solo - 15-5-2006 at 17:50
Ever need to solder some heavy cables but the soldering iron seems to not be up for the job or it takes forvever?........today in trying to repair my
starter I needed to solder a heavy wire going to the brushes and wouldn't you know it my soldering iron just couldn't get hot enough....I took my
starter to a electrical repair shop and the guy got a carbon rod, one similar like the one's you find inside of flashlight batteries, and he grounded
the starter with one lead from a battery and the other on to the carbon rod....then by touching the area needed to be soldered the carbon just glowed
and got the copper wire very hot that the lead solder just melted into the part needing soldering....never seen that before , I thought I share it
.........maybe it's old news, but hey, new to me.........solo
enhzflep - 15-5-2006 at 18:20
Seen a similar technique used to secure parts that are adverse to the application of heat.
I've seen the ends of small diameter wire - ~1mm melted into a ball, right ontop of
amythest and even plastic - without changing the colour or melting the plastic.
Very impressive, yet so simple. Can't think of a parallel aplication, yet like solo, thought the info could be of some interest.
Great way to apply high heat to a very localised area. For super-fine applications the
carbon rod may be sharpened in a pencil sharpener first. Sure beats an oxy-propane or
oxy-acetylene torch with a ruby-lined #1 or #2 tip...
12AX7 - 15-5-2006 at 18:55
That's like a big (and possibly redneck, depending on how professional it looked 
) version of the battery powered cold soldering iron thing they advertise on TV.
Tim
Mr. Wizard - 16-5-2006 at 11:06
The carbon rod soldering trick is as old as dirt, but that doesn't mean it isn't effective The rod from a battery is clamped into a copper tube that has a slot cut into the side, and a small clamp is put around the copper to make
a lower resistance connection to a braided wire run through the tube. The other end of the tube is mounted in a wooden handle, drilled to allow the
copper pipe and wire to go through it. Use the heaviest braided wire you can, otherwise the heat is developed in the wire, rather than in the carbon
to metal contact. The carbon is filed to a pyramid point. A heavy connecting clamp on the end of the wire is needed to connect to the automotive
battery. BTW this works with 6 volt systems as well, and is not polarity dependent. It's very important to use a good flux when soldering heavy
cables, as it is hard to see where the solder is not sticking. It's better to use the acid type plumbing flux for this type of work rather than the
rosin core electronics flux. I always solder all my battery cable connections, especially where corrosion is a problem.
unionised - 16-5-2006 at 11:23
"It's better to use the acid type plumbing flux"
"especially where corrosion is a problem".
It will be if you don't remove the acid flux residues.
Mr. Wizard - 17-5-2006 at 08:38
Use the acid type plumbing flux (LaCo works well) when you are trying to solder big corroded battery cables. If you have ever tried to solder a
corroded battery cable you know what I meant to say. Obviously cleaning the mess off the work after soldering is a good idea. I have had good luck
using the orange oil type waterless hand cleaner, applied with an old tooth brush, then followed by a hot water scrub.
I have found an acetylene plumbers torch works best on large copper wire and pipes. MAPP tanks work well too and are much cheaper.