Why cann't i solder this wire?

A

Andrew Holley

Well-known member
I need to change the connections on a welding gun, bought the new connector, cut off the old and have tried for two days to solder the wires onto the new connecter. Can not get solder to stick to the wire?? I know I have the wire hot enough, the solder balls up but does the stick/coat the wire/ Bad solder?
If I can get this to work, I will have converted a miller aluma pro plus to an aluma pro (saving myself at least a grand, so it's important this works)
Any help appreciated, thanks
 
Couple questions Andrew.

Is the wire copper or aluminum?

Did you flux before trying to solder it?

Just because solder will ball up doesn't mean the substrate is hot enough to allow it to flow. If the wire is a small gauge/big wire it has tremendous heat sink properties and you need a lot of heat over a short period of time. A lot of heat over long time will melt your insulation back inches. Make sure your heat source is up to the challenge - a typical hardware store heat gun won't be.
 
Andrew,

What Pete said plus; Assuming it is copper wire, is the copper bright and shiny? If not there may be a black oxidation on the surface of each strand of wire. Solder will not stick to this oxidation. The rosin in rosin core solder or the solder paste flux is designed to clean this oxidation but it may not be enough. Trailer wiring is affected by this and difficult to repair (make new connections) because of it.

I have been told that hydrogen peroxide will clean the wire without damaging the wire. I don't have any personal experience using the hydrogen peroxide so I can not comment on it's effectiveness.

I have had good success cleaning stranded wires by carefully flatting and separating the strands, then stroking with sandpaper or a "stainless" wire brush. You may have to re-separate and rotate the stands to expose as much surface to the cleaning method as possible.

Once cleaned, you should be able to make a proper solder connection with enough heat. I've had real good luck using the small high temp micro torches which use ordinary butane gas like a Bic cigarette lighter uses. they are hot, quick and precise in flame control.
iroda-mj300-microjet-butane-torch1.jpg

 
Problem solved.
Went back to home depot and bought a different brand of solder, (with lead) and it's working now.
Thanks for the advice, now keep your fingers crossed. If I can get this push/pull gun working with my welder, new boat is going to get started after the new year. I will be building something along the lines of a devlin scaup only much larger and putting and inboard/outboard unit in it (You can't imgine the amount of time/ paperwork I have in this thing already and haven't even bought a piece of aluminum yet.
 
The latest environmentally friendly solder doesn't contain lead. It needs more heat and a different flux to work. It is about lead in drinking water. I still use 50/50 for a lot of work, get it from stained glass supplier.
 
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