wiring ptfe where to buy

[Dylwad]

2 hours ago, chrisalbertson said:

"ultra flexible" 20 gauge wire would have 100 strands, where each is 0.08mm in diameter.  The stands would not be twisted like that as the standes need to move relative to each other when the wire flexes.    The wire in the photo is a good and tough wire that would work very well in a vehicle's wire harness.   That is its intended use too.

If you need continuous flex, like for use on a cable chain, you are likely better off with (1) Silicon, ultra flex and (2) going with a larger cable chain. 

Or if you have the budget Igus warranties their "chainflex' cable for four years and claims 4 billion flex cycle lifetime.

For some reason this cominity of Voron owner seem to concentrate more on the insolation type than on the conductor.  In other places people think more about the metal inside.    I think this might be because the Voron cable chains are undersized.  Maybe.   

That goes against motorsport wiring conventions, the strands in the wire are twisted, and the bundles of wire get concentrically twisted together for a super flexible cable that when flexed and bent in a harness the twist of both prevents strain and buckling in the wire strands. Granted this is for a non motion application but the harnesses are subjected to big temperature swings, a ton of vibration, and frequent removal/install. 

My last harness was 48 wires, with a core of 3x 3 conductor shielded, ranging from 20-16 gauge and it was flexible like a wet noodle after recovering the shrink tubing on it. Running the same harness not twisted ends up rigid. 

[chrisalbertson]

9 hours ago, Dylwad said:

That goes against motorsport wiring conventions, the strands in the wire are twisted, and the bundles of wire get concentrically twisted together for a super flexible cable

I have to agree about twisting now.

The key is the amount of twist.    

The reason you need it is that when you bend a wire the strands on the outside of the bend take a longer path and get stretched and the inner strands take s shorter path and get compressed.  Metal is not good at stretching or compressing so it is hard to bend and not flexible.

But if you twist the wire, each strand is alternately on the outside and then the inside of the bend, so it is being alternately stretched and compressed.  If the strands slide just a little then can lets the stretching and compressing even out

But if the strands are twisted tightly and bound strongly to a hard plastic insolation, they can't move relative to each other.  I'm looking at the design of the best flexible cable.  It is made by Igus.  I notice they use a slight or loose twist and importantly they include a slippery kind of plastic fiber between the conductors

Then from an interest of mine, I was studying microphone cables.  Sometimes these need to be flexible if a mic is handheld but flexing causes the wires to move relative to each other and this movement creates static electricity that you can actually hear in the recording.   The effect is real, you can measure it.   But I think in our cases this is not important.  It would affect the thermister reading but the effect is small and random and would average out over time.

Finally, there is a calculator on the Igus website that lets you put in things like the weight of the cable and the speed and acceleration and the radius of the bend.  Then it suggests products that will work.   I think if performance were more important than money, the best solution would be to go to Igus and buy whatever they suggest.   They actually offer a warranty against damage by flexing and claim 4 billion flex cycles.  (Some quick math says that the cable chain on the X or Y axis, 4B cycles is years 80 years of 24x7 printing).  If money is an issue, go there, see what they suggest, then try and make your system close to the suggestion.