Spiral stair case

A spiral stair case wherein segments of the outside stringer framework and segments of the central column are forming corresponding polygonal segments, wherein the spiral stair case preferably is made in octagonal polygonal segments, wherein one segment of the outside stringer together with one segment of the central column respectively is supporting preferably two stair treads of the the spiral stair case, wherein the segments of the outside stringer and the segments of the central column are strait, non curved elements, and wherein the stair treads are made strait and wherein all peripheral cuts are made strait, and wherein the segments are connected to each other by standard carpentry connection means, wherein the fascia, the baluster posts, the baluster filler parts and the handrail build the rigid outside stringer segments, wherein the outside stringer segments build a rigid, structural supporting outside stringer framework of the spiral stair case formed in polygonal segments and wherein the segments are connected to each other by standard carpentry connection means, and wherein the central column is formed open and wherein the top edge of the central column is functioning as an inside handrail for the spiral stair case, and wherein all single parts of the spiral stair case as the fascia, baluster posts, baluster filler parts, handrail, the central column segments, the treads, and the wooden splines and dovetail splines are made in standard carpentry craftsmanship with standard carpentry tools.

BACKGROUND OF INVENTION 
This invention relates generally to spiral stair cases, made of wood or 
similar, comparable materials. 
Spiral stair cases are old and well known. They are usually supported on 
the central column where it is necessary to provide special attachments to 
support the treads and/or specially made treads and where the peripheral 
edges of the treads are unsupported, or mostly supported only to a limited 
extent, and when they are supported on the outside, then with a circular 
stringer made from metal or laminated wood, which is not very rigid and 
stable and which is more labor intensive to produce. 
Those structures tend to swing and wobble in use, giving a feeling of 
insecurity to the user. Especially in private residences where some house 
designs require spiral stair cases, there is a need for a solid and 
tastefully designed spiral stair case made out of wood or similar, 
comparable materials and which is simple in design and can be produced 
with standard carpentry means and tools. 
SUMMARY OF THE INVENTION 
It has been found that a spiral stair case of wood or similar, comparable 
materials can be made in polygonal segments wherein preferable always two 
treads are set into one segment of the outside stringer and accordingly 
into one segment of the central column, wherein these segments of the 
outside stringer and accordingly the segments of the central column are 
forming corresponding polygons. Baluster and handrail build together with 
the outside fascia one rigid, frame like unit, and this single units 
attached to each other forming a rigid, supporting outside stringer 
framework of the polygon segments formeing spiral staircase. The most 
practical form is a spiral staircase made of polygon segments with 8 sides 
wherein variations between 6 and 12 sides maybe useful in some situations. 
Those spiral stair cases are very solid and rigid and submit a secure 
feeling to the user. Furthermore these type of spiral stair cases are 
easily prefabricated in the said stringer segments, column segments and 
treads and because there are non curved elements and no special 
attachments or brackets necessary, the fabrication is simple and 
inexpensive and so is the assembling and installation.

