Soldering fail. Ok... what am I doing wrong?

[Hiredgoon]

Oh how I hate crimp connectors.

18AWG is not particularly robust wire, you should have no problem heating it enough for this to work with pretty much any cheap-o soldering iron.

It's possible that the wires are contaminated, but dipping them in flux won't have much more effect than the 60/40 you're using, which already has a rosin flux core.

I tend to only use flux when soldering copper pipe, as it really is useful when soldering with a torch. In my experience a torch--even the little creme-brulee making ones--are a little too hard to control and I just wind up melting the insulation and burning my fingers.

I use a solid-core silver solder myself for all the electrics that I am working with, and I've noticed that it adheres a little better. I find the flux core is prone to sort of envelop the little bead of solder and make it want to slide off of my work; that could be what's happening.

As well, as you're new to this, don't forget to slip the shrink wrap sleeve over one of the ends of wire BEFORE you do your soldering, or you'll be doing it all over again. It's the most common mistake I see when I'm teaching new students.

[Grif]

Oh how I hate crimp connectors.

18AWG is not particularly robust wire, you should have no problem heating it enough for this to work with pretty much any cheap-o soldering iron.

It's possible that the wires are contaminated, but dipping them in flux won't have much more effect than the 60/40 you're using, which already has a rosin flux core.

I tend to only use flux when soldering copper pipe, as it really is useful when soldering with a torch. In my experience a torch--even the little creme-brulee making ones--are a little too hard to control and I just wind up melting the insulation and burning my fingers.

I use a solid-core silver solder myself for all the electrics that I am working with, and I've noticed that it adheres a little better. I find the flux core is prone to sort of envelop the little bead of solder and make it want to slide off of my work; that could be what's happening.

As well, as you're new to this, don't forget to slip the shrink wrap sleeve over one of the ends of wire BEFORE you do your soldering, or you'll be doing it all over again. It's the most common mistake I see when I'm teaching new students.

Agreed on all points.

I've been lucky enough to inherit some old school lead solder from my father (RIP). That stuff works the treat.

[SlowPro48]

A 25 watt iron is PLENTY big for joining 18 ga wire. If you've got a new iron, you need to tin the tip before you can effectively solder with it. Let the iron get really hot, wipe the tip off with a moist cellulose sponge then coat the tip with solder and wipe the excess off with the sponge. It should have a thin layer of solder all over it and is now ready for use. The tips on the cheaper irons are sometimes hard to tin for some reason. It sometimes helps to rough them up with some emery cloth first but I've run across cheap chinese tips that will not tin completely no matter how much flux and solder you throw at them. And 60/40 rosin core is perfect for your purpose.

One thing I've found that speeds up the soldering process is to let the iron get good and hot then just touch it briefly with the solder to put a small drop of molten solder on the tip. Then place the wires in this drop, using it to transfer the heat. If you just place a dry tip on the wire there's not much surface area contacting the wire thus not much heat transfer. The goal is to transfer as much heat as quickly as possible. Quick heat transfer aids in localized heating so you don't end up holding the iron on the wire for 30 seconds heating six inches of wire and messing up your insulation (and causing your shrink wrap to shrink too soon!) . Using this method (very hot iron and drop of solder to transfer heat) it should only take a couple seconds to heat the joint enough to touch the solder to the wire and it will instantly flow. Hope this helps.

[tom4bren]

One last point - What is the quality of the wire?

Good copper wire is easy to solder. Cheap wire can have a lot of other metals (especially aluminum) that can really dork up your soldering efforts. I recently tried to solder some cheapo jumper cable wires together & actually burned the wire before the solder could adhere.

I don't agree that a butane torch is hard to control when soldering. Unless I'm working in a really tight area, I actually prefer to use one. When in tight areas though, I have a nice butane soldering iron that works really well.

If the wire you are using is a good quality copper, then the solder and flux you can get from the plumbing department at Lowes/Home Depot works quite well. I've always had better luck with flux paste rather than relying on the 'stuff' they have in the core of the solder.

[RickOKC]

A 25 watt iron is PLENTY big for joining 18 ga wire. If you've got a new iron, you need to tin the tip before you can effectively solder with it. Let the iron get really hot, wipe the tip off with a moist cellulose sponge then coat the tip with solder and wipe the excess off with the sponge. It should have a thin layer of solder all over it and is now ready for use. The tips on the cheaper irons are sometimes hard to tin for some reason. It sometimes helps to rough them up with some emery cloth first but I've run across cheap chinese tips that will not tin completely no matter how much flux and solder you throw at them. And 60/40 rosin core is perfect for your purpose.

One thing I've found that speeds up the soldering process is to let the iron get good and hot then just touch it briefly with the solder to put a small drop of molten solder on the tip. Then place the wires in this drop, using it to transfer the heat. If you just place a dry tip on the wire there's not much surface area contacting the wire thus not much heat transfer. The goal is to transfer as much heat as quickly as possible. Quick heat transfer aids in localized heating so you don't end up holding the iron on the wire for 30 seconds heating six inches of wire and messing up your insulation (and causing your shrink wrap to shrink too soon!) . Using this method (very hot iron and drop of solder to transfer heat) it should only take a couple seconds to heat the joint enough to touch the solder to the wire and it will instantly flow. Hope this helps.

Woo hoo! I think that did it!

I tinned the tip - most bled off so maybe that's due to being a cheap iron. Then I melted a drop of solder directly to the tip and put it on the underside of my wires. After that, while keeping the iron on the underside of the wires, touching the solder on top FINALLY allowed it to bleed down through the strands.

Thank you - after several more practice runs, I think I'll feel confident enough to tackle my real project upside down under the VX. I see what you're saying about the shrink wrap, too - wow is that ever sensitive and shrinky!