal central axis X6-X6. In this embodiment, called the dowel design, a protuberance90is formed within a concave cavity38″ formed in the log stringer86. The protuberance90is in the shape of a dowel rod which extends outward from the center of the log stringer86and is aligned perpendicular to the longitudinal central axis X6-X6of the log stringer86. In addition, an aperture or opening92is formed in the tread88and the aperture92is aligned perpendicular to the longitudinal central axis X6-X6of the tread88. The aperture92is slightly larger in size than the protuberance90to allow for minor adjustments, if necessary. The aperture92is intended to mate with the protuberance90to secure the tread88to the log stringer86. An adhesive or glue can also be used, as was explained above to form a more secure attachment.

Method

A method of producing components for a log staircase22,22′ or22″ will now be explained. The method includes the steps of selecting a pair of elongated, dried natural logs. The logs can be conifer logs. Any bark that may be present on the logs is removed such that each log is free of bark. The logs can then be subjected to a peeling process where scraps are formed in the outer circumferences of each log to make it appear similar to a log that has been hand peeled using a draw knife. If the log staircase22requires a pair of stringers24, two logs of approximately the same outer circumference and diameter d are selected. No two logs will have a constant diameter but a relatively constant diameter will suffice. Each of the pair of stringers24has a length and an outer circumference which is relatively constant along its length. The outer circumference of one of the pair of stringers24will be similar in size to the outer circumference of the other stringer24. One or more notches36are cut or formed into the outer circumference of each of the pair of stringers24. Each of the notches36is longitudinally aligned with the other notches36and each notch36has a protuberance44extending upward or outward therefrom. Each of the notches36formed in one of the pair of stringers24is aligned horizontally along a common axis with one of the notches36formed in the other stringer24. The method also includes forming a predetermined number of treads48equal to the number of notches36formed in each of the pair of stringers24. Each of the treads48has a semicircular periphery50with a flat surface52. Each of the treads48has a pair of spaced apart openings54cut into the semicircular periphery50which are aligned at an acute angle to the flat surface52. Each of the pair of openings54is capable of mating with one of the protuberances44formed in each of the pair of stringers24. The method further includes gathering together the pair of stringers24and the predetermined number of treads48for shipment to a customer.

Optionally, the method can further include drilling apertures in each of the treads48such that the apertures are aligned with each of the openings or concave pockets54. The apertures can extend from the flat surface52of a tread48or from the underside semicircular periphery50of a tread48. A countersink or a counter bore can then be formed in the flat surface52of each of the predetermined number of treads48. Alternatively, the countersink or a counter bore can then be formed in spherical periphery50of each of the predetermined number of treads48. The countersink or counter bore will be coaxially aligned with one of the apertures and a wooden plug can be provided which can be inserted into the countersink or counter bore once a fastener has been inserted therein. The fastener will act to secure and retain the tread48to each of the stringers24.

The method can further include providing a number of fasteners which can be used to secure each of the predetermined number of treads48to each of the pair of stringers24.