Fixing a Distorted coiled Handset Cord.

[TelePlay]

I forgot to mention that I think the coiled cords were made by tightly winding a round cord around a metal rod.

The rod with the cord in place was electrically heated to a temperature that was just below the cords melting point, a temperature at which the cord touching the metal rod deformed  and when allowed to cool over time, the cord stayed coiled.

If you look at a coiled cord, the inside of the coil is totally flat (from the metal rod) and if you look between the coils, the side of coils is  flat near the inside of the coil, the side of the coil closest to the metal rod.

So, to create a coiled cord they heated the cord material from the inside to a point where the round cord "melted" and took on the shape of the hot, round rod - flat. The flat coil sides shows how much of the rounded cord was flattened.

They may not have heated the outside of the round cord and, in fact, heated the rod in a cold chamber to keep the outside of the soon to be coiled cord from deforming, to keep it round.

It would be fun to put a voltage across a metal rod having a resistance, say a NiChrom rod (I'd hate to see the price of 3 foot long 3/8" diameter nichrom rod), and using a Variac to heat such a rod with a distorted coiled cord wrapped around it to a specific temperature for a period of time to reform the distortion.

Then there's passing steam through a 3/8" pipe for a specific period of time to heat and thus reform a distorted coiled cord.

Might be other ways as well.

[TelePlay]

If anyone here wins this 1955 WE Mediterranean Blue on eBay,

https://www.ebay.com/itm/326027537038

I would be willing to recoil the handset cord, if not physically damaged, for free if the new owner pays for shipping both ways.

[artdecobuchwald]

Hello all and a happy new year to you.  I recently restored a Stromberg Carlson 1211.  I chose to keep the non-original, but period, handset cord.  It is coiled plastic.  I was not happy with how it looked after a clean-up, so searched and found this topic.  The first picture details the rather disheveled cord.  I read everyone's posts and decided I would wrap the cord on a 2 foot 3/8" diameter steel rod and put it in the oven at 200 degrees on the convection setting.  After 2-1/2 hours I took it out and put it in the near 0 Fahrenheit temps outside for about 5 hours.  After this I brought it inside to acclimate for another 5 hours. This process really made a difference in coil consistency and tightness.  You can see it hanging on the door.  I then proceeded to reverse the coils and take another picture of it hanging.  Not a huge difference, but significant.  Now it is back on the phone and I think it really makes a huge difference to the presentation.  Thanks to all whose experimentation went before my project.  It was really a flawless experience because of this forum!

[TelePlay]

Well done. Glad the forum could help.

Wall phones have to fight gravity, unfortunately, which defeats some of the restoration efforts. At least the coils are once again uniform.

I use an aluminum rod which seems to better transfer heat to the inside surface of the coils.

IIRC, phone manufacturers used to electrically heat the metal rod to create coils out of straight, round cord. Would take it up to near melting to form the coils. That's why the inside of the coils are flat and the inner sides of the coil show signs of the cord coils sticking together.

They must have used a metal rod with some resistance causing it to heat when a voltage was applied.

What you did is very good.

[artdecobuchwald]

Thanks, Teleplay.  Yes, aluminum is a great conductor of heat.  I would have used that had I not easily located the stainless rod.

Now the big question is, what phone to do next.  I always seem to have some contenders lying around vying for their chance...

Adam

[Jim Stettler]

IIRC, phone manufacturers used to electrically heat the metal rod to create coils out of straight, round cord. Would take it up to near melting to form the coils. That's why the inside of the coils are flat and the inner sides of the coil show signs of the cord coils sticking together.

They must have used a metal rod with some resistance causing it to heat when a voltage was applied.
WE used a 3/8" metal rod and baked them in an oven. Im pretty sure i have read the specifics in some old posts

What you did is very good.

WE used a 3/8" metal rod. and an oven .
electrically heating the rod was likely a later technique.
Ther are old posts regarding the techniques. likely searchable under recoiling cords is my best guess for topic.

[MaximRecoil]

The easiest and quickest method in my opinion is to submerge the cord in boiling water for a few minutes (I do it for 5 minutes). Boiling water ensures even heating of the cord to 212° F, and heating it for any longer than it takes for the cord to reach the target temperature doesn't do anything (nor does it hurt anything).

I use a 7/16" diameter steel rod (3/8" diameter is too small for the fatter cords like my two H4BR cords; 7/16" is perfect). I use the biggest pot I have (6 or 7 quarts I think) filled to the brim, and just put the rod in the boiling water at an angle and let it hang over the side. It's just barely big enough to work with a standard length cord; for a longer cord I'd have to come up with something else, or do half at a time.

