Throughout most of my life I have been a scavenger. My eye is always peeled and on the lookout for that little bit of technology that I might be able to use someday. As a boy one of my favorite things to do was to walk along the curbs in the small city where I lived and pick up the small screws and bits of metal that I might find there. This tendency to be on the lookout for materials that just might be needed someday continues even to today. I want to tell you about one item that I found that has proven very useful in many applications and which you can probably find for little or nothing in your own local areas.
A while back I discovered a source for some very special wire. While I am sure it must be available in large spools commercially I have never found anyone anywhere selling this wire at the retail level. This wire is about 1.1 mm in diameter and contains 105 solid strands of copper each with a diameter of 0.0635 mm. I have found it in the colors of Red, Black, and White. I have tested the resistance of a piece of this wire and found it to be 0.084 ohms per meter. As you can imagine, with 105 strands of wire with a diameter of .0635 mm, which is approximately the diameter of human hair, it is very flexible and more importantly practically unbreakable with repeated bending or twisting. Here is a picture of a sample of the wire and what the stranding looks like.
If you use the standard bread board jumper wires at your bench for comparison, they have a diameter of 1.37 mm and contains 12 strands that are solid copper with diameters of 0.1 mm. This means that the copper cross section area of a bread board jumper is about 0.094 mm squared. The copper cross section of the special wire even though it has smaller strands is 3.5 times as great as the bread board wires at 0.33 mm squared. Here is a picture of standard bread board jumper wire.
The source of this wire is from the dental industry. There are a couple of devices commonly used in the dental clinics of the world that have these wires in a cord that runs from a control box to an instrument held by the dentist. These cords are special medical equipment and as such they commonly sell for $300 dollars and up. One is called a Power Optic Handpiece Hose. Do not confuse this Power Optic Handpiece hose with a similar hose called a Fiber Optic Handpiece Hose. With one you get the cool wires and with the other you get glass fiber optics. In both cases the purpose is to get light to the end of the drill used by the dentist to cut tooth material. There is also another instrument that is common in the dental clinic called a Cavitron or a Scaler. This instrument also has a control unit and a wire cord running to an instrument in the dentists hand. Here again the cord is very expensive and uses the cool wires that I have described to bring power to the handpiece. In this case you are looking for a Cavitron or Scaler handpiece cord.
While the wires themselves are flexibly almost indestructible the cords themselves do fail for a variety of other reasons. At this point the cord is worthless to the dentist or the person in charge of replacing it. This is where you come in and rescue that cord and its cool wire from the scrap heap.
You could start by asking a dentist where he gets his equipment repaired. The company or person that does his repairs is quite likely to have a pile of these failed cords and if they don't you can ask them to start saving them for you. Each cord should yield 4 to 8 meters of wire depending on the length of the cord and the type of unit it was made for.
I like to use these wires for applications where there is flexing and vibration. Their ability to carry 1 to 2 amps continuous duty also makes them ideal for special applications where both power transfer and flexibility is important. These are strictly low voltage wires however and should not be used above 30 or 40 volts.
Happy Hunting
John
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