I really heart coiled cords. I think coiling is a very elegant way of dealing with the problem of unsightly slack cables, and often I find myself wishing that this or that appliance had come with a coiled cord. Replacement cords that are factory-coiled can usually be purchased and installed (if necessary), but that may be an unnecessary expense because, with some simple tools, it is easy to coil a straight cord yourself.
- Pipe or other metal mandrel
- Heat gun
- Sink with sprayer (or other source of cooling water)
- Duct tape
- Aluminum foil
- Cord to be curled
Step 1: Wrap the cord around the mandrel
Find a metal round, the outer diameter of which is equal to the internal diameter of the coil you want to set. Duct-tape one end of the cord to one end of the mandrel, as shown, and then wind the cord itself tightly around the mandrel until all the slack is taken up. Then duct-tape the other end of the cord. Make sure to use plenty of tape so the coil doesn’t come loose with handling.
Step 2: Protect the ends of the cord with foil
If your cord has a connector at either end, you have to be careful not to melt, warp, or otherwise damage it in the process of setting the coil. So cover the taped ends of the cord with aluminum foil, reflective side out. This will help to reflect heat from the heat gun away from those places you don’t want it to go.
Step 3: Apply heat to the cord
My workshop sink proved to be a convenient place to heat the cord. I set the mandrel across the sink, as shown, and rolled it back and forth with my left hand (to distribute the heat evenly) while waving the heat gun with my right. If you don’t have a sink or your coil is too long for one, you may have to improvise some other arrangement for rotating the mandrel while simultaneously applying heat.
Step 4: Quench the hot cord
Apply heat gradually, over the course of about ten minutes, until the plastic insulation just begins to smoke. Then immediately remove the heat and quench the hot cord with cold water. Continue cooling until the cord is barely warm to the touch. Remove the cord from the mandrel and blow-dry it completely with the heat gun on a low setting.
Step 5: Test the cord before use
Do not attempt to use the coiled cord until you have verified with a multimeter that it is not shorted or otherwise damaged. Using the continuity/ohmmeter setting, apply the probes to corresponding leads or contacts at each end of the cord. The circuit should close for corresponding leads, but should open when you move one probe to the other lead.
Notes and ideas
Be sure to work in a ventilated area. If you do this correctly, the plastic will smoke only for a moment, but it’s good form to avoid exposing yourself to that smoke in any case.
Instead of rotating the pipe as you apply heat, it might be possible to direct the air from the heat gun down the length of the mandrel (assuming it’s hollow) from one end, perhaps using a metal funnel to help channel the hot air. This operation should heat the circumference of the pipe, and thus the cord, more-or-less-evenly.
If the tape leaves behind residue on the cord, use a paper towel moistened with a dab of acetone to remove it.
Finally, I should point out that I have only attempted this operation on the guitar cord shown, which I think is insulated with PVC. It the insulation of your cord is some other type of plastic, it may or may not work for you. If anyone knows anything about plastics commonly used to insulate appliance and audio cords, please feel free to enlighten us in the comments.
Update: Timothy Silverman sent in this photo showing a cross-section of a factory-coiled cord. Note the “filler” between the wires and the sheath–it’s this material that supports the factory cord’s tighter coil. My cord has never been as “tight” as a cord with an original coil, but I’ve been using it weekly now for almost 8 months and it has not slackened appreciably.
28 thoughts on “Make: Projects – Cord curling”
I wanted the connector at the end of a curly cord, so I cut it off. I found that most of the cable’s cross-sectional area was occupied by solid plastic of some flexible type. The curl in my specimen was mostly held by this plastic and not by the outer insulation. So if your homemade curly cords are less curly than commercial ones or if they eventually relax and lose their curl, it might be because instrument cables lack this special interstitial curling polymer.
That’s good intel, TY. Next time I have a scrap coiled cable I’ll repeat your experiment and see what’s within and report it here. It’s true that my cord is not as springy as a factory-coiled cable, but so far it has held the coil I set quite well. Only time will tell, however. Hopefully I’ll have the presence of mind to revisit this page in a year or so and report how it’s worked out. :)
I have quite a few coiled cables, including Sony MDR7506 headphones with a PVC cable jacket, and a Canford coiled balanced audio XLR cable (which I use for interviews with a hand-held mic). The latter is with a polyurethane jacket. It is about the same dimensions in cable width and coil size, though the latter is slightly heavier. More importantly for some applications (and to my liking), it has a much greater spring to it. Under its own weight, the coiled length of about 1m hardly elongates at all, whereas the headphone cable does.