I didn't think to take a "before" picture of the cord I just did, but it was messed up on the handset end because it had a reverse twist there for so long that it took a set, and undoing the reverse twist didn't make it look much better. It also had a bend in the middle. It's perfect now though:

[SUnset2]

The easiest method for me is to preheat the oven to 200 F, and then wrap the cord on a 3/8 inch wooden dowel, securing the ends with cable ties.  When the oven is well preheated, I turn off the oven and put the cord on the dowel on the rack.  I leave it in there until it is cool, and remove it before using the oven for something else.  This seems to work well enough for me.  I had to get a longer dowel for the longer cords used on wall phones.

[TelePlay]

I use a 7/16" diameter steel rod (3/8" diameter is too small for the fatter cords like my two H4BR cords; 7/16" is perfect).

Three rods are needed for recoiling cords.

1) 7/16" for very old cords
2) 3/8" is needed for most phone cords
3) 1/4" is needed for really new (post ~1985) cords

Metal rods are superior to wood, especially if using the boil water method.

[MaximRecoil]

1) 7/16" for very old cords

My two H4BR cords that need a 7/16" rod are from 1957 and 1958, though I'm not sure age is the determining factor for cable and coiled diameters, because most 500s and 554s I've seen on eBay that are as old or older appear to have a skinnier cord (the kind that would take a 3/8" rod). I'm just guessing though, because I'm just going by pictures rather than measurements and cords have often been replaced too.

I can't seem to find any detailed information anywhere about what handset cords (part numbers) were originally used and when.

[Contempra]

The easiest and quickest method in my opinion is to submerge the cord in boiling water for a few minutes (I do it for 5 minutes). Boiling water ensures even heating of the cord to 212° F, and heating it for any longer than it takes for the cord to reach the target temperature doesn't do anything (nor does it hurt anything).

I use a 7/16" diameter steel rod (3/8" diameter is too small for the fatter cords like my two H4BR cords; 7/16" is perfect). I use the biggest pot I have (6 or 7 quarts I think) filled to the brim, and just put the rod in the boiling water at an angle and let it hang over the side. It's just barely big enough to work with a standard length cord; for a longer cord I'd have to come up with something else, or do half at a time.

I didn't think to take a "before" picture of the cord I just did, but it was messed up on the handset end because it had a reverse twist there for so long that it took a set, and undoing the reverse twist didn't make it look much better. It also had a bend in the middle. It's perfect now though:

Just a silly question I've often asked myself: Do the two white wires in the handset cord serve the same purpose, or does one of them have a different function? I'm not sure if I'm making myself clear... but why are there two white wires?

[TelePlay]

Do the two white wires in the handset cord serve the same purpose, or does one of them have a different function?

The two white receiver wires attach to the GN and R terminals on the network which are shorted out by the dial mute leaves when dialing (the two white mute wires on the dial also connect to GN and R) to prevent the dialing "pops" from being heard when dialing. So they serve the same purpose as part of the muting circuit.

The handset red and black wires attach to the R and B terminals on the network.

Wiring diagram is from the TCI Library.

[MaximRecoil]

Just a silly question I've often asked myself: Do the two white wires in the handset cord serve the same purpose, or does one of them have a different function? I'm not sure if I'm making myself clear... but why are there two white wires?

They connect to the pair of screw terminals on the receiver element and are interchangeable with each other, i.e., it doesn't matter which of the two white wires connects to each screw terminal. I've wondered why that is myself, since the receiver element is a speaker, and speakers normally have their pair of terminals marked for polarity. I suppose it's because there's inherently only one speaker in a handset, whereas a normal speaker is often accompanied by one or more other identical speakers playing the same frequencies or at least the same frequency range, and if they aren't all wired for the same polarity, you can get frequency cancellation.

On the newer modular handsets, those two wires are different colors (white and green), yet the receiver element still isn't marked for polarity, and even if it were, there's no indication of polarity on the network (the GN and R terminals that TelePlay mentioned). I have no idea why they changed from two white wires to white and green.

As for the red and black wires that connect to the screw terminals on the transmitter cup, I don't know if polarity matters on those or not. I've never seen a Western Electric transmitter cup that was marked for polarity, but the red wire is usually connected to the terminal that contacts the center of the transmitter element. I have a non-WE transmitter cup (G3-type, from a third-party payphone handset) that is marked for polarity though. Its center terminal is marked positive (+), which is how WE handsets are usually wired when I get them (which includes several that were NOS when I got them), assuming the normal convention of red wire in a red & black pair = positive.