Geometrical instruments – Gauge – Template
Reexamination Certificate
2002-09-12
2004-06-15
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Gauge
Template
C033S042000
Reexamination Certificate
active
06748668
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to carpentry. More particularly, the present invention relates to templates for routing stair stringers.
2. Description of the Related Art
The routing of stair stringers to receive stair treads and risers is widely used in custom carpentry for the installation of attractive stairways. Router template systems are known which provide for variation in riser height and tread depth, but are difficult to adjust and use. A simpler device is known which is relative easy to use and adjust for riser height and is reversible so as to rout opposing stair stringers without readjustment of the template, but is limited to a single tread depth. It would be desirable to provide a router template system which is portable, easy to adjust and allows for adjustment of both riser height and tread depth as well as tread thickness and is reversible to rout opposing stair stringers without additional adjustment.
U.S. Pat. No. 374,493, issued Dec. 6, 1887, to Parry, describes a template for gaining stair stringers using a molding tool.
U.S. Pat. No. 1,042,120, issued Oct. 22, 1912, to Kelley describes a template or guide device for use with routing machines to cut stair stringers.
U.S. Pat. No. 1,552,881, issued Sep. 8, 1925, to Rose describes a spindle molding machine for cutting grooves in stair stringers.
U.S. Pat. No. 4,605,048, issued Aug. 12, 1986, to Swartout et al., describes a reversible template for routing facing stair stringers without readjustment, however, the template is limited to a single stair tread depth.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a variable thread and rise stringer for stairs solving the aforementioned problems is desired.
SUMMARY OF THE INVENTION
The present invention is a router template for cutting mortises in stair stringers to receive stair treads and risers. The invention is generally triangular in shape and planar in configuration. The template defines a tread slot and a riser slot joining the tread slot at a right angle. The template body is useful for cutting complementary stringers routing a first stringer, flipping the generally planar body from one working surface to its opposite working surface, and routing the other stringer.
The template body has registration points slidably mounted within the template body to extend downward from the planar body when working from either working surface. The template has a tread registration assembly and a riser registration assembly and a clamp assembly, each positioned to correspond with the corner portions of the template body. The tread registration assembly is adjustable and determines tread length, and the riser registration assembly is adjustable and determines riser length. Each registration assembly is placed on the same edge of the riser and the clamp assembly clamps against the opposite edge of the riser to maintain the template in the desired position to rout a tread and riser. The clamp assembly is releasable for sliding the template body along the stringer and tightened at the desired position to make the next mortise.
The tread slot has scales to determine the length of the tread mortice and the thickness of the mortice to accommodate differing lengths and thicknesses of tread. The tread registration assembly is then set by moving it against the string edge and securing it once the tread slot scale determines the tread configuration. The riser slot has a scale to determine the length of the riser. The riser registration assembly is then set by moving it against the stringer edge and securing it in the manner of the tread registration assembly. Once set, the registration remains set during the routing of both complementary stringers. A router collar is selected which travels against the inner wall of the tread slot to cut the desired tread thickness. The body is preferably made of high density polyethylene(HDPE).
Slot inserts are provided for the tread slot for providing desired tread lip design and to provide a parallel slot for open tread routing and an angled slot for closed tread routing for use with a riser.
Accordingly, it is a principal object of the invention to provide a router template for routing stair stringers which is portable and easily used on the construction site.
It is another object of the invention to provide a router template as above which, once adjusted, is reversible so as cut complementary mortises for stair treads and risers in facing risers.
It is a further object of the invention to provide a router template as above which is adjustable to provide variation in both rise height and tread depth.
Still another object of the invention is to provide a router template as above which is adaptable to cut mortises for open stair stringers.
Yet another object of the invention is to provide a router as above which provides for cutting mortises for custom tread edges.
Still another object of the invention is to provide a router template as above with which cuts stringer mortises to fit a range of stair tread thicknesses.
Yet another object of the invention is to provide a router template as above which may easily be moved and positioned to cut a series of open or closed stair stringer mortises.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
REFERENCES:
patent: 374493 (1887-12-01), Parry
patent: 909636 (1909-01-01), Montgomery
patent: 1042120 (1912-10-01), Kelley
patent: 1552881 (1925-09-01), Rose
patent: 4605048 (1986-08-01), Swartout et al.
patent: 4769920 (1988-09-01), O'Connor, Jr.
patent: 6233835 (2001-05-01), Brown et al.
Bennett G. Bradley
Huff Randall
LandOfFree
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