Wire Wrappers

by Bert Van Kets

One of the smaller problems you face when building a model helicopter is fixing the wires that run from the battery, gyro or servo to the receiver in a clean way, but still easily detachable. You could use wire straps or tape, but that is more a permanent solution. Wrapping them around a pencil so that they form a helix is also done a lot, but they still are hanging around freely, ready to be caught on something.

Using a helix made out of thin plastic is perfect for our purposes. It's easy to apply, easy to detach and very cheap. Commercially available helix wire wrappers are too big and too heavy. Let's create our own at a fraction of the cost.

PET Soda Bottle

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PET is short for Polyethylene Terephthalate and is a kind of polyester plastic. As it's a thermoplast it can be shaped using heat. Get a PET soda bottle out of the recycle bin and cut the top and bottom from it. Slice it open lengthwise so that you get a flat piece of thin plastic. Use your steel rule to cut a strip of about 3mm wide.
  

Wrap around a stick

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First of all you need to get two pieces of tape ready. Then stick the piece of plastic to the top of the tape at a 45 degree angle. Check the second picture below. Wrap the tape around a stick. The diameter of the stick will define the diameter of the wire wrapper. Wrap the piece of plastic around the stick, maintaining a 45 degree angle. The sides do not have to meet. Leave a gap about the same width of the strip. When the whole strip is wrapped around the stick, fasten it with the second piece of tape.
 
 

Heat up

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Get out a torch of some kind. I use a pen torch as it is just the right size. Don't use a candle. This leaves too much soot and does not disperse the heat enough. You have to go rather close to get the plastic to set and you risk melting it entirely. The trick is to apply just enough heat and never too much. An alternative I haven't tried is a heat gun used for removing paint. It should work nicely.
The aim is to heat up the plastic to that it gets above its plastisizing point of around 120 degrees Celcius. If you heat above 160 degrees Celcius, its melting point, you'll be left with a very thin strand of formless plastic that is useless. Be careful with the heat. Little bits at a time and certainly never too much.
It's very easy to know if you have applied enough as the edges of the plastic will start to curl up. Don't heat any more as you are already around the melting point. A little practice makes perfect.
 

Finishing

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Remove the tape and slide the stick out of the helix. Test the spinginess of the wirewrapper. You'll be amazed at how far you can unwrap it, while it still returns to it's new shape.
Cut off the edges that were covered by the tape and thus not set. Admire your work and try it on your helicopter.



Use the wire wrapper to fasten the antenna to a skid.