Sunday, May 25, 2025

OT tensegrity table

 So, I've been sitting this winter watching YT videos and ran across this guy making a massive steel tensegrity table. I'd never heard of them. I went online and looked up more about them and decided to try to make one.

My first try was pretty poor. I made some round circles and did this elaborate thing with old bicycle spokes. It worked and was a learning experience.




 The wood was too thick and the spokes too flexible.

So I set off on mod 2 mark 1. I used some thinner plywood 1/4" I had and cut some 5" circles. I had the idea to inlay some glass circles and hearts. I got these online. I used a circle cutter to cut the outline for the circle and the center section.

Using a router bit stuck in my drill press I was able to cut out the relief for the inlay. This was the hardest part, physically taxing on my hands to hold the wood in place. The bit stayed still and I moved the wood.  The circle didn't take long, but the hearts meant a lot of material removal.









Next I had to figure out the braces. This also took some time and 3 different designs until I found an A shaped design that held steady and was replicable. The ones below sunk in the wood with the tension and leaned.



This was one of my test mules.



The "A" frame brackets didn't lean.


Then I spent some time trying to figure out a more elegant brace. One of the hard things was trying to find the center point for the hanging chain. Not being mathematical  it was kinda point and shoot for me.

I finally came up with an idea and it works. 



It looks a little crooked because I needed to tighten the center chain.

Yep, it's small but it's kool!




Now I need a bigglyer one!

Starting with a piece of 15" x 11" x 1/4" glass and 3/4" square steel tubing I cut and sanded 2 identical sets of bars for a top and bottom.



My thought was to put some brass rod in the top to hold the glass so the glass and steel surfaces matched. I had 3/8" brass rod and using a test mule was able to ascertain where the holes needed to be drilled and what size holes to drill!

Test mule #2.




Setting up a jig and measuring out matching points on each tube I drilled all the holes.


This way I wound up with a top and bottom frame.


I'm not usually meticulous, however I did learn with the first tables I needed to be now. I carefully matched the top to the outside of the glass making little room. Then welding the tubes squarely together.



The bottom and top were welded up.


Next I marked out where the hanger loops would go and the hanging braces. For loops I chose medium screw eyes from ACE. These have a 55# rating and are steel so I could weld them in place.




No I pondered the hanging braces, The hardware store was out of tubing so I had a few days to think. I wrapped the spot for the braces in tape and gave the rest of it a coat of paint to keep it from rusting. And thought, and thought.

Knowing I had to just put it together since I don't have the maths to figure it out I needed more tubing to finish it.

Meanwhile I cut 6 pieces of the brass rod at iirc 2-5/16" and chucking them up in my drill, rounded the end which would sit under the glass.



Then the tubing came in. I clamped my ends to my welding table on  a sheet of plywood and drew an outline so I could relocate it easily. I needed to locate the center and work out lengths and angles, so it came to me to use string on the chain loops to find the center and figure out the angle from that. It worked out to be 25°. I cut 2 pieces at 14" with one end 30°. These I welded to the frames and set about figuring out how long an extension into the center would need to be.




I saw that I could cut a 3" piece and weld it onto the bottom of the angled tube and this would make a graceful angle at the bottom.


After grinding and sanding I painted them.


25 May 2025

   I splashed a couple of coats of paint on it and when they were dry enough I hammered in the brass rods. Hammered because I drilled the holes at 23/64" or 1/64" smaller than 3/8" . I wanted to have them tight so hopefully they won't walk out and with holes in both sides of the tube they would stay level.



That caused a little scuffing on the frame so another round of touch up paint was added. Whilst that dried I put some self sticking felt pads on the bottom frame.


I was excited! now I only had to work out the chains. I knew I wanted some 9' of chain for the center as this would put my table top at around 18" above the floor.



Nine inches of chain was cut and put in the middle. I had the frames on their sides and pulled them apart. A length of chain was connected to one eye and stretched to the other side eye. This seemed to work so I did that length 3 more times. Next I stood it upright. It was a little wobbly, so I took one link out of the center span. That made it less wobbly, but I needed even less wobble. Not being able to take more from the center I shortened the side spans by 1 link each. This was tight and required some pulling to get all attached. 

The table was firm though! I moved it off that worktable and tried the glass. Perfect fit! Now the glass needed cleaning before pictures and bringing in the house. A quick wipe with cleaner on both sides and viola!!!






Now I have a unique homemade coffee table.