Joining "thin" wires

[bulleidboy]

I have some lamps (both yard and street) which come with very fine wires attached. These wires need to be lengthened. I do not seem to be able to "tin" the wires and then join them. The iron is running at 400degrees - is this to hot? Should the wires be twisted together before applying the solder?
The iron is clean. It is all getting extremely frustrating - I don't recall having this problem before. BB

[Steve M]

Are they the very fine wires that have a lacquer as insulation?
Have you tried scraping them with he edge of a blade first?
I would add a twist to the joint prior to soldering as well.

[yelrow]

Hi, Barry, somebody cleverer than i, will no doubt answer you, but i had a similar problem, yesterday. We were being insulated, for 1 Euro, when the guys hot wire cutter broke. I tried various ways to solder the small wire, without success. Finally, i dug out a tiny reel of solder, that i had never opened, and it worked, first time. Spoke to a mate last night who said make up of solder, differs, and, that i needed this particular type for tiny wires. Unfortunately, reels label has long since come off, but no doubt, the clever guys know which one.

[bulleidboy]

Thanks Steve and John for the suggestions. The wires are not lacquered and I have removed an extra 1/8th of insulation to expose a bit more of the wire. I will try a twist - that will at least help keeping two wires together. The solder is what I've used since I started - 60/40 (not lead-free).
I'll dig out another tip for the iron and see whether that helps. The lamps have a narrow shaft which goes into the board - so a small hole - I cannot have a huge dollop of solder, together with shrink wrap, as I will not get them through the hole. I'll have another go. You know what it's like when something that should be extremely straightforward is not - Aaaaah!.

[Hound Dog]

I have joined quite a few thin led wires simply by twisting them together and then applying an appropriate sized Heatshrink - absolutely no need for a soldier iron and providing you make the Heatshrink long enough to adequately encapsulate the pvc coating, then this acts as the strain-relief and the joint can be considered reasonably robust.

Of course it depends on the application but for something that is not going to be routinely disturbed, this is more than adequate...... all my layout lights are wired in this fashion and no problems to date.

Hope this helps - Richard

[Walkingthedog]

When we joined telephone cable wires they were just twisted together. That is fine as long as you seal the joint so it is airtight, shrink wrap being ideal for this.

[yelrow]

looks like a job for my newly arrived kit from america. No solder, just heat gun.

[bulleidboy]

I will give this a try - many thanks.

[Tricky Dicky]

One issue you may be having is that due to the thinness of the insulation the heat travelling up the wire is causing some of the insulation to melt and leach down the exposed core. This is where a solder pot is useful which is just a heated container holding molten solder and the ends of wires to be tinned are simply dipped in.

As an alternative to this I would try a technique I do not normally recommend as in normal soldering it results in flux burning off, but try melting a blob of solder on the tip and quickly dip the wire in the blob rather then bringing the iron to the wire. Once your wires are tinned soldering together should work as normal. You mention using solder you have always used if this is some years then oxides will have built up on the solder, try cleaning it with fine emery or wet & dry. Old solder can be a PITA to solder with, I suspect the oxide build up can be too much for the flux to deal with.

Richard

[bulleidboy]

Many thanks for all the suggestions. I have found twisting the wires together and then covering with heat-shrink appears to work. Also following the comment about solder "going-off", have decided that mine - now five years old - probably needs to be replaced. Barry