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Comment by jgtrosh | Hacker News Reader

Good to know the original inventor of tensegrity envisaged it for its real purpose: pretty toys to look at, instead of the grand engineering revolution it was touted as.

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On the other hand, there are some niches where compression tension, aka tensegrity, may have a practical utility. For example, the current lightest hammock stands are inspired by it. The HandyHammock stands [1][2] use cords to reduce the weight of the poles. Sadly, that model is not manufactured nor sold anymore. The small company Tensa Outdoor makes and sells the Tensa4 [3] which is based on an equilibrium with poles and guy lines. They also have plans for a DIY version [4], called tensahedron stand. The DIY 3-person Hammock Stand from The Ultimate Hang is also inspired by tensegrity [5]. The 3-Pole, 3-Person Tensegrity Stand (DIY) is even more impressive [6].

Although none of them are floating like in the sculptures, the concept and the art inspired some practical constructions.

[1] https://www.ddhammocks.com/images/products/_ALL_PRODUCTS/Ham... [2] https://theultimatehang.com/2012/12/11/handy-hammock-stand-r... [3] https://www.tensaoutdoor.com/product/tensa4-hammock-stand/?v... [4] https://www.tensaoutdoor.com/make-your-own-tensahedron-stand... [5] https://theultimatehang.com/2013/04/02/3-person-hammock-stan... [6] https://sectionhiker.com/portable-hammock-stands-for-camping...

Those hammock stands look pretty cool. I met someone who was experimenting with making his own tables this way. Here's some links [1] [2]

[1] https://www.copper.org/consumers/copperhome/DIY/cu_tensegrit...

[2] https://beltsandboxes.com/top-5-diy-impossible-tensegrity-ta...

I like tensegrity structures as sculptures and engineering exercises, but do cringe when I see attempts to make things like tensegrity footbridges applying these forms too literally.

There have been some neat robots that walk by changing the cable lengths though.

Viewed through a slightly fuzzy lens we are doing the same thing.

I've had fun building several tensegrity sculptures and I agree that it makes me very wary about bridges built on the idea. They have very unintuitive properties that are difficult to appreciate by just looking at them. They appear to be rigid but are actually springy and without pretensioning they are a floppy mess. It seems to be very non linear too with the structure lacking any rigidity as you tension and then snapping into place at the very end.

There are some very interesting similarities between tensegrities and bio mechanical structures. I used to think of bones as the scaffolding that holds up my meat parts but it's more like the meat parts and the bones work together as a tensegrity structure.

How can I learn to build tensegrity sculptures? Is it something impossible to do without schooling or master-apprenticeship?

You can get started with some rubber bands and soda straws. You just need a lot of patience. That will get you started but there are a limited number of things you can do with that and the rubber bands won't last being under constant tension and will eventually break. It takes a surprisingly small amount of materials, just something for the struts like dowels and some string. The most difficult thing is choosing how to attach the strings to the rods. It takes a lot of adjustment to get the pretensioning correct so you need something that you can change until you get it where you want it.

for a cheap start, chopsticks and twine work just fine.

Do a search for "tensegrity rods two-nails fuller mailing list" seems to produce a fair number of hits.

Also see:

It’s a fun puzzle. The main thing is to only connect the ends of the rods to cables and not to another rod.

This means the rods are under compression only and the cables carry all the tension. That’s the basic idea.

Additionally they tend to avoid the rods even touching, so that it gives more of an illusion of floating elements.

For something like a rubber band the challenge is that it will tend to pull itself apart before you get the final band attached. For cables that don't stretch the challenge will be it will be a gigantic tangled mess until you tension it. I have no idea how Snelson managed to construct the larger sculptures without killing himself.

There is/was a cell biologist, Don Ingber, pushing the idea that cells use tensegrity for their overall structure:

https://journals.biologists.com/jcs/article/116/7/1157/27541...

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