Yet Another Tensegrity Stand (YATS)

[dejoha]

While I was awaiting some amsteel for my other tensegrity stand, I thought I would try to build a new design that Blackshadow mentioned. An emergency trip to Utah provided me the opportunity to try something out.

My two requirements for a stand are 1) inexpensive, and 2) easy to construct. This new stand meets the first requirement and I would say it is moderately easy to construct.

I used the instructions from bweebweebwee.com and found the design to be rock-solid, even with cheap rope. Here's what I did to construct this stand this past weekend.



Yet Another Tensegrity Stand (YATS, pronounced "Yahtzee!")

MATERIALS
3 - 2" x 3" x 8 ft boards @ $1.50 ea -- $4.50
6 - 3 ft rebar for stakes @ $1.35 ea -- $8.10
~250 ft of rope (I purchased 300 ft of 3/8" poly rope; 100 ft @ $8 ea; 3 different colors)

I purchased everything at Home Depot for about $36, just under the "too expensive" radar.

CONSTRUCTION
After arriving at my relatives, I borrowed their tools and drilled two 1" holes on the top of each board and one 1" hole at the bottom. After building the stand, I realized I needed better attach points for the hammock so I drilled a third hole (1/2") on the top where I placed a dowel.

The top triangle is constructed of 14 ft lengths or rope. For the top triangle, I left it as one continuous line, with some extra length to tie the truckers hitch -- about 50 feet total.

The side and bottom ropes are both 10 ft 7 inches long. I cut each of these at 13 feet, to allow a few inches to tie knots.

I took each rebar and bent one end into a crook shape.

SET-UP
1) Set up the stakes in a hexagon shape. The radius should be 14 ft. The easiest way to do this is to have two 14 ft strings. From the center point, measure out for your first stake point with the first string. From there, use the second string from the first stake and the string from the center point to determine the next stake point. Use this pattern to determine the six stake points.

2) Tie off the side and bottom ropes. I just used two half-hitches on both ends. I think it is important to the structural integrity that the side ropes are single ropes, but the bottom rope could be a continuous rope about 24 ft long that threads through the pole.

3) Thread the top rope through the top holes. Pull the rope to take up the slack and the stand will rise. I tied a figure-8 on a bite on one end and used this as the anchor point to tie a truckers hitch to get the structure taut.

I made some minor tweaking in the knots to make sure the posts were at a 60° angle.

[UncleMJM]

Very nice. Great job on making it look simple.

[CajunHiker]

Nice.
Do you think it could be shortened up a bit?

[dejoha]

Do you think it could be shortened up a bit?

Do you mean the side and bottom ropes? The strength comes from equilateral triangles on each side, which also helps achieve the 60° angle on the struts -- everything is equilateral triangles.

You could experiment with shorter side/bottom ropes, but I don't think it would hold. This is a very solid design.

[NCPatrick]

Nice.
Do you think it could be shortened up a bit?

Do you mean the side and bottom ropes? The strength comes from equilateral triangles on each side, which also helps achieve the 60° angle on the struts -- everything is equilateral triangles.

You could experiment with shorter side/bottom ropes, but I don't think it would hold. This is a very solid design.

I took this to mean whether you could use shorter than 8 foot boards...

Very nice, btw!

[CajunHiker]

I took this to mean whether you could use shorter than 8 foot boards...

Right. If the top triangle was reduced to say 12' sides, you could move it downward on the boards keeping the same angles. This would also shorten up the outer triangles.

[Talox]

So I just put together a YATS to give me a little more flexibility as to where I hang, be it in the backyard or campground. I decided that I wanted to use eye hooks and carabineers to simplify setup and storage. The lines are 3/16 Amsteel with locked Brummel eye splices at each stake point and a carabineer held in place with clove hitches at the 2x3 anchor. I’m still not sure if my stakes are secure enough I’ve been using 24” lengths of ¾” rebar and or 15 “ plastic stakes. So far nothing has moved but its just a point of uncertainty.

I used the ultimate Hang calculator to run some rough numbers which don’t look too bad <200lbs horizontal force splits amongst 4 stakes with me hanging @210 I suppose if i want to lessen the angle on the stakes i could extend the rope form the top of the 2X3 and move the stakes back a few feet.

[dejoha]

I took this to mean whether you could use shorter than 8 foot boards...

I suppose you could. It would mean figuring out new, shorter lengths for all the ropes. But here is another thing to consider: Once that 8 ft board is leaning at 60°, the total height is not much higher than 7 ft, which is a perfect hanging height for a distance of 14 ft to give the hammock the right 30° hang angle, etc. It all works out very nicely.

You could use other materials like metal fence posts and use couplers to combine two, 4 ft lengths, for example, but I think this is overkill. This stand isn't anything I would want to backpack with and 8 ft is easily transportable; it sticks out a bit in the back of a pick-up truck, but it's not much, and it fit fine in my van. I guess it's all about what you are trying to achieve with shorter struts.

[WV]

Terrific! (As in, "Yet Another Terrific Stand" - it's not exactly a tensegrity prism, but you could argue that tension holds it together, or holds the ends apart, or something .... )

I agree that it could be smaller. Are there any hammocks that really need more than a 10-foot span in which to hang? I also agree that the way to scale it down is just that - scale it down, so you retain the 60 degree angles. Geometry is your friend.

[thekalimist]

building this in near future,

thanks dejoha, you always make it looks so easy.