# Simple Tensegrity Set

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## Introduction: Simple Tensegrity Set

This is my entry into the Chopstick Challenge.

Give credit where credit is due:
When I first started thinking about this challenge my first idea was to construct a tensegrity tower using chopsticks.   I did a quick google search and wouldn't you know....there was a instructable which did it better than anything I could do..
https://www.instructables.com/id/Desktop-Tensegrity-Tower/

As an architect I've always been fascinated with tensegrity.  Tensegrity is a way of constructing using rods & wires.   Structurally it's brilliant.  the components are in pure tension and pure compression.
so for my entry what I thought I'd do is to create a construction set to teach my kids about tensegrity.  by creating a kit of parts, kids can create an infinite variety of structures.  the set can also be expanded with additional pieces and pieces of a variety of lengths.  just because of the time constraints I'm gonna stick with a single length rod and build a simple structure.

CHEATER CHEATER PUMPKIN EATER......
I only had a couple hours to throw this together, and unfortunately I couldn't find chopsticks so I'm using 3/16" dowels.    I think these have the same properties as chopsticks so I hope you'll forgive my substitution.   I promise that when time allows I'll update the ibby with chopsticks.

SUPPLIES:
Chopsticks - the more the merrier.  a minumum of a dozen.
rubber bands
electrical tape

TOOLS NEEDED:
utility knife
hand saw
cutting mat
spray paint  (if desired)
drill (if you need to drill out beads)

If you wanna see some models that are truelly amazing and much better than this check out:
http://you-can-touch-this.blogspot.com

### Teacher Notes

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## Step 1: Cut Chopsticks Down to 6" Lengths

the first step is to trim down your chop sticks.   I do not have very big rubber bands so I'm going to keep the sticks 6" long.

After I had all my sticks cut down the next thing I did was to throw on some quick color.   I was really pressed for time so I just laid the sticks on paint table and hit with paint.   after waiting 15 minutes I rolled the sicks over and hit the other side.

## Step 2: Use Utility Knife to Cut Slits in Sticks

once you have all your sticks cut & painted to your licking the net step is to cut slits into the ends of each stick.

using a cutting mat and a sharp utility knife cut 1/2" slits into each stick.  when you cut the opposite end take care to align the cuts.   it probably doesn't matter but I think it looks better.  don't worry if the stick splits and your cut is longer than 1/2".

BE CAREFUL TO NOT CUT TOWARDS YOUR FINGERS!!!!!!   when you hold the stick hold it above where your cutting.  stick in the utility knife in at the slit end and pull towards the end of the stick away from where your holding the stick.   as a kid I cut my finger once and had to get stich's.  I was cutting towards my hand.  the blade got stuck a little bit, I naturally pulled harder, then it gave and blade jumped and cut my finger.  so always cut AWAY from your hand so that if the blade jumps you won't get cut.

once all the slits are cut, then take 2" strips of electrical tape and wrap it tightly around the ends of each stick just below the slit.  this will keep the stick from splitting once you it gets the tension of the rubber bands.

ok,,,,, since I'm cheating and using dowels i got lucky with my beads.    I found wooden beads that had a hole that fit perfectly on the ends of the sticks.

if you cant find this then you'll need to drill out the beads to fit the sticks.  since chopsticks taper you'll have to drill different size holes for each end.   I recommend find 2 different shaped beads (circles & squares).  then drill one kind of bead to fit one end and the otehr kind of bead to fit the other.

use pliers to hold the beads while your drilling so that if the drill skips it wont get your hand.   take your time so you don't split the bead.

## Step 4: And Now...Start Simple

ok....I'm gonna start with a simple structure.  at some future point I'll update this with some more complicated structures.

start with 6 sticks.   if you have painted them different colors then pick 3 pairs of 2.
arrange sticks into "star" pattern and hold together with a rubber band as shown in photo.

now that you have the "star".  you'll need 6 rubber bands.  be careful that the rubber bands are all the same size.  if you use different size rubber bands they will pull differently and you'r final shape will be unbalanced.

take each rubber band and stretch it end to end on each stick so that it runs in between the crossing pair or sticks.  be careful to stretch the rubber band evenly so that the rubber band is in even tension on each side.   repeat this for all 6 sticks.   if the slits of the sticks looks like it might split you can put a wood bead on the ends to hold is together.

