So not necessarily glowforge style, but something I’ve been obsessing over lately. Tensegrity, for those who don’t know, basically means that there is opposing tension constantly pulling apart at each other, causing a floating effect.
This picture was my first go about it to kind of get a feel for how it works and where I can improve.
It was a little unstable and wobbled side to side. I used 550 cord to attach the top and bottom, though no wood from the top is actually touching the bottom. Because of the stretching in the cord, the single tension point stretches a little, causing the other tension points to become loose. First thought was remove the stretching material.
I decided to go with braided cable, nothing to serious as it won’t need to hold much weight, paired with the idea the load will be shared with 4 tension points, essentially quadrupling the strength of the overall build.
I also realized with the size of the wood I originally used, the stress points at the base of the L-shaped piece was overbearing the screws. I decided to upgrade from a 2x2 to a 4x4 for the L brackets and sunk the screws in from the bottom about 3/4 inches into a 2x4 board. This, of course, was all drawn up ahead of time (forgive pixelation)
After a few more tweaks to where I could see issues arising, I began my build 3 days ago. As of yet, I haven’t finished it as my wife and I are remodeling to have a nursery, so I wasn’t able to focus on the build. I’ve decided to assemble before I finish so I can make sure to make adjustments before having to change/add more and refinish to match. This is where I’m at so far but it is surprisingly sturdy for only having 3 out of 12 supports put together! I’m excited to see how it turns out.
So am I. It would make a wicked cool accent or coffee table. Otherwise I find the tensegrity stuff interesting but not compelling - like art without utility. This has both.
I wonder how it would work made out of plate steel or a combination of plate and square tubing.
I’d want to do it with less robust looking tensioning wires than chain. As you say, it would seem to be less mystifying with something like chain. It’s not really, but chain looks like it’s got mass & support vs thin cording or wire.
A lot of it is when you look at them you first don’t really think it’s that big of a deal because the parts are all connected. Then you realize that there’s no way a string can be holding the thing up because string/cord is floppy and the thing should be collapsing on itself
Of all of us you might have inside knowledge of medieval arming pavilions and how they manage to not have a center pole yet used a pulley in the center to lift a man in full armor on to a horse that would be hard to have the horse in there if there had been a centre pole.
Tensegrity seems a likely answer, but perhaps you know differently?
I don’t know the details. huge plow horse, extra 100+ pounds of armor (200+?). The drawings and paintings show very tall and narrow and do not show center poles. Artistic licence? That is one argument, but does not account for the horse.
I built a small version, poles to push out against rope or cloth to pull in, The cloth walls/roof were a major stabilizing part of the structure as rope alone is not
The use of pulley systems in tents to help knights mount their horses is actually a myth. They were never used historically outside of the movies. Armor for mounted combat was lighter to allow for maneuverability and finesse in combat. That being said, the idea somehow came across in the movies in the 40s, even against the information given by an historian they used as a consultant
