PVC Tensegrity "Pipe Burst"

Tensegrity! An object made from drain pipe leftovers! It's a bit magical how the physical conditions create a tension that makes it a unit. At first sight a bit confusing ... you have to look twice to understand the principle.

The trigger for this project was the "PVC“ - Speed Challenge!

I still had some drain pipes left over from a bathroom renovation. For example a toilet bowl connection piece (Ø 110 mm), a wrong buy because the angle didn't fit ... and a lot of drain pipe pieces (Ø 40mm). Enough material to realise my idea! 

Furthermore, I needed

• Metal saw
• Miter saw
• PVC glue
• Sandpaper
• Cutter knife
• Nyon thread Ø 0.35mm
• Preserving jar rubberring
• Sewing needle
• 4 screws Ø m 2.4 x 12 mm and matching nuts
• Drill bits Ø 1mm and Ø 2,5mm
• Screwdriver
• pliers

For this step I needed:

• PVC pipe Ø 110 mm
• Metal saw
• Cutter knife
• Sandpaper

From the white connection pipe for toilet bowls (Ø 110mm) I sawed 2 rings of 30mm width.

As this pipe does not fit into my miter saw, I had to use a normal metal saw for it. It was not easy to saw absolutely right-angled with it. Then I cleaned the edges with a cutter knife and sandpaper.

For the next step I needed:

• about 70 cm PVC pipe Ø 40 mm
• Miter saw
• Cutter knife
• Sandpaper
• PVC glue

I sawed 2 tubes to size 175 mm length. One side straight cut (90°) and one side 45° cut and 2 tubes to size 115mm length. Both sides 45° cut.

Again, I cleaned the edges with a cutter knife and sandpaper.

Then I glued the 45° side of the longer tube to one of the 45° sides of the short tube. You have to make sure that it fits well! I did the same with the other two tubes. It had to harden for a few hours!

Now I needed:

• fine marker
• Ø 1mm drill
• Ø 2.5mm drill
• piercer

For design reasons I decided to use a 5 thread tensegrity structure. One retaining thread and 4 threads for stabilisation. 3 threads for stabilisation would also have been enough, but I didn't think it was appropriate.

With the help of the drawing you can determine the points for the 4 holes for the nylon threads and the 2 points for the attachment to the tube. I placed one of the two rings on the drawing and marked the points with a fine felt pen at a height of 10mm on the ring.

First I drilled the 4 holes for the nylon threads with a Ø 1mm drill and then the two holes for the attachment to the tube with a Ø 2.5mm drill (8mm from the edges of the ring). I prepared the drill points with a piercer!

For this step I needed:

• fine marker
• Ø 2.5mm drill
• piercer
• 4 screws Ø m 2.4 x 12 mm and matching nuts
• pliers

First I marked the two holes at a distance of 8 and 22mm from the edge (at the highest point of the rounding!). Make sure that the angle pipe is absolutely vertical.

After I have drilled the holes I attached the ring to the tube with 2 screws Ø m 2.4 x 12 mm and matching nuts. Of course, you can also use a different screw size, but then you have to adjust the hole size accordingly.

I did the same with the 2nd ring and the angle pipe.

Now I needed:

• fine marker
• Ø 1mm drill
• piercer

In order for the tensegrity principle to work, the holes must be set as precisely as possible. This means that the suspension thread should later sit exactly in the centre of the rings. As the rings have a diameter of 110mm, the centre is at 55mm. Accordingly, the drilling points must be set at the lowest or highest of the pipe (see drawing).

For this step I needed:

• Nyon thread Ø 0.35mm
• Scissors

After I have drilled the holes, I attached the suspension thread. The distance between the upper edge of the top tube and the lower edge of the bottom tube should be 9-10 cm.

I took an approx. 25 cm long nylon thread and pulled it through the hole in the "lower" tube. I made a double knot on the outside. Then I pull the thread through the "upper" tube. Now it is important to set the knot so that the distance mentioned above is achieved. It does not always work right away! 

For the last step I needed:

• Nyon thread Ø 0.35mm
• Preserving jar rubberring
• Sewing needle
• Scissors

First I have cut 4 nylon threads about 40 cm long. I inserted them through the 4 holes in the ring and tied a double knot inside the ring.

A big problem with tensegrity projects is always the tensioning of the threads. Unfortunately, simply tying a knot at the right place does not work. That's why I was looking for a way to make it possible to align the threads. I cut 4 small pieces out of a rubber ring. These pieces are to serve as an "adjustment device".

I placed the top and bottom pieces so that I could pass the 4 threads through the "top" ring from the outside. I took the first thread, a sewing needle, inserted the thread through the eye and pierced one of the small rubber pieces from below, as shown in the pictures. To prevent the thread from slipping out too easily, I pierced the needle through the rubber again from above, not too close to the first stitch. Without thinking about the alignment at this moment, I did the same with the remaining 3 threads.

After all 4 threads had been prepared that way, I started aligning the threads. The small pieces of rubber can be moved. I started with it while the top and bottom were lying flat. When all 4 threads were almost evenly tightened, I have placed it upright and made the fine "tuning".

Done!

It is a fascinating experience when, after the assembly of the individual parts, this tension is suddenly created when setting up the object: TENSEGRITY!