carbon arc control

Here's a couple of issues to consider. First of all, a carbon arc wants about 30-40 volts across it for stable operation. Your voltage is way too low. Secondly, a carbon arc is usually produced between 2 carbons, not one and the work. The flame between the 2 carbons is used somewhat like a torch rather than a stick welder. The arc is better as an intense light source than as a welder/ cutter. There's a reason why carbon arcs aren't widely used to cut and weld and that's because there are much better ways to do it.

Be sure to protect your eyes and skin from the UV radiation. It can do lots of painful damage in a hurry.

Gouging rod

Gunner

No 220-pound thug can threaten the well-being or dignity of a 110-pound woman who has two pounds of iron to even things out. Is that evil? Is that wrong? People who object to weapons aren't abolishing violence, they're begging for the rule of brute force, when the biggest, strongest animals among men were always automatically "right". Guns end that, and social democracy is a hollow farce without an armed populace to make it work. - L. Neil Smith

Gunner wrote: [near total snip]

Here's a couple of issues to consider. First of all, a carbon arc wants about 30-40 volts across it for stable operation. Your voltage is way too low. Secondly, a carbon arc is usually produced between 2 carbons, not one and the work. The flame between the 2 carbons is used somewhat like a torch rather than a stick welder. The arc is better as an intense light source than as a welder/ cutter. There's a reason why carbon arcs aren't widely used to cut and weld and that's because there are much better ways to do it.

Be sure to protect your eyes and skin from the UV radiation. It can do lots of painful damage in a hurry.

Gunner

A carbon arc is usually used as a flame between two carbons, as Gunner says, to HEAT the job so that you can BRAZE it, not weld it!

The size and sound of the flame varies according to the gap you have between them, and how evenly matched they are to each other. If one is much shorter than the other, you'll get a very weird lop-sided flame, and it will tend for the arc to blow out easily. The sound can vary from a soft hissing to a loud buzzing, according to the gap and current setting. For thin sheet, you really need a low current setting, or the flame will blow right through the sheet, rather than just heating it! High currents will also burn the carbons very fast, but do less real work.

Carbon arc for brazing is much less equipment costly than oxy-acetylene, but is heavy on carbons, and you can't really heat very large areas. I find it useful for small jobs in thin sheet and tubing, but I have to watch out for the arc blowing the metal away! For bigger I use stick welding, and for smaller I use propane and silver solder. This is ALL amateur stuff, not pro! (I don't have oxy, mig or tig!)

Dave (uk)

p.s. arcs will burn your retina very rapidly if you look at them, so use a shield at all times.

twernt me. I simply mentioned Gouging Rod

Gunner

"Guns aren't toys. They're for family protection, hunting dangerous or delicious animals, and keeping the King of England out of your face."

-- Krusty the Clown, "The Simpsons"

Not like an acetylene flame ... because it was very hot? Hmm.

At a 3.1:11.8 (about 1:4) ratio, the transformer would produce about 30 volts out from 120 volts in, so Eric possibly could strike and maintain an arc between carbons (until a breaker goes or the transformer burns up). Even so, a carbon arc probably isn't useful for welding thin steel sheets together, but would work ok for brazing.

-jiw

...

Hi James. Thanks for the clarification. I did not measure the output of the transformer at 120 V in, since I don't like to measure things when they are running (being fed with a 12 V test transformer doesn't count). The output should be pretty near 30 volts, perhaps a bit less due to drops caused by the higher currents flowing through the leakage inductance.

The arc was sufficiently fierce that there would probably be no problem maintaining an arc between two carbons. The problem was in maintaining an arc between the resistance soldering carbon and the workpiece. It melted the metal away too fast. It was a good experiment, though, since I wanted to know that the hand wound transformer (it was a pain to wind, believe the people who post these warnings) actually worked, and it is getting difficult to find arc carbons. Didn't want to have a bad transformer and a couple of useless carbons that were hard to find. The local store has stopped selling them. And, it is now hard to find carbon zinc batteries. Most are alkaline, which don't have the central rod. I did find one on the bus one day. That's the one which the resistance soldering carbon was salvaged from.

Thanks for the tip about welding. I was not sure that carbon arcs were suitable for welding, but I wanted to make sure that they could melt brass rod.

Thanks, Eric

Hi Gunner. Thanks for the tip. I heard from various newsgroup posts that gouging rod is difficult to keep a stable arc with, but with carbon rods getting hard to find these days, they are worth a try.

Thanks, Eric

to HEAT the job so that you can BRAZE it, not weld it!

Hi Dave. Thanks for the reply. I will try out the two carbon type torch as soon as I can get some more carbons. I wanted to make sure things worked a bit before hunting/scavenging for carbon arc rods. They are getting hard to find.

between them, and how evenly matched they are to each other. If one is much shorter than the other, you'll get a very weird lop-sided flame, and it will tend for the arc to blow out easily. The sound can vary from a soft hissing to a loud buzzing, according to the gap and current setting. For thin sheet, you really need a low current setting, or the flame will blow right through the sheet, rather than just heating it! High currents will also burn the carbons very fast, but do less real work.

This is exactly what I was looking for. I guess I need a current control knob on my setup to make things work better. I didn't know that current control was so critical.

oxy-acetylene, but is heavy on carbons, and you can't really heat very large areas. I find it useful for small jobs in thin sheet and tubing, but I have to watch out for the arc blowing the metal away! For bigger I use stick welding, and for smaller I use propane and silver solder. This is ALL amateur stuff, not pro! (I don't have oxy, mig or tig!)

shield at all times.

Thanks again, Eric