solderig enamelled wire, problems.

Put some methylated spirits or ethanol in a small open metal container such as the lid of a bottle . Set fire to it and hold the end of the wire in the flame until it is red hot. Plunge it downwards into the liquid and slide it out sideways so it doesn't get heated a second time.

There will be a chemical reaction between the oxide on the red hot copper and the ethanol, which removes the oxide and leaves the wire bright and clean.

Have a piece of metal ready to put over the container to extinguish the flame and plan in advance how you will deal with the rapidly-spreading fire if you upset the container. Put the bottle of ethanol some distance away.

Un bel giorno snipped-for-privacy@spenarnc.xsall.nl digitò:

For single wires I think that the scraping+soldering method is the quickest. First scrape the wire end with sandpaper, then immerse it in a bubble of fused solder until the remaining enamel washes off.

For Litz wires I still have to find a good method. The other day I had to manually solder a Litz wire into a wire lug. Very tedious. If you keep the wire immersed in a fused solder bubble, and keep adding new solder to add flux, eventually the coating gives up. But with this technique you waste a lot of solder, and you need a VERY good ventilation (those fumes are quite bad for you).

Probably there are specific solvents to do that, but I suppose it depends on the enamel type. Some say to use acetone, others sodium hydroxide, others sulfuric acid (which is an hardcore alternative to the aspirin :-)).

Fun. I’ll try it outdoors sometime, but not at my bench!

A less exciting approach is a bottle of GC Strip-X. I don’t know if it’s still available—I don’t recommend using that as a search term. :(

The right answer is probably a solder pot.

Cheers

Phil Hobbs

When I worke at Eddystone Radio, that was the standard method of dealing with Litz wire. The meths pot was like an old fashoined whale-oil lamp with a spout and it was mounted in an asbestos-lined steel box with a hinged lid that could be flipped down in emergency.

The chief engineer also used it to light his cigarettes.

I buy thermal-strip wire. You just solder it.

Make sure that the scavenged magnet wire is actually copper.

If the enamel is a dark colour, it may be a high temperature grade requiring manual scraping for removal.

In the past, you may have been working with 60/40 lead solder with rosin flux. Various other types of solder and flux are now more common, for lead-free environments. They may not flow and lift contaminating films as easily.

Red-hot temperatures should not be neccessary, nor an open flame.

RL

This doesn't appreciate the fact that better and better plastics are used. E.g. a bag of nuts can't be opened by hand, you really need a knife for that. The inner surface of a soda can is coated. I tried to burn it off, then polish it. Forget it! The soda can is destroyed before the coating gets it. Mechanical removing of the coating is always possible, but it is increasingly difficult if the wire gets thinner, 0.25 mm.

I'll try the Liz method. This resemble what I have already tried, but my wire melted. It is also clear that I have to have tinned the wire before winding the coil.

Some wires now have a 'self-fluxing' coating, which breaks down at soldering temperature and allows the wire to be easily tinned, but your description of the problems you were having suggested that this wire wasn't the self-fluxing type.

You may find that the lower temperature of an ethanol flame doesn't melt the wire (assuming the wire is copper, not aluminium). The base of the flame will be cooler than the top, so you may be able to find a suitable temperature zone which produces just enough heat to remove the oxide when you quench it. The wire should then be easily tinned with ordinary flux-cored solder.

I'll have to try this. The ethanol has to be acting as if it were producer gas or the like.

Is that GC, or MG Chemical? GC makes mechanical strippers these days.

Which won't work with Formvar coatings at all. There are stripped mechanically, with rotating rubber eraser wheels that wear plastic far faster than copper.

What would also work would be a small pot of hot lye solution.

I've used the melted aspirin tablet approach, and it does work, but the smoke is quite noxious.

GC, as in General Chemical, iirc. Famous for Q Dope among other radio stuff.

Cheers

Phil Hobbs

I think the active ingredient in the old style paint strippers was methylene chloride, hard to get these days, but you can still get solvent based epoxy paint strippers which have substituted a solvent not yet proven to be a strong carcinogen. Jasco Premium Paint & Epoxy Remover is one example readily available in the US.

Zylene is also readily available in the US, it will strip construction adhesive (epoxy strippers won't), haven't tried it on epoxy but it might work. Use in something resembling a fume hood, it smells like your olfactory nerves are being attacked by a blowtorch. Epoxy stripper is not much better.

The alcohol torch method is probably a lot safer, or mechanical stripping of solid wire (hard to do on litz).

Glen

If the wire is getting too hot too fast and melting, or if the wire cools down too much so that it is no longer red hot when it plunges into the alcohol, then it can help to twist it with a bunch of short similar diameter copper wires (which can be bare copper e.g. from a mains cable), so that the wire being heated has more thermal mass. If I can get the thermal time constant to be at least a second, I find that makes the process easier to control.

Really, I would buy some wire with solderable enamel. This will save time in the long run.

That's an excellent idea and it makes subsequent soldering much easier too.

I have seen something like that where very fine windings were brought out to terminals by thicker ones but had previously assumed it was just to prevent damage to the fine wire by leading it out through the layers of insulation. A lot of older devices: transformers, headphones, electromagnets etc. from the valve days, needed high-impedance windings and this technique was often used. I expect it made the assembly work a lot faster and less tricky - and the product more reliable.

Methylene chloride, right y’are.

Thanks

Phil Hobbs

The problem seems to be that "GC" is heavily overloaded.

.

I found the original MSDS. Google for "GC Strip-X 10-2602.pdf" (without quotes). It's Methylene Chloride, Phenol, and Ammonia.

That's correct.

Methylene Chloride was recently forbidden across the board, so there are no effective chemical strippers left. Other than boiling lye.

I don't think that Xylene will strip catalyzed films fast enough to matter. It takes small molecules that can diffuse into the film.

As has been suggested, wrapping the fine Litz wire strands around a heavier lead wire and using the alcohol torch and dip method on the whole assembly, immediately followed by soft soldering, sounds best.

Joe

are you sure it is copper and not copper coated aluminium?

Wouldn't the aluminum reveal itself by melting?

Joe

yes, copper usually just glows, aluminium melts

I find it unlikely with house hold items to find aluminum wires.

The wire I use is .25 mm. In a natural gas flame this melts readily. This must be copper or I would have not the slightest chance to solder it.

Groetjes Albert