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Fixing a Distorted coiled Handset Cord.

Started by Dan/Panther, October 17, 2008, 12:20:15 AM

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cloyd

Thanks, that helps!
Did you drill holes through each end of your dowel for the wire to suspend it and the cord?  I'm guessing you don't want the cord to rest on the 2" PVC tube when it is getting so hot.
I'm going to put this on my list of things to make!
Well done!

Tina Loyd
-- I am always doing what I cannot do yet, in order to learn how to do it. - Van Gogh -- 1885

TelePlay

Quote from: cloyd on September 04, 2017, 04:56:05 PM
Did you drill holes through each end of your dowel for the wire to suspend it and the cord?  I'm guessing you don't want the cord to rest on the 2" PVC tube when it is getting so hot.

No, I run the station wire through the holes in the end of the 2" pipe and around the dowel. Do that from 3 different angles and I have a way then to adjust the dowel, to get it centered. That's a temporary thing. Now that I know the oven works, to both hold and center the dowel I had planned on drilling and tapping 3 holes, 120° apart in the 2" PVC and then using thumb screws, like in a Christmas tree stand, to center and hold the rod. I'd epoxy glue a nut and washer on the end of each thumbscrew to provide a larger surface to engage the dowel.  Plans in the works, no time to do that yet. Next time I need to tighten a cord, I will get to that.

I have since purchased some smooth, round aluminum rod 4' long by 3/8" diameter. Wood is an insulator. Aluminum will allow the handset cord to heat all the way through. Haven't had time to try that yet.


TelePlay

It's been some time since I found 3/8" round aluminum rod in a 3' length but I finally got a change to use it today.

Did everything the same as I did with wood dowel and it turned out well. Once again I forgot to take a before photo but I do have the first image from the eBay listing. The handset cord really is matching beige, just dirty grey. You can see it was not in the worst shape but it was stretched out in the usual places.

After cleaning, wrapping on the aluminum rod, heating, cooling and unwrapping the cord, it turned out nice.

One thing I did notice was the cord stuck to the aluminum meaning the whole cord was heated. One thing I learned is before doing this, reverse twist the cord so it is back in the original position it was when made and then reverse twisted by WE. I get a better coil when doing it that way, reproducing the way it was done by we when they made these from round cords.

By the way, the phone had 4 sticker areas, glue only, and the one in the box was removed with a wood chisel - left gouges in the plastic which took a half hour to sand out.

It's a bit dis-colored, some of which came out in bleach, but leaving it as it for I know where it is going and how thrilled the guy will be to get it for free. A favor for a favor, not a collector's level phone.

TelePlay

Quote from: cloyd on September 04, 2017, 04:56:05 PM
Thanks, that helps!
Did you drill holes through each end of your dowel for the wire to suspend it and the cord?  I'm guessing you don't want the cord to rest on the 2" PVC tube when it is getting so hot.
I'm going to put this on my list of things to make!
Well done!

Tina Loyd

     Regular Member Post

To complete this project for those who are interested in physical phone restoration work, I installed my idea of how to hold the cord carrying rod in the center of the inner tube.

After drilling 3 holes 120° apart in each end of the inner PVC tube, I tapped the holes and screwed 1/4" NC 20 machine bolts into the inner PVC tube. They meet in the middle and hold the rod, a 3/8" aluminum round, in the center keeping the coiled cord on the rod from touching any part of the inner tube during heating and allowing an even hot air flow around the coiled cord. The bolts are easily turned into and out of the PCV threaded pipe by hand and quickly place the rod in a centered position.

The aluminum rod replaced the wood dowel originally used because wood is an insulator and keeps the inside of the coil cooler and not heat treated as much as the outside of the coil. The aluminum rod attains the same temperature as the cord and as such, heats the inside of the coil to the same temperature as the outside of the coiled cord. This provides a much better reforming of the coil than when a wood dowel was used.

