Anybody have experience with single-carbon-arc welding on steel?
I gather it was the first arc welding process developed and very
quickly replaced, but would like to know if it has a place in
"hobby" welding, where quality of weld matters, as does cost,
but speed isn't so important. Seems to me it should resemble
O/A welding with a reducing flame. Stick welding never much
appealed to me, especially in small work, because the heat and
filler can't be controlled separately.
thanks for reading,
Are you talking about a carbon arc torch - two sticks of carbon and an
arc between the two? Used much like a oxy-acet torch for brazing, but
difficult to control the heat.
Or some sort of single carbon and strike an arc to the parent metal?
Heat control probably similar to stick welding and you need to add
As you say, "developed and very quickly replaced", there was a reason
Yes, that's it. Size the electrode and current to the base metal thickness
for a stable arc, add filler as needed. Rather like gas welding.
That's the clue I'm looking for. If it was replaced because it's slow
that's ok. If it was replaced because it's hard to control, especially
for thin (.062 material) the process won't be of much interest. If it
makes brittle welds that's another handicap, but a reducing O/A flame
isn't a problem if one works briskly with low carbon filler. (And
isn't building an airframe!).
Copper clad electrodes seem likely to cause weld contamination
but bare electodes appear to be available for fussy gouging jobs.
AWS handbooks would be informative but rather pricey outside a library.
I'll check the local libraries.
Thanks for reading,
In nearly every instance when things are replaced, superceded, by
another technique, it happens because the later techniques is better,
in some manner. Faster, stronger, easier, cheaper.
You seem to intimate that for some reason oxy-acetylene is not to be
used to build an airframe. Strange.
You see, I qualified with oxy-acetylene when it was the designated
method of building, or repairing, aircraft airframes and years later
welded a bloke's home built airframe which was later subjected to an
airworthiness inspection. certainly the CAA/FAA didn't seem to have
any objection to using oxy-acetylene :-)
The real question is, "why bother"? One can easily weld with
Oxy-Acetylene, Stick, TIG, MIG, or any of the submerged welding
techniques. Why would one want to bother with carbon electrodes?
Agreed. Cheaper is my keyword. Easier is next. Stronger is nice,
but this isn't a critical project. Faster does not matter.
O/A with a _neutral_ flame is understood to be acceptable. I did a bit
of auto body work with a reducing flame (it was easier to carry a puddle
on thin material) and had trouble with weld cracking. Apologies if my
meaning was unclear or interpretation mistaken.
Understood, but a carbon electrode seem likely to produce a carburizing
atmosphere. Perhaps not to the extent of acetylene, but still reducing.
Then again, it might be worse.
For my part, cost, and curiosity 8-)
Thanks for reading,
That is one of the things you learn when becoming a welder :-)
Somewhere I have notebooks filled with information about rods, flame,
fluxes, parent metals, etc. I've probably forgotten all of it but that
is what you had to know.
But why the need for a carbonizing arc? The usual aim is for a neutral
flame, if oxy-acetylene welding.
Well, curiosity is a good reason, but cheap is, perhaps a bit far out.
After all, you'll need some sort of a power supply to drive that
carbon arc; hopefully a variable supply if you want any control of the
arc, so you might as well start out with a commercial welding set :-)
I'd like nothing better than a commercial welder, but I can't
justify the cost for what is essentially a hobby. A nice Miller
just got away from me and I will keep looking. In the meantime,
an improvised scheme that works within limitations is an entertaining
project. I played with carbon arcs as a child but never thought to try
welding. Then I learned O/A well enough to do useful auto repairs and
stick well enough for heavy (1/4") material. That equipment is long out
of reach now. TIG is the obvious next step, but that's a serious investment.
A carbon arc might be a useful compromise between the power of stick
and the control of O/A, provided the chemistry cooperates, using an
improvised power supply. If I can carry a puddle that makes a not-too
brittle weld in .050" mild steel it would count as a success, so the
goals are fairly modest.
Thanks for reading,
Err... You talk about an improvised power supply that will hold an arc
using a carbon rod, but stick welding, which is holding an arc with a
metal rod, is a problem?
As an aside, you can weld considerably thinner metal than 1/4" with an
At low currents it seemed to be. I could carry a steady arc with the
output of an old automobile generator (gen, not alt) using heavy pencil
leads (graphite) as electrodes. The current was probably in the low
tens of amps. Metal electrodes stuck badly.
I'd expect an alternator to work considerably better (more voltage,
self-limiting current, which is what I have and plan to try.
For a good operator with modern equipment (and maybe even not-so-modern)
that's no doubt true, but at least for me thin electrodes and low current
always spelled trouble. Carbon was vastly easier to strike and maintain.
Current sufficient to keep a metal arc going always seemed to make for faster
work than I found comfortable. That is a fault of the operator, but I'm
stuck with him...8-)
In a way, it seems I'm looking for an electrical version of O/A: Heat
independent of filler rate, perhaps more power density, no tanks and
(above all!) minimum capital cost.
