# Another theoretical question



## Bi11Hudson (Jan 4, 2021)

Perhaps it should be a hypothetical question about theory. Call it what you will, I've a curious idea and look to the combined resources of the group for possibile answers. The background of the theory is a TIG welder and a Plasma Torch. I have acquired a Plasma Torch for "future" use. I've never plugged it in, never even removed it from the shipping box. I opened it to look for shipping damage, but without material or projects, it isn't currently needed.

I do know how to "stick" weld, the old timer that taught me could write his name on sheet metal building siding without blowing a hole. I'm not that good, but do know how to stick two pieces of metal together well enough to climb on. A few years back, I rebuilt a John Deere 54 inch mower deck, welding on a new top plate. The bearing housings were home made and I had a real welder at the mill to weld the pieces together. Too cheap to buy real JD bearings. . .  My welder is a Lincoln AC-225 "farm" welder that has been converted to DC with a full wave bridge.

The Plasma Torch is essentially a carbon electrode, like a gouge rod of sorts.  The idea is to draw an arc and when the metal is hot enough, a stream of gas blows the molten metal out. The gas is optimally Argon, perhaps Nitrogen or CO2. The low end torch I acquired can even use compressed air. A dryer and regulator are onboard the welder, in addition to the usual paraphanlia on the combressor itself.

I know how to use an OA torch, having done so many times over the years. My Oxy tank is out of date by many years and I'm too cheap to refill it until I really _need_ it. Which isn't likely at this point. The burning torch is the smallest that Victor offers, as are the welding tips. The Plasma Torch was cheaper than getting my O2 tank hydro tested. And I'm about out of Acet, also out of date.

The TIG welder, to my understanding, has a carbon electrode to draw the arc, surrounded by an inert gas. The intensity of the arc is of lower intensity to avoid punching a hole in the work. A filler rod is fed into the "puddle" from outside. I have seen TIG results, but never the process of actually welding. Or seen the tip. . .

The *idea /theory /question /thought* is that a Plasma Torch has the essential structure for TIG welding. With a flow regulator on an inert gas to keep the flow very low, and the arc current down very low to melt without "melting through", what else is necessary to TIG weld? Keep in mind, I do not do welding commercially and work with _relatively_ small parts. I have a "small" tractor, 30 HP. And a 1 ton dump truck. Any welding on those would be done with a stick welder. The bearing housings on the JD mower deck would have been TIG welded had I the knowledge and equipment at the time. Those would be about the largest work I would want to TIG.

Any insights /thoughts /ideas will be most welcome. I will be off line for a couple of days, so answers well thought through will be optimal.

Bill Hudson​


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## Liljoebrshooter (Jan 4, 2021)

TIG has a tungsten electrode. 

Joe


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## Liljoebrshooter (Jan 4, 2021)

Here is a picture. 

Joe


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## benmychree (Jan 4, 2021)

TIG welding uses a tungsten electrode, not carbon; the only plasma torch that I have seen uses two carbon electrodes to produce a flame like arc, used much like an acetylene torch, I think these are not much used any more, if at all.  The plasma torch that you refer to Is the plasma cutting torch, it uses an internal tungsten electrode to project a high temperature flame, blown out the copper nozzle with either an inert gas, or plain shop air (much cheaper to use than inert gases).  The outfit for gouging uses a carbon electrode and blows a stream of air alongside the electrode to blow the molten metal out of the path of the electrode and is used for removing weld beads and preparing heavy sections for welding (weld prep).


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## benmychree (Jan 4, 2021)

The little grey cells finally kicked in; there are other plasma devices besides cutting torches, such as for welding and spray buildup; as with so many other mysterious processes, a little internet search brings more clarity, among other hits, this one gives a better overview of the subject.








						Plasma torch - Wikipedia
					






					en.wikipedia.org


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## erikmannie (Jan 5, 2021)

I have TIG welded a fair amount, and I would not want to risk getting into a situation where I had anything less than ideal shielding gas coverage.

I think we can assume that TIG torches have been engineered for optimal shielding gas coverage (either with a standard cup or a gas lens).

If you are talking about plasma arc welding (PAW), that is very much like TIG except the root of the weld is MUCH deeper. Plasma arc welding systems are VERY expensive. Do you have one of these systems?!

Along those lines, this article briefly discusses welding with a plasma torch:









						Plasma arc welding - Wikipedia
					






					en.m.wikipedia.org
				




Screenshot:


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## ericc (Jan 5, 2021)

Doesn't sound like a plasma torch.  It sounds like you have a carbon arc gouging torch.  Pictures would help.


