Introduction: Connect PET Bottles, Make TrussFab Structures

Hi, this is guide for preparing bottle pairs for constructing TrussFab structures.

TrussFab is a plugin for SketchUp that allows you to fabricate large scale structures that are sturdy enough to carry human weight. TrussFab achieves the large scale by complementing 3D print with plastic bottles. TrussFab considers bottles not as “bricks”, but as beams that form structurally sound node link structures also known as trusses.

Find more about the project: https://hpi.de/en/baudisch/projects/trussfab.html

Here we describe three different techniques to form truss members from PET bottles:

1) Inflating (with dry ice or liquid nitrogen) - thanks PETMAT for the idea

2) screwing

3) taping

If you are interested in tryingout our TrussFab plugin for SketchUp (research prototype for non commercial use), just drop us an email!
contact author: robert.kovacs@hpi.de

You can also download our demo models from Thingiverse.

IMPORTANT: before you start your design, make sure that you have tested your bottles, adjusted the bottle lengths in the software to match the actual lengths, and test the print the connectors to see if everything fits well together.

Step 1: Connecting Bottles Using Dry Ice

Picture of Connecting Bottles Using Dry Ice

Take tree bottles of the same type, possibly with a long cylindrical bottom part.

Step 2:

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Cut one of them open and preserve the long cylindrical part. Make it as long as possible.

Step 3:

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Crease the other two bottles and insert them into the previously cut cylinder. Don't worry if they are getting crumpled, we will inflate them.

Step 4:

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Put a small spoon of dry ice into the bottles, close them and shake them until they blow up.

Take care: if you put too much dry ice, the bottle can explode. Make some experiments before you do this step. If the pressure is to high, open the lid for a second.

Alternatively you can also use liquid nitrogen for this step.

Step 5:

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If you choose the right type of bottles, they will fit inside so well that they won't come apart easily.

Maybe you'll need to try out different bottle types for this method. Also it might help if you place a bit of double-sticky tape on the inside of the cut cylinder. This will secure them even more.

Step 6: Connecting Using Wood Screw (you Can't Inflate)

Picture of Connecting Using Wood Screw (you Can't Inflate)

Alternatively you can choose this technique:

(1) You can use regular wood screws and an extra long screw driver. Drill small holes in the bottoms before screwing.

(2) Use dowel screws (double sided screw) and simply screw them into each other.

For this technique choose bottles which fit well together with their bottoms (they are not wobbling). Also try to use stiffer bottles, because you cant inflate these ones to increase stability.

Step 7: Use Any Kind of Wide Tape or Shrinking Tube

Picture of Use Any Kind of Wide Tape or Shrinking Tube

This method is probably less strong or long lasting, but very easy to do and you can achieve additional strength by inflating the bottles using dry ice.

For this technique choose bottles which fit well together with their bottoms (they are not wobbling).

Step 8: Now, Use TrussFab to Design Your Structure, Generate the 3D Printed Hubs and Build Your Thing:)

Step 9: Special Thanks to Everyone Who Contributed to This Project

Robert Kovacs, Anna Seufert, Ludwig Wall, Hsiang-Ting Chen, Florian Meinel, Willi Müller, Si-jing You, Maximilian Brehm, Jonathan Striebel, Yannis Kommana, Alexander Popiak, Thomas Bläsius, Tim Oesterreich, Dominik Meier, Melvin Witte, Tobias Arndt, Nico Ring, Lukas Fritsche, Thijs Roumen, Alexandra Ion, Oliver Schneider, Perdo Lopes, Mirela Alistar, Lung-Pan Cheng, Sebastian Marwecki, Arthur Silber, and Patrick Baudisch

Comments

vinstruct3 (author)2017-11-05

Where can the connectors be found?

vinstruct3 (author)vinstruct32017-11-05

Does this mean that if I can't 3D print or laser cut the key component I can't make these, i.e there are no commercially available connectors?

HCIHPI (author)vinstruct32017-11-09

You can also order the connector pieces form one of the online 3D printing services, like 3Dhubs.

MatiasG11 (author)vinstruct32017-11-06

Just ask anyone with printer for printing thith things for you.

HCIHPI (author)vinstruct32017-11-06

Hi, you can find some of our models here: https://www.thingiverse.com/HassoPlattnerInstitute...

but the idea is to generate them using our Sketchup plugin for your own structures.

best,

rob

rxxanne (author)vinstruct32017-11-05

The connectors are explained in the link near the start of the article.

ericCycles (author)2017-11-05

If you just need the liquid nitrogen/dry ice to reinflate the bottles so that they fill the sleeve, I would look a a bottle cap outfitted with a bicycle tire valve.

HCIHPI (author)ericCycles2017-11-07

Cool idea! How would you do it?

ericCycles (author)HCIHPI2017-11-07

You get a presta bike valve from an old bike tire,
drill a hold in a bottle cap for the bike valve,
insert the end of the bike through the hole,
add a nut and washers and teflon gas tape to either side.
Then attach your bike pump and pump away.

The air cannon/pop bottle rocket projects have lots of alternative designs for inflating a pop bottle using a bike pump.

HCIHPI (author)ericCycles2017-11-08

Yes, this would be super useful, but to do this for couple of hundreds of bottles is a bit tidies work... I have made an other type of bottle inflating device, which inflates them using a compressor and then tightens the cap. It works, but have to work on the usability a bit more. If you are interested write me an email and I can send you the files. Rob

padilla8888 (author)2017-11-05

How about the connection of the three or more bottles,joining the top of the bottles?

HCIHPI (author)padilla88882017-11-07

That is happening using the 3D printed hubs, generated by the trussFab software.

mrwonton (author)2017-11-06

AMAZING!

JamesA41 (author)2017-11-05

Awesome way to re-use waste where recycling isn't available or if user wants to. There used to be links online with someone, I want to say in Mexico since may relate to Mexico City once being a lake where floating gardens and waste merged into land covering the lake, making a houseboat also with yard area on top of bags/nets of plastic bottles. I've never seen anything like this. If you fill them with fluid you could store heat and also to equillibriate your environment slower. My Dad would do that with the hoop houses, green houses and in the basement.

Copymutt (author)2017-11-05

you lost me at "tack them" and then proceeded to inflate them.

Jim

sitearm (author)2017-11-05

No fair that boat oar should be made with trussfab too LOL. Nice work! : )

jw58479 (author)2017-11-05

Bravo guys !!! - Love your work. Its cool to see someone applying eng'g principles to an everyday common object that nobody even thinks about. Has anyone here made a storage shelf like this ? I'm going to start saving 2L bottles and see if I can get some of my boxes of stuff off of the floor. I'm also thinking about a double hull canoe/sailboat canoe, but that's a dream that's somewhere down the road, so I'll have to keep an eye on this ible. Keep it up guys, really outstanding.

ventifact (author)2017-11-05

You need a PFD and a longer paddle.

IndrajitA (author)2017-11-05

This is a fabuous idea. I am writing from Kolkata , India . Would like to work on this projectt professioanlly with TrussFab Structures. Please get in touch

multitechconsulting@gmail.com

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