Heat shrink Cordage from Plastic Bottles

Overview: Plastic Bottles can be ‘spiralised ‘ in that a length of cordage can be cut using a knife blade on a jig Note: There is a significant risk of being cut by the blade if it is not installed safely! This cordage is very strong and can be made even stronger by weaving several lengths together.  It also has ‘heat shrink’ properties – When heated it shrinks so it can be used for covering items, binding etc

A wooden block has a knife blade mounted between two stacks of large washers – see the diagram. Note ensure it is tightly held and the edges of the blade do no protrude beyond the washers. A gap of about 3-5 mm between the washers is where the cutting blade operates – this gap should be too small for fingers to be cut. The bottom of the bottle is cut off and the bottle placed so that the knife blade can cut a strip off when the bottle is rotated. By rotating the bottle and pulling the strip the whole bottle can be turned into cordage.

Equipment Provided: Plastic bottles, wooden blocks, craft knife blades, large washers, screws, screwdriver, scissors

Health and Safety: You must carry out your own risk assessment (Rubbish Science accept no liability)  Note: Be careful when cutting.  Adult supervision required at all times 

Things you might need to know / Questions you might ask:

  • What is the best thickness of the plastic strip? (You can change this by mounting the blade higher or lower on the washers.
  • What size bottles work best?
  • Should you use one or more LEDs?
  • Should your LEDs be wired in series or parallel?  (Parallel will be brighter, but wont be lit for as long)
  • How can you weatherproof your bottles?
  • Can you combine this system with the Bottle of Light (Litre of Light?)

Prototyping: Try to answer the questions above using small scale experiments

Modifications:How might you modify your designs based on what your preliminary results look like? What have others done and what can you learn from them?

Prediction: What do you think will happen and why?

Do it: How are you going to see if your light is successful?

What happened?: Was your light effective?

Tell Someone: Explain what you did and why you felt your LED was effective. Listen to others, do they have any good ideas?

What did you learn? What do you know now that you didn’t know before you started this investigation?

Extension/Modify/Do it again: How could you extend this to produce a commercial LED installation business?