Yin-Yang Sun & Moon Tensegrity Table

Even once you know the physics behind tensegrity, this table still feels like it should be falling over. After all, surely you can't hang the top of a table from the bottom, right? And yet not only does it stand up, but it can support weight-- up to <weight goes here>!

Making this was a team effort. I created this alongside Nathan Traut. Here's a link to his page.

This project requires some small hooks and string to build. You can buy the hooks at <link here>.

Problem Statement

With a partner, you will design and create a single custom Tensegrity Structure.

Parts List

Below are the printed parts needed for this assembly, along with the quantity you'll need of each.

Jathan_CloudsBase --->           1

Jathan_StarsBase --->              1

Jathan_SunBeam --->              1

Jathan_MoonBeam --->           1

Assembly Instructions

Recommended tools: Hammer, very small Phillips head screwdriver, flush cutters, scissors, pencil, ruler with mm, sandpaper

Additional parts needed: 8 small metal hooks (link to buy), fishing line or other string (approx. 135 cm)

Step 1: Gather materials

Gather all materials including tools, and print all parts from Solidworks file.
 

Step 2: Insert hooks into bases

1. Pick a mark on one of the bases. Take a pair of flush cutters and attempt to dig a hole starting at that mark. This part is tricky--you need to push hard enough to make a hole, but if you go too hard, the hole will become too big and the hooks won’t stick.

1. Attempt to push a hook into the hole you’ve made. If it can stand up on its own, move on to the next step. Otherwise, repeat steps b and c until it does.

1. Once the hook can stand up on its own, that’s a good indication that your hole is a good size. Now screw the hook in until the entire screw is buried in the base, leaving only the ring poking out. This will be quite difficult if your hole is small enough, you may need pliers to hold the hook while you screw it.
2. NOTE: It may be easier to hold the hook in place and spin the base around it, rather than the other way around.

     5. Repeat steps a-d for each mark.

Step 3: Insert hooks into beams

1. Take one of your two remaining hooks. Use a pair of flush cutters to cut away a small piece of it, turning it from a ring into a hook.

1. Putting in the hooks is the same as for the bases, with one note:
   1. Be VERY careful making your holes this time! Because of the direction the pieces were printed, these holes will be pushing apart the layers of the print. If you’re not careful, you can split the piece open.

1. You should now have all 8 hooks inserted into the proper pieces, and are ready to move on.

Step 4: Putting the pieces together

1. Take your moon piece and stars piece. Insert the tab at the bottom of the moon piece into the slot in the stars piece so that it hangs over the center.
   1. It may not fit off the bat. If it doesn’t, try:
      1. Pushing harder. Sometimes, it can just barely fit, which is good because you don’t want these coming apart.
      2. Sandpaper. Sanding it down can make it just small enough to fit.
      3. Flush cutters. You can chop off the edges of the corners where the filament juts out.

1. Repeat with the sun and clouds.
   1. IMPORTANT NOTE: The sun piece inserts into the bottom, flat side of the clouds--the same side you put the hooks into.

Step 5: Achieving Tensegrity

1. Prepare the string.
   1. Cut your string into 3 approximately equal segments, each ~45 cm long.

1. Connect the two hooks on your sun and moon beams together. You should be hanging the sun piece from the moon piece, which will put the clouds on top.

1. Now comes the hard part. You’ll need two people.
   1. Have one person hold the clouds piece in an upright position. You may also want to pin the stars piece in place against the table.

1. The other person takes a piece of string and loops it through a corresponding pair of hooks on the stars and clouds pieces, and then ties the two ends of the loop together.
   1. Make sure to pull the string as tight as you can.

1. To tie this knot, we recommend you use a square knot. Here is a link to a video on how to tie a square knot, but we also have instructions below.
   1. Hold the two ends of the string, one in each hand.
   2. Cross the string in your left hand over the string in your right hand.
   3. Loop the left-hand string under the right-hand string, switching hands as you do.
   4. Repeat steps 1-3 again.
   5. 
2. Repeat the process for the other two strings.

1. At this point, the first person should be able to let go of the top, and you’re finished!

Design Choices

When we first came up with the idea for this project, it was a lot simpler. A simple yin and yang, the sun and moon were nowhere to be found. One of our first changes came when we realized that this was far too simple a design, and we needed some more detail. So the sun and moon were added. Then we noticed that the top and bottom pieces were also looking very bland, and decided to add yin-yang symbols on them as well. The idea for the stars and clouds came here as well.

That was the status when we first started to model these pieces. For the most part, we stuck to that design, although there were a few changes. This was the period where we came up with the idea of the groove around the border of the sun piece, and it was also when our teacher introduced us to the Freeform tool. This is what let us have the bumpy terrain on the Moon and Stars pieces. One other change that was made here was to move the large stars on that base to coincide with the hole--previously, they were set off to the side.

That was hoe we printed our first draft and put it together. It worked fairly well, but there were a few problems, which we fixed in the final draft. One was that the hooks were difficult to insert into the various pieces--we didn't have pre-made holes yet. We also changed the clouds, making them smaller so we could fit more of them. A final aesthetic change was to make one of our star shapes smaller--it had been drawing too much attention.