## Step 5: Tie the Sticks Together

Now that you have the star shape with rubber bands streched from end to end on each stick it's time to tie it all together.
at the center of each rubber band where it goes between the crossing stick, strech it up to the end of the crossing stick.
once you've connected it to the crossing stick, put a wooden bead end cap on to keep the tension from breaking the end off the stick.

repeat this for all the rubber bands.

## Step 6: And Now It's Time to Cut the Chord.....

and now it's time for the big reveal.  simply take some scissors (or utility knife) and cut the center rubber band which is holding all the sticks together.   you're model will now spring to life.   if you've been careful and your rubber bands all have balanced tension then your model will be balanced.  if it's uneven then simply go around and find where the rubber bands have uneven tension.  remove the rubber band from the end and then replace trying to have even tension.    DON'T TRY TO PULL ON THE RUBBER BANDS TO ADJUST THE TENSION.  THE RUBBER BAND WILL BREAK (I LEARNED THAT THE HARD WAY).  with a little adjustment, and a little patience, your model will be balanced.

YEAH....IT WORKED!!!!!

so that's it there's my chopstick model.....kind of.
I've seen this done with soda straws so I'm fairly confident that it will work with real chopsticks.

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## 10 Discussions

I have wanted to play around with making tensegrity models for a while now- thanks for the inspiration!

Always a pleasure to see people getting into the game of building tensegrity structures. As I made quite some myself (have a look at http://you-can-touch-this.blogspot.com if you fancy), there's one thing I'd like too mention.

Rubber band is fine for prototyping, but won't last very long. In a couple of weeks your tensegrity icosahedron will start disintegrating, which is quite a shame if you went through the effort of painting your struts. If you get yourself some elastic jewellery cord (minimum 0.5mm diameter, up to 1mm diameter works fine), you have the same behaviour for much longer. Just cut the cord into pieces of 13-14'', tie them into a loop, your model will last for years.

wow, your structures are really amazing. my stuff is pathetic compaired to yours.
I'm gonna have to look into jewelry cord. I think that will work mcuh better than the rubber bands
thank you for the suggestion.

maybe you can help me. In my instructable i show a simple 6 rod model. I've been trying to remember how to create a 12 rod model but i can't get it. I was going to add that to my instructable but it's kind of hard since I can't figure it out myself.
any thoughts?
here's what I'm trying to do:

The structure looks like an octahedron to me - I posted a how to on my website for this: http://you-can-touch-this.blogspot.com/2011/04/how-to-build-octahedron-with-affordable.html

The basic build method incorporates having a groove to slot the elastic in (not a loop this time, just an elastic connected to both ends of a strut). The beauty of this method is to use identical elements along the way, and building symmetrical structures with at least 12 struts is much easier than a minimal tensegrity (3 struts, 9 tendons) or a 6 strut tensegrity like you did here.

I got my elastic cord via ebay, there;s plenty of suppliers that sell smaller amounts (5m to 10 m), and even 500m spools. The tensegrity towers need some bit of fiddling, the more struts comprise a single shape, the easier the build will get.

I haven't gone through all the all how-to for bigger structures, but if you want to have a toolkit (or rebuild your own), check out http://youcantouchthis.bigcartel.com/ , I got a toolkit that can build all platonic solids and more available (just without decent instructions yet).

Tensegrity rocks, and can inspire a lot of architectural challenges. Thanks for sharing, enjoy exploring more of it.

thanks
I'm gonna try to build this later tonight and hopefully add it to this.
I've added a link to your site in my instructable. i'm just the beginner trying to play Mary Had A Little Lamb where your stuff is like Beathoven. gotta give credit to the masters.

I'll look into your kits. Years ago I had a kit called "tensegritoy" and that was the idea behind my instructable. i used to be able to build all kinds of stuff but can't remember anything now. i thought it would be like riding a bike and it would all come back to me but i don't seem to be as bright as i used to be......

:)

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собрана коллекция на разные темы обоев для стола, только здесь обои без регистрации зайди и скачай качественные обои за два клика.

Nice job, sir. Good luck in the challenge.

Cool!
At first I thought you'd done this by sticking chopsticks in olives, which would have been most excellent. ;)

ok......I have no response to that......but ......uhhh.......thanks
:)

I'm gonna stop by a couple Chinese restaurants on my way home tonight and get a hold of some actuall chopsticks. hopefully I can update this by the 7th.