Less objectively, it feels more hard-wearing. Canford claim the urethane, the only material they use for their coiled cables, retains the ability to spring back into shape after long periods of time spent stretched out, whereas PVC will permanently elongate.
I guess you could fix that with the technique above, though?
And there’s the expert I was hoping to hear from! Thank you very much for taking the time. Can you tell us, is there any difference in the appearance of the PVC and urethane cables? Would there be any easy way to tell them apart if you didn’t have manufacturer’s info?
It remains to be seen whether my freshly coiled guitar cord will lose its “permanent wave” with time, and to what extent. At one week in I don’t see any change, but that’s hardly telling. Even fresh off the mandrel, however, there’s no doubt that the cord is not as “springy” as some coiled cords I’ve seen. It will elongate under its own weight, and I’m not sure there’s any way to get it to coil more tightly. So I’m doubtful that this process could be used to tighten the coil of a factory cord that’s slacked up.
You want to be especially careful to work in a well-ventilated area if you’re applying heat to PVC – not only will exposure to the fumes heighten your risk of pancreas cancer in the long run, but the melting PVC releases hydrochloric gas, which can cause eye and lung damage in the short-term.
Coiled cables add capacitance and inductance to the signal, so they tend to suck high end out of the tone. If you notice your tone sucks, switch to a straight cable to see if there’s a difference.
think this’d work with a bike cable or would it have to be a product of the steel braiding? a lot more strength in the wires obviously so probably the plastic wouldn’t cut it.
Yeah, I’d be surprised if that worked. But ya never know until ya try…
I don’t think I would recommend this for anything but novelty purposes. While it’s certainly interesting, it will most likely introduce trauma to the shielding and reduce its effectiveness. As another reader mentioned, there are inductance issues as well.
That said, I’m amazed that most people don’t know how to properly wrap a cable, and it may be that the desirability of a coiled cable is because of this. A properly wrapped cable follows the lay of the shield and can be thrown out into a perfectly straight and relaxed line with no twisting or curvature at all. This is far better than compensating with a coil. No doubt there are instructions online for how to do this and with a bit of practice it can be done quickly with a “well trained” cable.
I probably should’ve known better than to demonstrate this technique with an audio cable; it’s simply what was convenient to hand. More often than not, it’s appliance power cords that I find myself wanting coiled, and the reasons are largely aesthetic, and partly to do with convenience, in dealing with slack cords all over my living room or office. I certainly did not want to end up arguing with audiophiles about signal degradation, which is, frankly, a bottomless pit.
Even so, I have to say I find your claims about “trauma” to the shielding a bit vague. Assuming the shielding in question is metallic, it’s hard to see how it would be damaged in the slightest by this treatment, which introduces no sharp bends and does not even momentarily approach the temperatures required to begin annealing copper, aluminum, or any other metal which might reasonable be chosen to shield a cable.
Sheilding used in many cables (except extremely expensive audio/video cables) is often little more than a 30% braid, and a foil wrapper. You will find that the foil will melt at a lower temp, like a heat gun. I have learned this from many hours of working with high quality cables with similar foil sheilds – if the soldering iron gets too close to the foil it’ll melt, and it will also cause the other conductors to melt, shorting them out.
I like the job you did on this cable. The only cable I would not do this too at all would be RF – If you’re going to coil them, simply cable tie them in the loops, because once you damage an RF cable, you might as well just throw it out, it’s a pain to fix them.
Thanks for this post! It is exactly what I needed for a DIY project. I have a quick question that someone with materials knowledge might be able to answer. If the straight cable that I would like to coil is made out of a thermoplastic elastomer and I overmold it with silicone and attempt this process, will the cable coil? I know that silicone will not, but will the material INSIDE the silicone coil and force the silicone to take its shape?
Sounds complicated but I’m hoping someone out there is knowledgeable in this topic. Any input or info is greatly appreciated. Also, do you know up to what temperature does your heat gun go to?
In answer to your first question, I think that would probably depend on the thicknesses of the thermoplastic and the silicone, respectively. Most coiled cables actually have an interior curling element of some sort and don’t just depend on the plastic sheath to hold the coil, so I would guess that a cable without the interior support, and with a non-coiling silicone outer layer, would not hold a coil very well. Again, however, there are a lot of variables and you won’t know for sure how well it works until you try it. Experiment!
My heat gun is marked up to 1000F, which is the setting I had it on. Who knows if that number has any bearing on the real temperature of any part of the system! That’s why I use the empirical test “heat the cord until it just starts to smoke” instead of specifying an exact temperature.
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