Thanks for reading!
Well, as for equipment, I used to do it with a simple transformer
welding machine :-) But you can easily buy 1.6 mm electrodes which can
be used to weld some fairly thin metal, and I knew a bloke that
claimed to have some 1 mm rods, although I never actually saw the
Which seems to be saying that your weld puddle will have no protective
atmosphere and be fully exposed to the air. I have this feeling that
your weld beads are going to be somewhat less than an ideal
This is really the core question that wants an answer.
My (possibly mistaken) hope is that the carbon evaporated from the
electrode will scavenge oxygen leaving an atmosphere of CO. If
this does not happen the whole scheme won't work, which is the
knowledge I'm seeking. It may have been the reason for the original
abandonment of the process, but nobody has said so yet.
An O/A flame is CO mixed with hydrogen, far as I can tell free
hydrogen makes more trouble than it fixes at least with ferrous
alloys. On that basis a hydrogen free "flame" ought to be better
Thanks for reading,
According to the "oxy_handbook" the oxy-acet flame produces CO2 and
Water, the hydrogen combines with oxygen. Of course if hydrogen
combines with iron it weakens it. On the other hand the treatment to
eliminate hydrogen embitterment is baking.
Those are the end products. Inside the flame it is said that
"The flame at the apex of the small central white cone has a
temperature of about 3000 (C). At that point the flame is almost
entirely carbon monoxide surrounded by a jacket of hydrogen. The
temperature of the apex of the flame is too high to allow the
hydrogen to combine with the oxygen."
That quote is taken of Mellor's Modern Inorganic Chemistry, copyright
1967 but first published in 1912. How it was figured out escapes me.
Perhaps spectroscopy. It does seem to suggest that hydrogen embrittlement
should be common to O/A welding. Far as I know it's not a big problem....
Thanks for reading,
You can calculate the relative percentages of combined and dissociated
H and O from the bond energy and the temperature.
See Figure 3.
Also you can look at practical experience that says OA welding works
fine, whether or not you understand why, and test samples of your own
practice welds to destruction with a hydraulic press or BFH.
jsw, BS in Chemistry
I don't think the carbon is consumed nearly fast enough to expect any
shielding - the arc is mostly a nitrogen-oxygen plasma (ie, it's air, at
9000 degrees or so.) Any CO/CO2 that _is_ formed will be going _up_ with
the force of considerable heating, preventing it from having much of a
shielding effect unless you do all your welds overhead. What's getting
sucked into the plume across your active weld zone is air.
Any knowledge I have of welding with carbons is is purely historical,
not experiential, though I have experience using a _good_ twin carbon
torch (with a trigger to adjust the spacing - no 30 second limit - be
sure to bring a shade 13 or so filter and full leathers, they throw some
MEAN light (UV and visible) - we learned to braze with them using flux
coated rods and extra flux.
I believe that the early "electric arc separate filler rod" process used
a flux-coated filler rod - the classic tale of someone welding things in
an emergency is coathanger and wet newspaper. So you could probably use
a normal (cellulosic, anyway) stick rod as filler rod and benefit from
its coating/flux. Might want to use a normal electrode holder to hang
onto it. I suppose you could also rig up shielding gas for carbon arc
welding, but then you're spending money you should probably just spend
on a used TIG rig.
Honestly, if you are on a low capital budget and want a process like gas
welding, gas welding is it. If you happened to be working in non-ferrous
metals there are nice tiny "water torches" that save on buying gas, but
of course those are burning hydrogen/oxygen electrically generated at
the torch base, so not good for steel. Jewelers use them.
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
If that's true then we have the answer I didn't want to hear 8-)
Did you observe oxidation of the base metal?
That might be worth a try, if I get that far.
That may be where I end up. The one thing I didn't like about O/A was
the large heat affected zone.
I'm looking for general repair, mostly ferrous. Aluminum would be fun,
but not really necessary. No refractories or noble metals. Usually small
but bigger than jewelry. Bike frame size would be close, but less critical.
Thanks for reading,
Your mention of bike frames brings another factor into the discussion.
The "fastening together"of the steel bike frame is primarily a matter
of "gluing" together some extremely thin steel tubes so the choice of
"welding gear" is primarily based on that factor. Aluminum frame bikes
of course require specialized aluminum welding gear and the titanium
bikes even more esoteric equipment. The selection of the welding
equipment is primarily based on what parent metals are going to be
My first welder was a beat-up Sears AC arc machine I bought from a
band roadie for $30. He had broken the electrode jack plate and
replaced it with sheet metal, which shorted the secondary. The
low-range windings were darkened but still functional, and the frozen
fan turned again after I disassembled it and flushed out the congealed
salad oil. The friction adjustment on the Amps control was useless and
not repairable because I didn't trust the strength of my epoxy repair
to its broken cam handle, so I tied the handle in place with para
And then it worked fine for years.
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