This set up has always worked well for me to turn a cleaned, stretched out handset cord into a tight, like new coiled cord.



19and41

The last 3 or 4 coil cords I've had to clean and put a permanent in,  I have used a plastic coat hanger with the section cut out at the base of the hook to the end of the horizontal section.  I can thread the coil onto it, twist tie one end below the hook and snug it up and twist tie the other end at the cut end of the horizontal.  I give the cord a good saturating spray of scrubbing bubbles bathroom cleaner and rinse with hot water.  I give a wipe off, then run the hair dryer over it and let it set awhile to finish drying.  It just hangs up like a normal hanger.
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke

TelePlay

Quote from: TelePlay on April 22, 2018, 08:51:13 AM
The aluminum rod replaced the wood dowel originally used because wood is an insulator and keeps the inside of the coil cooler and not heat treated as much as the outside of the coil. The aluminum rod attains the same temperature as the cord and as such, heats the inside of the coil to the same temperature as the outside of the coiled cord. This provides a much better reforming of the coil than when a wood dowel was used. This set up has always worked well for me to turn a cleaned, stretched out handset cord into a tight, like new coiled cord.

     Regular Member Post

My tube furnace continues to turn out fantastic results, even better since I started to use an aluminum rod.

I usually forget to take before images but did so this morning. The cord wasn't "that" bad but it needed recoiling.

After 45 minutes in the furnace with the hair dryer on high (and letting it cool naturally over time - about and hour), the cord coil was restored. The aluminum rod lets the inside of the coil in contact with the aluminum rod and attain the same temperature as the outside of the coil when on the rod, something wood could not do since wood is an insulator. The cord is fully heated with the metal rod.

(Note: the color difference is due to the background used; the before was taken on a grey cloth and the after on a white board - shows the iPhone camera has a problem, or is given a problem, by using certain colored backgrounds, the dark red is more accurate).

FABphones

A collector of  'Monochrome Phones with Sepia Tones'   ...and a Duck!
***********
Vintage Phones - 10% man made, 90% Tribble
*************

TelePlay

#97
Here is another restored cord. After cleaning the cord and getting the coils all going in the same direction, the cord showed a bend near the middle which did not look good when handing from the handset. 45 minutes in the furnace and it's near NOS.

HarrySmith

Nice! They do come out looking like new! Great job! Thanks for sharing with us. I seem to be working on all cloth cords right now so I have not needed this yet but I am excited to try it out. Have you had one done long enough to tell if it is a permanent repair or not?
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

TelePlay

Quote from: HarrySmith on July 12, 2018, 12:28:16 PM
Have you had one done long enough to tell if it is a permanent repair or not?

The beige 554 (above) was done 3 months ago and is still in the same condition.



With normal use, they don't return to the "before" state. Any coiled cord can be wrecked by overstretching, I suppose.

I clean the cord with a mixture of 10% Acetone, 10% MEK and 80% Denatured Alcohol (really take off any hard fast grim better than soapy water, soapy water left crud this mixture then removed quickly so I start with the mixture) and after I put the cord on the aluminum rod, I go over the outside of the rod mounted cord with that same mixture. It tends to make the rubber cord a bit soft and going over the coils with a wet cloth of the mixture, some of it gets between the coils and along the rod. This, of course, evaporates off but seems to leave a better coil restoration. Can't prove anything since I would need two identical cords and treat one with the mixture to see the difference.

After 45 minutes with the drying on high, the aluminum rod on the ends outside of the furnace are too hot to touch so the inner coil has to be equally affected by the heat. Just my observations from doing them.

The next time I post a before and after cord will be of a badly distorted cord. Did one once successfully but, as typical many times, no pictures.