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## erikmannie (Jan 5, 2021)

ericc said:


> Doesn't sound like a plasma torch.  It sounds like you have a carbon arc gouging torch.  Pictures would help.



I would be interested in having a carbon arc gouging torch if I had the money & space in my shop. I don’t have money or space or compressed air.


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## aliva (Jan 5, 2021)

Carbon gouging was also called Arc-Air. As said above the electrode is a carbon rod clad with thin copper, rod diameter was about 1/4inch When the arc is established the high pressure air is turned on and the molten metal is blown away. Uses a lot of compressed air and at least 200 +amps DC.
Very messy and loud


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## Bi11Hudson (Jan 6, 2021)

There may well be a mis-use of terminology in my question. My background is electrician, not millwright. First off, my experience helping with the arc gouge was in a foundry some 40 plus years back ('70s). We cast ductile iron, but for burning, a torch wouldn't touch the stuff. Same as cast iron, there. The "gouge" rods used by the millwright were a copper clad hollow carbon about 3/8 diameter. Air was passed down the middle and as the arc was struck, would blow out the arc bead. I have a few of the rods and have used them for lighting and a "flower pot" furnace. It didn't work that well but did melt metal.

The "plasma" torch I have is a cheap, $150 Chinese rig. The only time I've even seen it used was on YouTube videos. I haven't used it yet. The only stock I have is a roll of 18Ga roofing before rolling. Much easier to cut with shears. When things warm up next spring, I may try cutting some scraps. Mostly, it's a "toy" that might be handy someday, just in case. The concept of a TIG welder would be the same, a toy. Again, might be handy someday. But no plans to use it, no need for it as things stand right now.

In the videos I saw, the "torch" was grounded to the work. I couldn't see any useful details, but it looked like an arc welder functioning. Hence my thoughts about TIG welding. If a TIG rig uses two electrodes to arc between, then the thought is basically null. If it only has one and a ground, some thought might yield usable results.

.


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## General Zod (Jan 6, 2021)

a picture of your torch is worth a million words


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## Bi11Hudson (Jan 7, 2021)

General Zod said:


> a picture of your torch is worth a million words


I would have to dig it out and unbox it to take photos. And still couldn't convey the technical details even then.  The link is to eBay for the same machine, albeit a bit later. (The price is higher. . . ) You may well find details I don't even know to look for.









						110V/220V CUT50 50AMP Plasma Welding Cutter Digital Cutting Inverter Machine USA  | eBay
					

50AMP CUT50 Plasma Cutter Welding Cutting Machine Digital Inverter 110/220V. Model Number: CUT50. This cutting machine has these characteristics: stabilizing, reliability, lightness, save-energy, no noise, high cutting speed, cutting smoothly and no polish demands.



					www.ebay.com
				




The expression I remember was for a thousand words. The link may cover that. But a mil, not likely.
.


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## General Zod (Jan 7, 2021)

I see.  So based on that info, what you have is a basic plasma cutter.  Simply disregard the word "welding" in that Ebay description.  Make no mistake about it, that is a plasma cutting torch, not a welding torch by any stretch of the imagination.  To attempt to use that for welding would be futile, since the hafnium inserts in the electrodes are not meant to carry as much current as a true TIG welding machine, nor would you be able to manipulate the arc in the intended fashion as it is needed for TIG.  Oh and I use my own expressions.


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## Bi11Hudson (Jan 7, 2021)

Thank you, Sir, for a technical reason "it" wouldn't work. I don't know anything about TIG welding and was just dreaming about a "what if" thought. I really wasn't pursueing the "welder" portion of the eBay ad. I have dealt with the Chinese in the past and realize the difference between "associated with" and "used for" in the translation part.


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## Mini Cooper S (Jan 7, 2021)

As I understand it, the plasma torch that my son and I bought has nothing but a copper tip with a hole through it. An onboard compressor sends air through the hole carrying an electric arc to the work piece whick has the ground wire clamped to it.  The arc super heats the air stream turning it to the 4th. state of matter, "plasma", this burns through the work piece and blows the molten material away.  No gas cylinder or "rods" involved.  Works good on sheet metal which is what we bought it for.

Richard


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## General Zod (Jan 7, 2021)

Mini Cooper S said:


> As I understand it, the plasma torch that my son and I bought has nothing but a copper tip with a hole through it. An onboard compressor sends air through the hole carrying an electric arc to the work piece whick has the ground wire clamped to it.  The arc super heats the air stream turning it to the 4th. state of matter, "plasma", this burns through the work piece and blows the molten material away.  No gas cylinder or "rods" involved.  Works good on sheet metal which is what we bought it for.
> 
> Richard


Yup, that's pretty much the basic operation of typical modern plasma cutter.


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