Thursday, June 10, 2010

Universal bracket plate





I've been developing a modular building system which uses rhombic dodecahedrons (RD) as the basic module. The only present method, which stabilises what would be a very wobbly RD structure, is to use pre-fabricated rhombic panels which are then edge joined.

However, I wish to build  RD structures using only post and beam construction technique.
I believe that the natural strength of a structure comes from inside not from the exterior shell.

However all of my previous methods I had used to join the posts to the beams had proved to be less than satisfactory.

Tenons, dowels, screws, various brackets had all failed me.

I finally came across an elegant solution.

A six way connection, hurricane tie bracket specifically designed for a modular building system based on rhombic dodecahedra using post and beam technique.

This product is patent pending. Filed on the 19th April 2010.

http://www.patentauction.com/patent.php?nb=5629

Description of Invention.
A heavy duty metal plate that when interconnected with five other identical plates becomes a 6-way, hurricane tie bracket specifically designed for a modular building system based on rhombic dodecahedra using a post and beam technique rather than using panels to create stability.

Typically the beams or rafters, in such a system, are connected to a six-way bracket which is in turn encircles a hexagonal cross sectioned post.
This invention solves the problem of the post to beam connection when building rhombic structures.

There is no satisfactory connector system available which can join six sloped rafters midway along the length of a hexagonal post. One could use six individual, variable sloped brackets on each face of the hexagonal post. The sloped bracket is more suited for uplift forces rather than tension forces. There would be over-nailing problems and inaccuracies in setting the required angle of the rafter to the post at 109.5 degrees. (The reflex angle of the rhombic in a rhombic dodecahedron).

The invention consists of six identical, preformed, metal plates each of which have two slots. The slots are used for interconnecting purposes. Each plate when alternatively interlocked, interconnect the six metal plates into a hexagonal ring creating a strong, 6-way, rigid bracket that encircles the hexagonal post. It can be slid up or down the post to allow for final field adjustment, whereupon it can be affixed to the post using minimal nailing.
Plate Design
The bracket plate is water jet or laser cut out of flat sheet (10 gauge?). The width of the bracket plate is configured and designed to accommodate various dimensional lumber or hollow tube to fit in or around the ends of the plate. The flat bracket plate is somewhat chevron shaped wherein the reflex angle is 109.5 degrees at both ends. The bracket plate has two parallel slots distanced equally apart about the mid-line of the plate . The distance between the centre lines of the slots is equal to the width of the rafter or beam plus the thickness (gauge)of the two plates. The plate is then folded as shown in Figure 3 at angles of 150 degrees. The area between the slots at the centre of the plate is pre-drilled with holes to accommodate attachment of plate to hexagonal wooden post .

How the Invention Works:
A single bracket plate is nailed to a vertically positioned hexagonal cross sectioned post 10 (See Figure 8) so that the slots are facing upward and plumb. A second plate with the slots facing down is interlocked to the previously fixed plate , leveled and fixed. A third, fourth and fifth plate is attached in similar fashion. The sixth plate is lap-jointed to both the first and fifth plate completing a hexagonal ring structure. The resulting bracket offers six locations for attachment of beam or rafter member. Timber rafters, typically 2X’s, can be sandwiched between the two parallel inclined plates of the assembled bracket.

Hexagonal posts Hexagonal wooden posts are easily manufactured using standard sized lumber. The modular system that is envisioned will be using mainly 2 by 4’s,6’s and 8’s .


Why?

The rhombic dodecahedron is a more efficient structural shape than an orthogonal or cubic shape. An ideal structure would enclose a large amount of space with a small amount of building material. Cubes have a low volume to surface area ratio. Of all three-dimensional shapes, the sphere has the highest. The closer a building is to spherical, the better it is able to withstand high winds and weather conditions. The rhombic dodecahedron perfectly packages a sphere. It tessellates three dimensional space. The structures that, only now, are able to be safely built by the use of this product could initiate a growth market because of its possible green appeal.
Companies that accept timber for recycling back into the building trade will generally not accept anything less than 6 feet in length.
A timber beam length of 5 1/2 feet will make an approximate rhombic dodecahedral room area of  67 square feet. (9 feet flat to flat / 10 feet point to point)
Its simplicity of design indicates a low manufacturing cost and therefore an acceptable price tag.

A new way, using low tech, energy efficient, easy construction techniques to build strong hurricane /tsunami annealed housing units.




The beauty of this bracket is that it totally simplifies the construction process of what would have been a very complicated and somewhat inefficent structure to assemble.
Initially I was planning hardwood dowels to join the posts and beams together. This, as previously stated, was too questionable as most of the joints would be subject to tension forces.
No need to know this now!!!!
Designing the necessary dowelling jigs took the project beyond the scope of  homebuilders.
Now the only main tools required are a laser level, hammer and saw. Let's get building!!!