Radio Dial Cord

[Audiorepair]

Radio Dial Cord, the (usually) white cord that wraps around pulleys, tuning controls etc, and seems to be good at not stretching over many years' use.

I see plenty of NOS and new out there, but does anyone know what is the best stuff to go for, or what to avoid?

In my case it is actually for a motorised fader, but the principle is the same - cord wrapped around grooved slotted shafts and a couple of pulleys, tension quite high, lots of use over many years.

The motorised fader system replaces the tuning capacitor with a motor, so what was the moving tuning indicator becomes the fader.

[richnormand]

https://www.amazon.ca/Dial-6138-Vintage-Radio-Cord/dp/B004IAKWLU

[bob91343]

I have always been successful with ordinary fish line.

[Audiorepair]

I have always been successful with ordinary fish line.

Interesting you mention that, as I was looking at Kevlar today, as it is very strong and doesn't stretch.   
I think 2% stretch before breaking.
It is typically used in fishing line and kite flying cord.

https://www.ebay.co.uk/itm/KEVLAR-DuPont-RAW-YELLOW-100-LB-0-5mm-200FT-61-M-LINE-BRAIDED-WIRE-KITE-FISHING-/282055551022

I'm hoping to replace the cord on motorised faders, though I'm not sure exactly what they have used.
The frayed ends are nylonish in appearance, so I took a guess that it would be Radio Dial Cord, and ordered some of this to see if it looks and feels the same. 
Dacron I found is a polyester, don't know if that looks "nylonny" or not, but will soon find out.

https://www.ebay.co.uk/itm/Radio-Dial-Cord-2m-Length-x-0-5mm-Dia-NOS-Vintage-Dacron-Valve-Transistor/254754388794?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

[james_s]

I usually get that sort of thing from justradios.com, they've never let me down.

[WattsThat]

Any fishing braid will be low to zero stretch, it’s why it is used.

Here’s a lifetime supply of dial cord for $4 with free shipping. Select the 90lb rating and you have your choice of colors!

https://www.amazon.com/Ashconfish-6LB-Abrasion-Resistant-Incredible-Superline-Zero-Stretch-Superfine/dp/B07J9YMW4F/ref=pd_di_sccai_5

[bob91343]

I didn't see anything for only $4 and as usual, Amazon is overpriced.  As I recall, the stuff to use is around 30 lb but my memory on that is hazy.  Stretching isn't usually a problem, since there are springs there anyway to keep the string taut.

[WattsThat]

Okay it’s a Prime deal at $4, a whopping $7 for non-Prime. Any of the current braids at 30lb are about .01in/0.25mm which IMO is mighty thin for dial cord. Of course your opinion will be different.

Feel free to shop wherever, I’m just trying to make the point that any appropriate diameter fishing braid will do, the cheaper the better. Dacron, Deenma, Kevlar, whatever. The base material doesn’t matter.

[Audiorepair]

I didn't see anything for only $4 and as usual, Amazon is overpriced.  As I recall, the stuff to use is around 30 lb but my memory on that is hazy.  Stretching isn't usually a problem, since there are springs there anyway to keep the string taut.

The motorised faders don't 't have any springs, and presumably due to wear of all the various moving parts and the motor, are no longer working smoothly enough.
So it is critical to replace the cord with something at least as good as what is currently on it.
I also need to play with adjusting the tension, currently the cord is cut very short, and it is not possible to adjust it at all.


Edit:  I'm liking the idea of fishing line, I'm not a fisherman so hadn't really considered it properly.
Have ordered some 8 braid PE 0.5mm 90lb line so see how it fares. 
£7.50, Amazon.

Thanks to all.

[richnormand]

"The motorised faders don't 't have any springs, and presumably due to wear of all the various moving parts and the motor, are no longer working smoothly enough."
In that case you might consider putting a lever with an idler pressing against the string if you have space. Than way you either could have a sring providing tension or a hard tension adjustment. I would think that most strings would have some stretch initially and need adjustment later before stabilising.

[Wallace Gasiewicz]

I repaired some Collins equipment that used nylon covered wire for tuning cord. Wire covering was worn out after 50 yrs....
Replaced it with covered steel leader material from Bass Pro shop. (Pike leader) worked great.
You can use the crimp style tubes for terminating the wire.
Do not know if wire is acceptable in your situation.
It is a bit hard to tie knots in Kevlar. They usually have a recommended knot on the package.
Wally

[tanveerriaz]

i pick  a steel flexible Nylon Coated cable about 6 feet in junk. may be use in photocopy machine .

https://www.amazon.com/Stainless-Steel-Aircraft-Cable-T304/dp/B00THGV7W8

[Stray Electron]

      Dial cord made from cotton or fiber was pretty unique because it had so little stretch when it first came out in the 1920s but today there are a lot of different types cords made from synthetic materials that won't stretch. Nylon cable lacing cord for one.  Stunt kite line (kevlar) for another. Even nylon fishing line.

   FWIW many years ago tuner cord was also used in in U-Control model airplanes to control the elevator movement.  The first model plane that I had didn't use a bell crank and a push rod to operate the elevator. The external control lines connected to two built in control lines that routed through the wing and to two small brass tubes that made a 90 degree bend and the elevator had posts that stuck up and down off of it and the two control lines connected directly to the two posts.  The same airplane used an spark ignition system with a battery, points, ignition coil and a spark plug!

[andy3055]

This is the kind of stuff I used: https://www.ebay.com/i/303804094800?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=303804094800&targetid=1068323854750&device=c&mktype=pla&googleloc=9031993&poi=&campaignid=10897343926&mkgroupid=106040611134&rlsatarget=pla-1068323854750&abcId=9300403&merchantid=101648809&gclid=CjwKCAiAz4b_BRBbEiwA5XlVVjHcxokncUYLIG9ZXoR10oAntCyDKFSU1ySsdPYrkvvhRuJ-6H0LSBoCHasQAvD_BwE

It is somewhat like the cord used in window shades but much less in diameter.