Saturday, November 7, 2009
Wired Magazine has published a full page on O2 Treehouse and our latest creation. The 20' diameter (1-4) deltoid reticulation. Consisting of 210 openings and 420 facets. Each opening is constructed from an individual tapered deltoid created of 1 x 6 red wood. The custom diamond and printed floor is created from cut-offs from the deltoid construction. Read more for a detail explanation of triumphs and tribulations of how it came to be!
I used 3/16" steel hubs with flanges welded together in the center. These had to be very very accurate to match the deltoid tapered constructions. We had a problem with the welding because after each weld was made when it cooled it pulled the flange out of position. We were able to correct this by creating a jig and putting the hub in a vice and custom bending each flange back into position using a template as a guide.
I created each deltoid as a separate unit ( a construction technique I will never attempt again. It gave me the all wood joint center that I so desired and created a beautiful reveal between each shape ( thickness of the hub flange ) but was quite a task. I wanted to farm out the the wood cutting to a cnc house but most shops gave me a stink bid because it was to complicated for them to want to wrap their heads around and to great a possibility for error. The only shop of which I found that had the proper equipment was a boat building company. Lucky for me I was constructing it in Huntington Beach CA. In the end it was me and one solid week of cutting on the finest digital chop saw I could find. I created 19 custom jigs. Each jig had a 1/2" pin on it which corresponded to the whole in the wooden plank. I cut both angles of the compound angle simultaneously. I batched each individual plank of course so I could do the whole structure's worth of that particular board. Even with the jigs and the digital gage it still took constant checking and a keen eye on the woods edge. A 1/6th off was unacceptable because as you know these errors compound.
I then hired a team of assemblers. We glued, air nailed, and screwed every joint at a prefab location. Then we packed everything up and shipped to site. The floor structure was created around the tree first which transfers the load of the sphere into the ground directly around the trunk. The floor structure has a center girdle that has telescopically rods that press against the tree with a soft wood foot. Once this was secure we stared assembly of the sphere around the floor structure by cabling into the hubs in about 30 places before we crested the edge of the floor. From this point on it was easier construction standing on the deck until we started coming in contact with tree limbs. I usually take the wait and see approach with limbs and have gotten lucky with this technique even throughout this build. No joint customization took place it all slipped, barely, through the structure. We fought gravity througout the entire process constantly fighting the structure together. Parts that needed to come together which looked impossible did eventually come round with some coaxing.
It was amazing when we put the last piece on, the pumpkin top. It dropped right in! To our glory and amazement all the bolts dropped in as well. It was an incredible amount of work don't get me wrong but sweet to see it all come together. The floor is constructed using all the scrap cut offs from the sphere creation which was a nice touch for the interior. We dropped as many cables as we could into the top supported via upper branches. Hopefully this will fight gravity enough to keep the joints from settling over time. The structure is treated and sealed with three coats of a five year warranty sealer.