Curly Cord

I am looking for a decent length multi conductor curly cord. So far the
most I have found is 10 conductors. Its for a custom built remote for a CNC
machine, but if anybody knows wire its this group.

I can get by with 10, but 12 would be better allowing my to run a separate
common for critical items like an emergency stop circuit. I'ld like
conductors large enough to tin and put in a screw terminal, and a fair
amount of straight jacket at each end. If the curly part easily stretches
to about 4 feet with a max of 5 or so it would be perfect.

 

check with Stanton industrial electric supply he finds all kinds of wire for me412-242-9300

 

If you can't find it, I believe it's possible to construct your own
using highly flexible wires and curly plastic tubing. Assuming you
have room for that. At least that way, you shouldn't run out of
conductors. As I recall, something like 4 inch diameter plastic
coils.

One project we used fibred flex cable all rolled up. take a look
inside an old printer for an example. Interestingly, the strain relief
had to extend several inches because even the longitudinal flexing of
the cabling tended to break it. Another polyimide PCB [I think, may
have been polyamide, which works in a vacuum, too]

From memory, the high quality curly cords we used were copper foil
wrapped over silk thread. They were rather resistive, but never broke,
and IMPOSSIBLE to kluge to to make a temporary connection. The cheap
ones out of Asia were simply tiny fibres of copper, like 15-22 strands
per conductor, but they were one tenth the resistance and EASY to
kluge connections to with a soldering iron, which is guarranteed to
make a spot for the cable to break.

 

Typically with a curly cord there is a fixed cable pass through were
movement ends if setup properly. There should be a strain relief installed
at that point also. All splices, connections, etc should be made beyond
that point so that no movement can dislodge them or create high strain at a
"hard point" like the tinned end of a conductor. Even something as simple
as the plug on the end of a telephone cord employs this principal to some
degree. There is a plastic tab that compresses down and holds the cable in
place. The individual conductors are then penetrated (for stranded) or
skinned (for solid) beyond that point to make the electrical connection.

 

I know that nowdays you can buy just about anything that you can think of but years and years ago when I was working for a manufacturer we needed a coil cord (only one for a custom made one of a kind product) I was shop forman at the time so I had the responsibility of getting the end product made.

I found a coiled spring about 18 or 16 ( forget) guage spring steel, about 2 inches in diameter and one foot long retracted. I located some of the type of wire they use in telephone coil cords. ( woven with thread ) but it was 22 guage wire. I threaded some thin teflon tubing over the spring (to avoid abrasion) . I had discovered somewhere that if you soak vinyl tubing inMethyl Ethel Keytone that it will expand and when it dries out, the tubingwill recover to it's original diameter. I picked a size of thin wall tubing that wouldn't be too thight and pulled the teflon covered spring and the 12 strands of wire through the expanded PVC and let it dry in the coiled position. I wound up with a fairly tight 3 foot (retracted) coil cord that was being used daily maybe five hundred to a thousand expansions a day. As far as I know, the system was still functioning 5 years later. It was only being pulled out to about 4 to five feet, so it didn't get that much wear. The hardest thing in the whole project was terminating that damn wire. I doesn't solder or crimp easily.

 

Yeah... termination is a pain. Had to do that once or twice for custom installation. I'm actually considering using one of the 10 conductor prefab RJ45 style plug/cords instead, and moving my E-stop button to a fixed location instead of on the control pendant.