multi-multi strand flexible small gauge cable

[olly_k]

Hi I am after some flexible instrument wire with an overall diameter of not more than 1.5mm. It must have many strands as it has to flex quite a bit.
Basically it is out of the end of the flexible hose of a Sebo vacuum cleaner. The flexible hose has a variable resistor in the end to control power levels and the housing can be turned something like 270 degrees. Instead of a contact system, wire is used in an ohm shape with guides. This is why the wire has to be flexible, so that it can handle the constant flexing involved. I have never seen wire as fine and with as many cores as the example I removed (silicon wire on ebay comes close but the smallest size is about 3mm diameter) and can't find any from my usual suppliers so help would be appreciated!
My only other option is to disable this feature, which I would rather not do!

 

[Sceadwian]

270 degrees over what arc size?
I'm not exactly sure what you mean when you say

Instead of a contact system, wire is used in an ohm shape with guides

 

[crutschow]

A search for small test lead wire (which is designed to be flexible) turned up this. It's 1.4mm in diameter.

 

[Sceadwian]

Only 7 strands though, but it depends on the actual arc of the bend and the number of repetitions as to what they'll need. For the price... You could make enough replacements for a lifetime even if it wasn't flexible enough to last a lifetime on it's own.

 

[olly_k]

270 degrees over what arc size?
I'm not exactly sure what you mean when you say

Instead of a contact system, wire is used in an ohm shape with guides

Yes ok you can imagine that a contact and ring system would normally be used where there is rotation involving a pipe carrying an electrical conductor, especially if full rotation is required! well indeed such a system is used at the vacuum end. At the 'sucking' end, the wire comes out of the flexible tube, and each wire wraps just less than 180 degrees around the tube fitting in opposite directions. As this fitting is rotated when in use, one end of the wire is able to wrap itself round while the other end unwraps itself. when centrally fixed I would say the wires kind of take on the shape of an Omega sign, although maybe the little feet are distorted . Oh the arc size is a standard vacuum tube say 1 1/2"???
@Sceandwian thanks for the suggestion the original wire has far more strands than your example. I actually tried standard stranded wire and it failed after a while. I think the original stuff must have at least 25 strands but memory suggests many more!
I would disable this feature (there is a microswitch that shorts the wires to the motor control pcb when the tube is removed at vacuum end so accessories and other tubes can be used) but as there is no mechanical suction control it would make releasing non intentionally sucked items a pain!

 

[crutschow]

It has only 7 strands but 7 strands in a 24AWG cable means that each strand is only about 32AWG and wire that small is pretty flexible.

 

[Sceadwian]

Flexibility isn't the issue though it's repeat flexing. Copper wire will work harden with repeat flexing and break regardless of how fine it is, so the material is critical, whatever the alloy it is it has to be designed to avoid work hardening. The only tip I can give is that what you want is elasticity not plasticity. Common copper conductive wire is a very plastic material but work hardens because of it's nearly pure crystalline structure, you need something that will give again and again because of it's structure, it's going to be an alloy of some kind.

 

[KeepItSimpleStupid]

These guys: Gotham Audio LLC ~ The exclusive American and Canadian importer for Gotham Audio Cables have some nice stuff. Also search on LITZ wire.

 

[Sceadwian]

Litz wire is just fine enameled multi strand wire, the poster doesn't need the individual strands insulated for his application it will just increase wire diameter, and it's still made from pure copper which means it will still work harden and fail with repeat flexing.

 

[KeepItSimpleStupid]

I'm not sure what he wants. I do know I had to replace pop up headlight wire with test probe wire because of the flexing.

 

[dougy83]

The wires in the old telephone curly cords were very resilient to bending & flexing. They were sometimes made using a spiral of copper/aluminium foil and cotton thread; sometimes just copper & thread strands (which also reduced stretching of the copper strands). The same sort of wire was also in some old CB radio curly cords.

Don't know if you can find it that easily these days, but maybe worth a look.

 

[Sceadwian]

Headlights are a few cycles per day, a vacuum cleaner hose during normal use is a cycle every few seconds.

 

[jpanhalt]

That ultra-flexible wire is used often in model aircraft. I use it when I need to pull long servo leads through thin wings. If you search on "noodle wire" you will find many hits, mostly to the larger gauges used for motors and such. That wire is usually silicone insulated.

However, PVC insulated wire in quite fine gauges is also made and used widely for servo hook-ups and micro-flyer antennas. Daburn (https://www.daburn.com/2671UltraFlexibleSub-MiniatureWire-U/LSTYLE15681692.aspx) is one manufacturer. For use with servos, as mentioned above, I use the 22 or 24 AWG with PVC insulation. I also have some very fine stuff for connecting sensors.

The problem is purchasing minimal quantities. Many of the hobby suppliers in the US sell it in small amounts or even by the foot.

John

 

[nsaspook]

I've used this cable on machines that require constant movement. Never had a failure due to the wire.
https://www.electro-tech-online.com/custompdfs/2011/05/NP218.pdf