FABphones

That beige 554 looks like it has just been taken out of the box.  :)
A collector of  'Monochrome Phones with Sepia Tones'   ...and a Duck!
***********
Vintage Phones - 10% man made, 90% Tribble
*************

TelePlay

If anyone is still trying to restore distorted coiled cords, heat is still the answer. A 3/8" aluminum rod is used to distribute the heat applied to the inner side of the coil. The metal acts as a heat sink and becoming hot itself, slows the cooling process to insure annealing of the heat treatment.

Using a new dry heat source that takes about 3 minutes to heat the cord evenly to a temperature above 190° F but not over 200° F (anything over 200° F runs the risk of melting the cord). I use a digital hand held infrared thermometer to check the cord temperature during heating.

The process steps are to first wash and dry the cord, coil the cord tightly on the rod, heat the cord  to the above stated temperature range and allow it to cool slowly, for at least 30 minutes (I actually let it sit for hours before taking it off the aluminum rod).

Can do a cord from washing to treating in less than 15 minutes - washing takes the longest time.

MaximRecoil

#102
If doing it in an oven the way the article describes (268°F for 8 minutes), to get around the problem of the inaccuracy and hot spots of typical home ovens, you can put something heavy and dark-colored (so as to get an accurate reading off it with an infrared temperature gun), such as a large, well-seasoned cast iron skillet, in the oven and preheat it to say, 400°F. Then turn the oven completely off, leave the door closed, and wait a little while. Open the door briefly to check the temperature of the cast iron skillet periodically. When it gets down to 268°F, or whatever temperature you want to use, put the cord in for 8 minutes (still leaving the oven turned off).

The cast iron skillet helps retain heat in the oven (over a period of only 8 minutes the oven will probably only drop a couple/few degrees in temperature) and serves as a good temperature reference point (temperature guns are most accurate on dark surfaces, though if you have a good oven thermometer you wouldn't need the temperature gun). Preheating the oven initially to a much higher temperature than you need ensures that by the time it cools to the temperature you want, everything in the oven is at the same temperature.

If you have something even heavier than a cast iron skillet it would work to retain heat over that 8-minute period even better. For example, I have an 18" diameter, 3/8" thick mild steel plate, seasoned, that I use as a "pizza steel." It has a lot of thermal mass (it weighs 27 pounds), which is what makes it work so well for cooking pizzas. A 12" cast iron skillet usually weighs around 8 pounds. Bricks would work good too.

Contempra

Old post but useful .. I use  stick of wood with the hair-dryer without problem , of course I wash the cord before :) .

TelePlay

Quote from: Contempra on April 28, 2023, 08:37:40 AM. . . I use  stick of wood with the hair-dryer without problem . . .

Both work but have limitations.

A wood dowel is an insulator, will not heat up and conduct heat. As such, the inside of the coils, those in touch with the wood, will remain cool while heating the outside of the coils. There is no way the inside of the coils will reach the re-forming temperature with over heat (and most likely melt) the outside of the coils. A metal rod will allow raising the temperature of both the inside and outside of the cord coils uniformly. Heating only the exterior works but the unrestored curl in the interior of the cord will fight against the exterior restored coil, won't be as tight and/or the restored coil won't last as long.

Hair dryers work but are relatively low temperature compared with the commercial shrink wrap heat guns out there. One one hand it takes a long time to heat the cord with a hair dryer but the risk of damage is low. A commercial heat gun raises the temperature of the coil faster and higher but the risk of damage is high if not heating the cord uniformly and evenly.

The commercial heat gun does a better job quicker (especially if using a metal rod) but must be done thoughtfully.

I have created a heating jig to heat coiled cords on a metal rod using a commercial heat gun. Once the cord is cleaned and mounted on the metal rod, it takes about 5 minutes to reform the cord coil, plus cooling time. When done correctly, the inner coil will be slightly stuck to the metal rod indicating the interior of the coil had reached the desired reformation temperature (the cord is easily removed from the coil metal rod).

If using a metal rod, it takes at least a half hour for the coil on the rod to coil, I look at the process as being similar to annealing heated glass.