REFERENCE NUMERALS IN DRAWINGS 
10 outside striger segments 
10a beginner segments of the outside stringer frame work 
11 facia 
11a blind grooves in fascia 
11b notches in fascia 
11c groove in fascia 
12 handrail 
12a groove in handrail 
13 baluster filler parts 
14 baluster posts 
15 beginner baluster post on the outside stringer frame work 
16 central column 
17 standart central column segment 
17a notches in central column segments 
18 beginner central column segment 
19 beginner central column segment 
2O tread 
21 screw 
22 bolt 
23 wooden spline 
24 wooden dovetail spline 
25 allthread bolt with washer and nut 
25a rosette 
26 standard metal ankle bracket 
27 standard metal base plate 
DESCRIPTION OF PREFERRED EMBODIMENT 
Referring now to the drawings in detail (FIG. 1), there is provided a 
standard metal base plate 27 to distribute part of the weight of the 
spiral stair case and to anchor the central column 16 to the floor. 
Respectively there is a standard metal base plate 2 7 to distribute the 
main part of the weight and live lead of the spiral stair case and to 
anchor the outside stringer frame work 1 0 to the floor. The central 
column 1 6 has the polygon segment configuration shown with 8 sides (FIG. 
2), and so has the outside stringer frame work 1 0. The treads 2 0 are set 
in blind grooves 1 1a (FIG. 3a) in the fascia 11 and the central column 
segments 1 7, 18 and 1 9. Every second segment there is an all-thread bolt 
with washer and nut 25 bracing the spiral stair case and holding together 
outside stringer frame work 1 0 and central column 1 6. The wooden rosette 
25a covers the nut and washer of the all-thread bolt 2 5 for decoration. 
The top of said spiral stair case is mounted with the standard metal ankle 
brackets 26 to the next floor or respectively landing. 15 is the beginner 
baluster post on the outside stringer frame work (FIG. 1). 18 and 1 9 are 
the beginner posts on the central column (FIG. 2 and FIG. 4). 
Referring to (FIG. 2), there is shown a top view of a typical situation of 
said spiral stair case. The treads 2 0 together with center column 16 end 
outside stringer frame work 10 are building one structural frame like unit 
glued and bolted together with standard carpentry connecting means. The 
end, respectively the beginner segments of the outside stringer frame work 
1 0a are mostly half segments and then only carry one tread. 
(FIG. 3) shows two outside stringer segments 10 composed of fascia 1 1, 
baluster posts 14, some baluster filler parts 1 3 and handrail 1 2. These 
baluster filler parts 13 can be made in variations as shown, in all kind 
of artistic designs, or with standard baluster stacketten, or with 
security glass or similar materials. 
(FIG. 3a) shows a perspective view of the fascia 1 1, with the blind 
grooves 11a to hold the treads 20, the notches 11b to attach the baluster 
post 1 4 and the groove 11c to attach the baluster filler parts 1 3. The 
outside stringers 1 0 are connected to each other with wooden splines 23 
and screws 2 1 as shown in (FIG. 5), cross section A--A. An alternative 
with wooden splines 23 and bolts 2 2 is shown in (FIG. 5a), and another 
alternative shown in (FIG. 5b), connects the outside stringers 10 with a 
wooden dovetail spline 2 4, all connections are glued in a craftsman like 
manner in addition to the shown connectors. 
(FIG. 4) shows part of the central column 16 with a standard central column 
segment 1 7 and beginner segments1 8 and 1 9. It shows the notches 17a to 
hold the treads 2 0. These segments are connected to each other with 
wooden splines 23 and screws 2 1 as shown in (FIG. 6), cross section B--B. 
An alternative with wooden dovetail splines 24 is shown in (FIG. 6a). All 
connections are glued in a craftsman like manner in addition to the shown 
connectors. 
(FIG. 7), shows the cross section C--C through the spiral stair case. It 
shows the connection between the outside stringer frame work 1 0 and the 
central column 1 6, wherein the all-thread bolt with washer and nut 25 and 
the treads 20 are the connecting elements. Wherein the treads are sitting 
in the blind grooves 11a in the fascia 11 and respectively in the notches 
17a in the central column segments 17, 18 and 19. The handrail 12 is 
attached and glued to the baluster filler parts 13 in the groove 12a, and 
so are the baluster filler parts13 to the fascia 11 in the groove 1 1c. 
The baluster posts14 are glued into the notches11b in the fascia 1 1. 
The foregoing description is merely intended to illustrate an embodiment of 
the invention. The component pads have been shown and described. They each 
may have substitutes which may perform a substantially similar function: 
such substitutes may be known as proper substitutes for the said 
components and may have actually been known or invented before the present 
invention. These substitutes are contemplated as being within the scope of 
the appended claims, although they are not specifically cataloged herein.